WTNT43 KNHC 281442
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT THU AUG 28 2008

SATELLITE IMAGERY INDICATES THAT THE CLOUD PATTERN ASSOCIATED WITH
THE CYCLONE HAS IMPROVED DURING THE LAST 6 HOURS AND LATEST DVORAK
INTENSITY ESTIMATES INDICATE WINDS ARE NOW NEAR 35 KT. BASED ON
THIS INFORMATION...THE DEPRESSION IS UPGRADED TO TROPICAL STORM
HANNA. VISIBLE IMAGERY SHOWS THAT HANNA'S LOW LEVEL CIRCULATION IS
PARTIALLY EXPOSED ON THE WESTERN EDGE OF THE DEEP CONVECTION
INDICATING WESTERLY SHEAR...ASSOCIATED WITH AN UPPER-LEVEL LOW TO
THE WEST IS IMPACTING THE SYSTEM. SINCE THE OCEAN IS PLENTY
WARM...THE INTENSITY FORECAST IS PRIMARILY A FUNCTION OF HOW HANNA
INTERACTS WITH THE UPPER-LEVEL LOW. GLOBAL MODELS FORECAST THE
UPPER-LEVEL LOW TO MOVE WEST-SOUTHWEST OVER THE NEXT SEVERAL DAYS
PLACING HANNA IN A LOW VERTICAL SHEAR ENVIRONMENT WITH AMPLE
DIVERGENT FLOW ALOFT. SUCH AN ENVIRONMENT WOULD FAVOR
INTENSIFICATION SHOULD IT MATERIALIZE.  HOWEVER...AS IS OFTEN THE
CASE...THERE IS A FINE LINE BETWEEN A FAVORABLE AND UNFAVORABLE
ENVIRONMENT FOR STRENGTHENING. THE OFFICIAL FORECAST ASSUMES THERE
WILL BE SUFFICIENT SPACING BETWEEN THE UPPER-LEVEL LOW AND HANNA TO
PROMOTE STRENGTHENING. BY DAY 5...UPPER-LEVEL OUTFLOW FROM GUSTAV
COULD IMPART NORTHERLY SHEAR OVER HANNA POSSIBLY AFFECTING THE
INTENSITY.

HANNA HAS BEEN MOVING TOWARD THE WEST-NORTHWEST...OR 300/10...DURING
THE LAST 6 HOURS.  HOWEVER...A MOTION TOWARD THE NORTHWEST IS
EXPECTED OVER THE NEXT 2-3 DAYS AS HANNA MOVES AROUND THE
SOUTHWESTERN PERIPHERY OF THE SUBTROPICAL RIDGE.  THEREAFTER...THE
TRACK BECOMES MUCH LESS CERTAIN AS IT REMAINS TO BE SEEN HOW HANNA
WILL INTERACT WITH A MID-LATITUDE TROUGH FORECAST TO MOVE
OFF THE U.S. EAST COAST.  MOST OF THE DYNAMICAL MODELS SHOW HANNA
BEING LEFT BEHIND IN AN AREA OF WEAK STEERING.  HOWEVER...THE
TRADITIONALLY GOOD PERFORMING GFS FORECASTS HANNA TO TURN
NORTHEASTWARD AT DAYS 4 AND 5. THE OFFICIAL FORECAST ASSUMES THE
FORMER OF THOSE SCENARIOS AND SHOWS A SLOW WESTWARD TRACK.

FORECAST POSITIONS AND MAX WINDS

INITIAL      28/1500Z 20.5N  59.2W    35 KT
12HR VT     29/0000Z 21.4N  60.4W    40 KT
24HR VT     29/1200Z 22.8N  61.9W    45 KT
36HR VT     30/0000Z 24.4N  63.7W    55 KT
48HR VT     30/1200Z 25.7N  65.6W    60 KT
72HR VT     31/1200Z 27.0N  68.5W    70 KT
96HR VT     01/1200Z 27.5N  70.0W    75 KT
120HR VT     02/1200Z 27.5N  71.5W    70 KT

$$
FORECASTER RHOME




WTNT43 KNHC 282032
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT THU AUG 28 2008

AFTER LOOKING QUITE IMPRESSIVE IN SATELLITE IMAGERY THIS
MORNING...VERTICAL SHEAR HAS TAKEN ITS TOLL ON HANNA AND THE
LOW-LEVEL CIRCULATION HAS BECOME COMPLETELY EXPOSED.  WHILE IT IS
TEMPTING TO LOWER THE INTENSITY BASED ON THIS TREND...IT IS BEST TO
KEEP HANNA AS A MINIMAL TROPICAL STORM FOR THIS ADVISORY.  THE LACK
OF ORGANIZATION NOTWITHSTANDING...THE OVERALL FORECAST PHILOSOPHY
REMAINS UNCHANGED. DYNAMICAL MODELS INSISTS THAT THE UPPER-LEVEL
LOW CURRENTLY IMPARTING WESTERLY SHEAR OVER HANNA WILL BEGIN TO MOVE
WESTWARD ALLOWING A MORE FAVORABLE ENVIRONMENT FOR STRENGTHENING TO
DEVELOP OVER THE CYCLONE.  SIMILARLY...THE SHIPS AND LGEM MODELS
ARE BASING THEIR FORECAST ON A LOW SHEAR ENVIRONMENT.  ANALYSIS OF
WATER VAPOR IMAGERY INDICATES THAT THE UPPER-LEVEL LOW HAS NOT
BUDGED ALL DAY SO IT WOULD APPEAR THAT THE SHEAR WILL NOT RELAX IN
THE SHORT-TERM.  THIS IS THE BASIS FOR THE NEW OFFICIAL FORECAST
WHICH IS BELOW THE INTENSITY MODEL CONSENSUS.  IF THE UPPER-LOW
DOES EVENTUALLY MOVE OUT OF HANNA'S WAY...ENVIRONMENTAL CONDITIONS
WOULD FAVOR STRENGTHENING. BY DAY 5...UPPER-LEVEL OUTFLOW FROM
GUSTAV COULD IMPART NORTHERLY SHEAR OVER HANNA POSSIBLY AFFECTING
THE INTENSITY.

HANNA CONTINUES MOVING WEST-NORTHWESTWARD...OR 300/10.  HOWEVER...A
MOTION TOWARD THE NORTHWEST IS FORECAST OVER THE NEXT 2-3 DAYS AS
HANNA IS EXPECTED TO STRENGTHEN AND BECOMES A DEEPER SYSTEM.
THEREAFTER...THE TRACK FORECAST IS RIDDLED WITH UNCERTAINTY AS IT
IS UNCLEAR HOW HANNA WILL INTERACT WITH A MID-LATITUDE TROUGH
FORECAST TO MOVE OFF THE U.S. EAST COAST. MOST OF THE DYNAMICAL
MODELS SHOW THE TROUGH BYPASSING HANNA TO THE NORTH AND LEAVING IT
BEHIND IN AN AREA OF WEAK STEERING. SUCH AN EVOLUTION WOULD RESULT
IN ERRATIC OR LITTLE OVERALL MOTION. ACCORDINGLY...THE OFFICIAL
FORECAST SHOWS A SLOW WESTWARD MOTION AT DAYS 4 AND 5.  IT SHOULD BE
ADDED THAT THERE IS LARGER THAN NORMAL UNCERTAINTY ASSOCIATED WITH
BOTH THE TRACK AND INTENSITY FORECASTS OF HANNA.

FORECAST POSITIONS AND MAX WINDS

INITIAL      28/2100Z 20.7N  60.1W    35 KT
12HR VT     29/0600Z 21.7N  61.4W    35 KT
24HR VT     29/1800Z 23.4N  63.4W    40 KT
36HR VT     30/0600Z 24.9N  65.3W    50 KT
48HR VT     30/1800Z 25.9N  67.0W    60 KT
72HR VT     31/1800Z 27.0N  69.0W    70 KT
96HR VT     01/1800Z 27.5N  70.5W    70 KT
120HR VT     02/1800Z 27.5N  71.5W    65 KT

$$
FORECASTER RHOME




WTNT43 KNHC 290259
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT THU AUG 28 2008

AFTER WESTERLY MID- TO UPPER-LEVEL SHEAR PRODUCED AN EXPOSED
LOW-LEVEL CIRCULATION CENTER...CONVECTION HAS REDEVELOPED WITH A
VENGEANCE OVER OR NEAR THE CENTER CONTAINING CLOUD TOPS AS COLD AS
-83C. HOWEVER...THE CONVECTIVE DEVELOPMENT APPEARS TO BE A BURSTING
PATTERN...WHICH IS USUALLY SHORT-LIVED. THE ADVISORY INTENSITY IS
45 KT BASED ON A DVORAK T-NUMBER OF T3.0/45 KT FROM TAFB AND THE
CONTINUED CONVECTIVE DEVELOPMENT SINCE THE 00Z SATELLITE FIX TIME.

THE INITIAL MOTION ESTIMATE IS 290/06. HANNA HAD BEEN MOVING DUE
WEST AT ABOUT 10 KT...BUT THE 24-HOUR MOTION OF THE PRESSURE
ENVELOPE SURROUNDING THE CYCLONE CENTER HAS ONLY BEEN MOVING AT
AROUND 5 KT. THE PRIMARY STEERING MECHANISMS FOR THE NEXT 3 DAYS
WILL BE THE LARGE SUBTROPICAL HIGH TO THE NORTH OF HANNA AND THE
MID- TO UPPER-LEVEL LOW LOCATED ABOUT 275 NMI WEST OF HANNA. ALL OF
THE MODELS HAVE BEEN WEAKENING AND MOVING THE UPPER-LOW TO THE
SOUTHWEST TOO QUICKLY...WHICH IS LIKELY DUE TO THE FAST OUTFLOW
FROM GUSTAV GETTING ENTRAINED INTO THE LOW AND KEEPING IT STRONGER
THAN THE MODEL FORECASTS. HOWEVER...OUTFLOW FROM GUSTAV IS NOW
BEING SHUNTED SOUTHEASTWARD INTO THE EASTERN CARIBBEAN...SO A
WEAKENING TREND AND SOUTHWESTWARD MOTION BY THE UPPER-LOW IS
EXPECTED TO ENSUE WITHIN THE NEXT 24 HOURS. HANNA IS FORECAST TO
MOVE AROUND THE UPPER-LOW THROUGH 72-96 HOURS BEFORE IT ENCOUNTERS
STRONG MID- TO UPPER-LEVEL NORTHERLY WINDS BEHIND A POWERFUL
MID-TROPOSPHERIC TROUGH...WHICH IS FORECAST TO MOVE OFF THE U.S.
EAST COAST AT DAYS 4 AND 5. THAT DEVELOPING SCENARIO IS INDICATED
BY ALMOST ALL OF THE MODELS TO VARYING DEGREES...BUT ENOUGH TO
INDUCE SOME SOUTHWARD COMPONENT TO HANNA'S MOTION. MOST OF THE
MODEL GUIDANCE HAS HAD A FAST AND RIGHT-OF-TRACK BIAS THE PAST 36
HOURS...SO THE FORECAST TRACK FOR THIS ADVISORY WAS ADJUSTED TO THE
LEFT OF THE PREVIOUS TRACK AND THE NHC MODEL CONSENSUS.

MODERATE WESTERLY SHEAR HAS BEEN REPLACED BY LIGHT SOUTHERLY SHEAR
DURING THE PAST 6 HOURS NOW THAT THE UPPER-LOW HAS SHOWN SIGNS OF
WEAKENING AND MOVING FARTHER AWAY FROM HANNA. AS THE LOW CONTINUES
TO WEAKEN AND MOVES TO A POSITION TO THE SOUTHWEST OF HANNA...
UPPER-LEVEL OUTFLOW SHOULD IMPROVE TO THE NORTHWEST AIDING A STEADY
INTENSIFICATION. ALTHOUGH NOT INDICATED AT ANY OF THE FORECAST
TIMES... ATMOSPHERIC AND OCEANIC CONDITIONS ARE EXPECTED TO BECOME
QUITE FAVORABLE FOR SIGNIFICANT STRENGTHENING BETWEEN 72 AND 96
HOURS...AND HANNA COULD BECOME A MAJOR HURRICANE AS INDICATED BY
THE GFDL MODEL. THE OFFICIAL FORECAST IS A BLEND OF THE SHIPS AND
GFDL MODELS...AND IS SIMILAR TO THE LGEM MODEL.


FORECAST POSITIONS AND MAX WINDS

INITIAL      29/0300Z 21.1N  60.6W    45 KT
12HR VT     29/1200Z 21.8N  62.0W    50 KT
24HR VT     30/0000Z 23.2N  64.2W    55 KT
36HR VT     30/1200Z 24.6N  66.3W    60 KT
48HR VT     31/0000Z 25.7N  68.0W    70 KT
72HR VT     01/0000Z 26.6N  70.0W    80 KT
96HR VT     02/0000Z 26.5N  71.2W    80 KT
120HR VT     03/0000Z 26.0N  71.6W    75 KT

$$
FORECASTER STEWART/BEVEN




WTNT43 KNHC 290853
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT FRI AUG 29 2008

ALTHOUGH THE UPPER-LOW TO THE NORTHWEST OF HANNA HAS BEGUN TO MOVE
AWAY...IT IS STILL PRODUCING SHEAR OVER THE TROPICAL CYCLONE. ONCE
AGAIN THE CENTER HAS MOVED AWAY FROM THE DEEP CONVECTION WHICH IS
NOW CONFINED TO A CYCLONICALLY CURVED BAND IN THE EASTERN
SEMICIRCLE. DVORAK T-NUMBERS STILL SUPPORT AN INITIAL INTENSITY OF
45 KNOTS...BUT WITH THE CURRENT SHEARED PATTERN...THIS ESTIMATE
COULD BE GENEROUS. THE EVOLUTION OF THE UPPER-LEVEL LOW APPEARS TO
BE THE KEY PLAYER FOR BOTH THE INTENSITY AND TRACK OF HANNA FOR THE
NEXT 24 TO 48 HOURS. IF THE LOW WEAKENS AND MOVES AWAY AS INDICATED
BY GLOBAL MODELS...THE ENVIRONMENT BECOMES MORE FAVORABLE FOR
STRENGTHENING. THE OFFICIAL FORECAST ASSUMES A GOOD SOLUTION FROM
GLOBAL MODELS AND CALLS FOR A GRADUAL INTENSIFICATION FROM 24 TO 72
HOURS. THE FORECAST IS SIMILAR TO THE SHIPS MODEL BUT DOES NOT
SHOWS AS MUCH STRENGTHENING AS SUGGESTED BY THE GFDL AND HWRF.

HANNA HAS BEEN MOVING AROUND THE EAST SIDE OF THE UPPER-LOW AND THE
BEST ESTIMATE OF THE INITIAL MOTION IS 310 DEGREES AT 12 KNOTS. A
GENERAL NORTHWEST TO WEST-NORTHWEST MOTION IS EXPECTED DURING THE
NEXT 2 TO 3 DAYS WHILE THE CYCLONE IS EMBEDDED WITHIN THE FLOW
BETWEEN THE UPPER LOW AND THE SUBTROPICAL RIDGE. BEYOND 3
DAYS...MOST OF THE GLOBAL MODELS ARE CARVING A LARGE TROUGH OVER
THE CENTRAL ATLANTIC AND DEVELOPING A LARGE RIDGE OVER THE EASTERN
UNITED STATES. THIS PATTERN SHOULD FORCE HANNA ON A SLOW
SOUTHWESTERLY TRACK BEYOND THREE DAYS...BUT AT THE SAME TIME THE
UPPER-LEVEL WINDS SHOULD WEAKEN THE CYCLONE. THE OFFICIAL FORECAST
SHOWS A LITTLE BIT OF THE SOUTHWESTERLY MOTION BUT DOES NOT GO AS
FAR SOUTH AS SHOWN BY MOST OF THE MODELS. IN FACT...THE GFS HAS
JOINED THE REST OF THE GLOBAL MODELS IN BRINGING THE CYCLONE
SOUTHWESTWARD. I PREFER TO WAIT FOR MORE MODEL RUNS BEFORE FORECAST
SUCH A RARE BUT NOT UNIQUE TRACK TOWARD THE SOUTHWEST.


FORECAST POSITIONS AND MAX WINDS

INITIAL      29/0900Z 21.7N  62.3W    45 KT
12HR VT     29/1800Z 22.6N  64.0W    45 KT
24HR VT     30/0600Z 24.0N  66.0W    50 KT
36HR VT     30/1800Z 25.3N  68.3W    60 KT
48HR VT     31/0600Z 26.0N  70.0W    70 KT
72HR VT     01/0600Z 26.0N  71.5W    80 KT
96HR VT     02/0600Z 25.5N  72.2W    80 KT
120HR VT     03/0600Z 25.0N  73.0W    75 KT

$$
FORECASTER AVILA




WTNT43 KNHC 291453
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT FRI AUG 29 2008

A 1031 UTC QUIKSCAT OVERPASS WAS VERY HELPFUL IN LOCATING THE CENTER
OF HANNA EARLY THIS MORNING.  VISIBLE IMAGERY SHOWED THAT THE CENTER
BRIEFLY BECAME EXPOSED...HOWEVER...NEW CONVECTION FORMED SINCE THAT
TIME AND THE CENTER IS POSITIONED JUST BENEATH THE COLDER CLOUD
TOPS.  DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB CONTINUE TO
SUPPORT 45 KT...SO THE INITIAL INTENSITY REMAINS UNCHANGED.  IN THE
NEAR TERM...THE DYNAMICAL MODELS SUGGEST THAT THE UPPER-LOW TO THE
WEST-NORTHWEST OF HANNA WILL MOVE WESTWARD AND WEAKEN...WHICH
SHOULD RELAX THE SOUTHWESTERLY SHEAR THAT IS CURRENTLY IMPINGING
UPON THE CYCLONE.  THE INTENSITY FORECAST FOLLOWS THIS SOLUTION
AND CALLS FOR GRADUAL STRENGTHENING DURING THE NEXT 2 DAYS...
BRINING HANNA TO HURRICANE STATUS.  THEREAFTER THERE IS A LARGE
AMOUNT OF UNCERTAINTY IN THE INTENSITY FORECAST. THE GLOBAL MODELS
PREDICT STRONG NORTHWEST TO NORTH UPPER-LEVEL WINDS OVER
HANNA...WHICH ONE WOULD THINK SHOULD HALT ADDITIONAL STRENGTHENING
OR EVEN WEAKEN THE STORM.  HOWEVER...NEARLY ALL OF THE INTENSITY
GUIDANCE SHOW STRENGTHENING OR LITTLE INTENSITY CHANGE DURING THAT
TIME.  ASSUMING THAT THE SHEAR WILL PRODUCE A NEGATIVE AFFECT ON
HANNA...THE NEW INTENSITY FORECAST FOLLOWS PERSISTENCE OF PREVIOUS
ADVISORY AND IS A LITTLE BELOW MOST OF THE GUIDANCE.

HANNA MOVED WEST-NORTHWESTWARD DURING THE PAST 12 HOURS AND THE
INITIAL MOTION ESTIMATE IS 285/10.  THE TRACK GUIDANCE IS
IN GOOD AGREEMENT THROUGH 48 HOURS ON A WEST-NORTHWEST TO NORTHWEST
MOTION.  THEREAFTER...THE MODELS GENERALLY SHOW A WEST-
SOUTHWESTWARD OR SOUTHWARD TURN..SOUTH OF A BUILDING RIDGE OVER
THE EASTERN UNITED STATES.  HOWEVER...THE SHARPNESS OF THE TURN
AND SPEED OF MOTION VARIES GREATLY.  THE NEW NHC TRACK HAS BEEN
ADJUSTED SOUTHWARD DURING THE FIRST COUPLE OF DAYS...MAINLY DUE TO
THE MORE WESTWARD INITIAL MOTION.  THIS IS IN CLOSE AGREEMENT WITH
THE MODEL CONSENSUS.  AFTER 72 HOURS...THE NEW TRACK IS A LITTLE
FASTER THAN THE PREVIOUS ADVISORY...BUT IS NOTICEABLY SLOWER THAN
THE UKMET AND GFDL MODELS.  THE HWRF...WHICH SHOWS A CYCLONIC LOOP
NORTH OF THE BAHAMAS AND A NORTHEASTWARD MOTION AT DAY 5...IS
CONSIDER AN OUTLIER AT THIS TIME.

INTERESTS IN THE SOUTHWESTERN BAHAMAS AND TURKS AND CAICOS SHOULD
MONITOR THE PROGRESS OF HANNA.  IMPACTS IN THESE AREAS COULD OCCUR
MUCH SOONER THAN INDICATED BY THE EXACT TRACK...ESPECIALLY IF THE
MORE NORTHWESTWARD MOTION DOES NOT MATERIALIZED LATER TODAY OR ON
SATURDAY.


FORECAST POSITIONS AND MAX WINDS

INITIAL      29/1500Z 21.3N  62.7W    45 KT
12HR VT     30/0000Z 22.2N  64.5W    50 KT
24HR VT     30/1200Z 23.6N  66.7W    55 KT
36HR VT     31/0000Z 24.6N  68.6W    60 KT
48HR VT     31/1200Z 25.1N  70.1W    70 KT
72HR VT     01/1200Z 24.7N  71.6W    65 KT
96HR VT     02/1200Z 24.0N  72.5W    65 KT
120HR VT     03/1200Z 23.0N  73.5W    60 KT

$$
FORECASTER BROWN




WTNT43 KNHC 292054
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT FRI AUG 29 2008

THE CENTER OF HANNA REMAINS NEAR THE WESTERN EDGE OF THE RATHER
SHAPELESS AREA OF DEEP CONVECTION SEEN IN SATELLITE IMAGERY.  A
1412 UTC ASCAT PASS FOUND WINDS OF 40 KT OVER THE NORTHEASTERN
SEMICIRCLE.  GIVEN THE LOW BIAS TYPICAL OF ASCAT WINDS IN THIS
RANGE...IT SUPPORTS MAINTAINING THE INITIAL INTENSITY AT 45 KT.
THIS INTENSITY IS ALSO SUPPORTED BY SATELLITE ESTIMATES FROM
TAFB AND SAB WHICH REMAIN T3.0 OR 45 KT.

WATER VAPOR IMAGERY SHOWS THAT THE UPPER-LEVEL LOW LOCATED A
COUPLE HUNDRED MILES WEST-NORTHWEST OF HANNA HAS NOT BUDGED
TODAY AND IT CONTINUES TO IMPART SOUTHWESTERLY SHEAR ON THE
TROPICAL CYCLONE.  THE DYNAMICAL MODELS REMAIN EMPHATIC
SUGGESTING THAT THE UPPER-LOW WILL MOVE WEST OR WEST-
SOUTHWESTWARD AND WEAKEN...ALLOWING HANNA TO GRADUALLY
STRENGTHEN.  THE NEW NHC INTENSITY FORECAST CONTINUES TO ALLOW FOR
SOME STRENGTHENING DURING THE NEXT COUPLE DAYS BUT SHOWS A LOWER
PEAK INTENSITY THAN WAS FORECAST IN THE PREVIOUS ADVISORY.  IN
ABOUT 3 DAYS...THE MODELS CONTINUE TO FORECAST STRONG NORTHWEST TO
NORTH UPPER-LEVEL WINDS OVER THE WESTERN ATLANTIC.  THESE WINDS ARE
PARTIALLY THE RESULT OF OUTFLOW FROM GUSTAV.  DESPITE THE HOSTILE
UPPER-LEVEL WIND FORECAST...THE INTENSITY GUIDANCE DOES NOT PREDICT
WEAKENING.  OUR INTENSITY FORECAST REMAINS ON THE LOW SIDE OF THE
GUIDANCE AND STILL ASSUMES THAT THE NORTHERLY SHEAR WILL HAVE A
NEGATIVE IMPACT ON HANNA'S INTENSITY.

HANNA CONTINUES MOVING WEST-NORTHWESTWARD OR 295/9.  IN
GENERAL...THE FORECAST GUIDANCE HAS COME INTO A LITTLE BETTER
AGREEMENT ON THE FUTURE TRACK OF HANNA.  THE TROPICAL STORM IS
FORECAST TO CONTINUE WEST-NORTHWESTWARD DURING THE NEXT 2
DAYS...FOLLOWED BY A TURN TOWARD THE WEST-SOUTHWEST.  THE HWRF
CONTINUES TO BE AN OUTLIER SHOWING A CYCLONIC LOOP NORTH OF THE
SOUTHEASTERN BAHAMAS.  THE NEW TRACK FORECAST IS VERY SIMILAR TO
THE PREVIOUS FORECAST THROUGH 48 HOURS...BUT IS A LITTLE FASTER
AND FARTHER WEST THEREAFTER.

FORECAST POSITIONS AND MAX WINDS

INITIAL      29/2100Z 21.8N  63.8W    45 KT
12HR VT     30/0600Z 22.8N  65.4W    50 KT
24HR VT     30/1800Z 24.0N  67.7W    55 KT
36HR VT     31/0600Z 24.8N  69.8W    60 KT
48HR VT     31/1800Z 25.0N  71.1W    65 KT
72HR VT     01/1800Z 24.5N  72.5W    65 KT
96HR VT     02/1800Z 23.7N  73.7W    60 KT
120HR VT     03/1800Z 23.0N  75.0W    60 KT

$$
FORECASTER BROWN




WTNT43 KNHC 300259
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT FRI AUG 29 2008

CONVENTIONAL SATELLITE IMAGERY SUGGESTS THAT HANNA REMAINS WITHIN A
VERY HARSH VERTICAL WIND SHEAR ENVIRONMENT.  THE SURFACE
CIRCULATION...EXPOSED WELL WEST OF THE REMAINING CONVECTIVE
BAND...PASSED ABOUT 60 MILES NORTH OF BUOY 41043 WHICH RECORDED A
SEA LEVEL PRESSURE OF 1004 MB.  CONSEQUENTLY...HANNA'S CENTRAL
PRESSURE IS INCREASED SLIGHTLY TO 1002 MB BASED ON THIS DATA.  A
QUIKSCAT OVERPASS JUST CAME IN A FEW MINUTES AGO AND INDICATED THAT
THE CIRCULATION MAY BE JUST A BIT SOUTH OF THE ADVISORY POSITION AS
WELL AS ALSO REVEALING A FEW BELIEVABLE 40-45 KT WINDS OVER THE
NORTHEAST QUADRANT.  THEREFORE...THE INITIAL INTENSITY IS HELD AT
45 KT.  THE GLOBAL MODELS CONTINUE TO INDICATE THAT THE UPPER-LEVEL
LOW LOCATED A FEW HUNDRED MILES WEST-NORTHWEST OF CYCLONE WILL
EITHER INCREASE IN DISTANCE BETWEEN THE TWO FEATURES WITH TIME OR
WEAKEN AND OPEN UP INTO A TROUGH.  THE SHIPS MODEL FOLLOWS SUIT BY
SUGGESTING THAT THE SHEAR WILL DECREASE IN 12 TO 24 HOURS...WHICH
IS REFLECTED IN THE INTENSITY FORECAST WITH GRADUAL STRENGTHENING
THROUGH THE 72 HOUR PERIOD.  THROUGH THE REMAINING PORTION OF THE
FORECAST...THE LARGE-SCALE MODELS SHOW STRONG NORTH TO
NORTHWESTERLY UPPER-LEVEL WINDS SETTING UP OVER THE WESTERN
ATLANTIC...WHICH COULD ALSO BE INFLUENCED BY HURRICANE GUSTAV'S
OUTFLOW PATTERN.  SINCE THERE IS A CONSENSUS IN THE DEVELOPMENT OF
AN INHIBITING SYNOPTIC UPPER-LEVEL PATTERN...A WEAKENING IS
INDICATED THROUGH DAY 5.

INITIAL MOTION IS ESTIMATED AT 295/12...WITHIN THE DEEP LAYER
EAST-SOUTHEASTERLY FLOW OF THE SUBTROPICAL RIDGE TO THE NORTH OF
THE CYCLONE.  THE FORECAST PHILOSOPHY REMAINS INTACT FROM THE
PREVIOUS ADVISORY...WHICH FOLLOWS CLOSELY TO THE DYNAMICAL MODEL
BLEND THROUGH 72 HOURS.  BEYOND THE DAY 3 PERIOD...THE OFFICIAL
FORECAST IS NUDGED TOWARD THE PREVIOUS TRACK AND A BLEND OF THE GFS
AND UKMET MODELS WHICH APPEAR TO BE DEPICTING THE SHEARED VERTICAL
STRUCTURE OF THE SYSTEM MORE ACCURATELY.

FORECAST POSITIONS AND MAX WINDS

INITIAL      30/0300Z 22.1N  65.3W    45 KT
12HR VT     30/1200Z 22.9N  67.0W    50 KT
24HR VT     31/0000Z 23.9N  69.2W    55 KT
36HR VT     31/1200Z 24.5N  70.8W    60 KT
48HR VT     01/0000Z 24.6N  72.1W    65 KT
72HR VT     02/0000Z 24.4N  73.4W    65 KT
96HR VT     03/0000Z 23.6N  75.0W    60 KT
120HR VT     04/0000Z 23.0N  76.3W    55 KT

$$
FORECASTER ROBERTS




WTNT43 KNHC 300857
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT SAT AUG 30 2008

THERE HAS BEEN NO SIGNIFICANT CHANGE IN THE CLOUD PATTERN OF HANNA.
THE CENTER CONTINUES TO RUN AWAY FROM THE CONVECTION AND NEW
THUNDERSTORM ACTIVITY REDEVELOPS OVER IT. THIS MEANS THAT THE SHEAR
HAS NOT RELAXED YET. A NOAA BUOY...41043...HAS BEEN EXTREMELY USEFUL
IN TRACKING THE CYCLONE.  IT HAS DEPICTED THE WELL-DEFINED SURFACE
CIRCULATION ASSOCIATED WITH HANNA AND HAS RECENTLY
REPORTED A MINIMUM PRESSURE OF NEAR 1002 MB. AS LONG AS THE
MODERATE SHEAR PREVAILS...CAUSED BY THE RESILIENT UPPER-LOW...HANNA
MOST LIKELY WILL NOT STRENGTHEN. THE OFFICIAL FORECAST CALLS FOR NO
CHANGE
IN INTENSITY DURING THE NEXT 12 HOURS OR SO. GLOBAL MODELS INSIST
ON WEAKENING THE UPPER-LOW...CREATING A MORE FAVORABLE ENVIRONMENT
FOR HANNA TO STRENGTHEN IN THE PERIOD BETWEEN 12 AND 48 HOURS.
THEREAFTER...THE SHEAR IS FORECAST TO INCREASE AND THIS IS
REFLECTED IN THE OFFICIAL FORECAST BY SHOWING SOME SLIGHT
WEAKENING. MOST OF THE MODELS CONTINUE TO INTENSIFY HANNA...SOME OF
THEM QUITE SIGNIFICANTLY...DESPITE THE SHEAR. I DO NOT HAVE AN
EXPLANATION FOR IT.

THE CENTER IS VERY DIFFICULT TO LOCATE ON IR IMAGES BUT SATELLITE
FIXES AND DATA FROM THE NOAA BUOY SUGGEST THAT HANNA HAS BEEN
MOVING WESTWARD OR 280 DEGREES AT 10 KNOTS. FOR ABOUT 12 TO 24
HOURS...A WEST-NORTHWEST MOTION AROUND THE UPPER-LOW IS
ANTICIPATED. THEREAFTER...A STRONG SUBTROPICAL HIGH WHICH IS
FORECAST TO BUILD TO THE NORTH OF HANNA WILL THEN PROVIDE THE
DOMINANT STEERING FLOW. THIS SHOULD FORCE THE CYCLONE ON A
WESTWARD AND THEN AN EVEN SLOWER WEST-SOUTHWESTWARD TRACK. I TRIED
VERY HARD NOT TO FORECAST THE WEST-SOUTHWEST TURN SINCE THIS IS NOT
A VERY COMMON TROPICAL CYCLONE TRACK BUT RELIABLE DYNAMICAL
GUIDANCE HAS FORCED ME TO DO SO. THE OFFICIAL FORECAST IS
PRACTICALLY ON TOP OF THE MODEL CONSENSUS.  I ALWAYS WONDERED HOW
TODAY'S SOPHISTICATED DYNAMICAL MODELS WOULD HAVE FORECAST
HURRICANE BETSY BACK IN 1965. THIS HURRICANE MOVED SOUTHWESTWARD
OVER THE BAHAMAS.


FORECAST POSITIONS AND MAX WINDS

INITIAL      30/0900Z 21.9N  66.3W    45 KT
12HR VT     30/1800Z 22.6N  68.0W    45 KT
24HR VT     31/0600Z 23.3N  70.0W    50 KT
36HR VT     31/1800Z 23.5N  71.5W    60 KT
48HR VT     01/0600Z 23.5N  72.5W    65 KT
72HR VT     02/0600Z 23.5N  74.0W    65 KT
96HR VT     03/0600Z 23.0N  75.5W    60 KT
120HR VT     04/0600Z 22.5N  77.0W    55 KT

$$
FORECASTER AVILA



000

WTNT43 KNHC 301447
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT SAT AUG 30 2008

HANNA CONTINUES TO PRODUCE A LARGE AREA OF DEEP CONVECTION WITH
CLOUD TOP TEMPERATURES BELOW -80 DEGREES C. HOWEVER...THE CENTER OF
THE TROPICAL CYCLONE IS LOCATED NEAR THE SOUTHWESTERN EDGE OF THIS
CONVECTION.  THE EXACT CENTER HAS BEEN DIFFICULT TO LOCATE AS A
COUPLE OF SMALL VORTICES HAVE BEEN SEEN ROTATING AROUND THE LARGER
CIRCULATION THIS MORNING.  SATELLITE INTENSITY ESTIMATES REMAIN
T3.0 OR 45 KT AND AN EARLIER QUIKSCAT PASS SUGGEST MAXIMUM WINDS
WERE NEAR THAT VALUE.  THERE WERE SOME STRONGER WINDS SEEN IN THE
QUIKSCAT DATA...BUT THESE WINDS WERE WELL REMOVED FROM THE CENTER
AND APPEAR TO HAVE BEEN RAIN-INFLATED.

THE SOMEWHAT UNCERTAIN INITIAL MOTION ESTIMATE IS 275/7.  HANNA HAS
CONTINUED TO MOVE MORE WESTWARD DURING THE PAST 12-24 HOURS...WHICH
HAS REQUIRED A LITTLE SOUTHWARD ADJUSTMENT TO THE TRACK FORECAST IN
THE SHORT-TERM.  THE TRACK GUIDANCE PREDICTS A GENERAL WEST TO
WEST-NORTHWEST MOTION DURING THE NEXT 24-36 HOURS.  THEREAFTER...
THERE IS A GREAT DEAL OF SPREAD AMONG THE MODELS...AS A STRONG HIGH
PRESSURE RIDGE BUILDS OVER THE EASTERN UNITED STATES.  THE GFDL AND
HWRF RESPOND BY SHOWING A VERY SLOW AND ERRATIC MOTION IN ABOUT 3
DAYS...WHILE THE UKMET TURNS HANNA SOUTHWESTWARD TOWARDS EASTERN
CUBA.  VERY LATE IN THE PERIOD...THE HIGH OVER THE EASTERN U.S. IS
FORECAST TO MOVE OFF THE EAST COAST INTO THE WESTERN ATLANTIC AND
SEVERAL OF THE FORECAST MODELS NOW INDICATE A WEST-NORTHWESTWARD
AROUND DAY 5.  THE NEW FORECAST WHICH IS VERY SIMILAR TO THE
PREVIOUS ADVISORY...BUT SMOOTHS THROUGH THESE POSSIBLE UNDULATIONS
AND SHOWS A SLOW WESTWARD MOTION BETWEEN 72-120 HOURS. THE NEW
TRACK IS GENERALLY ALONG OR JUST SOUTH OF THE MODEL CONSENSUS.

THE MUCH DISCUSSED UPPER-LOW JUST WEST OF THE STORM APPEARS TO HAVE
WEAKENED A LITTLE THIS MORNING.  THE SHIPS GUIDANCE SUGGESTS THE
WESTERLY SHEAR MAY RELAX JUST A LITTLE OVER THE NEXT 24 HOURS.
GIVEN THE RESILIENCE OF HANNA...THE OFFICIAL FORECAST SHOWS A
LITTLE STRENGTHENING DURING THE NEXT DAY OR SO.
THEREAFTER...STRONG NORTHWEST TO NORTH UPPER-LEVEL WINDS ARE
FORECAST...SO THE OFFICIAL INTENSITY FORECAST NOW KEEPS HANNA JUST
BELOW HURRICANE STRENGTH.  IT SHOULD BE NOTED ONCE AGAIN...THAT THE
NHC INTENSITY FORECAST REMAINS BELOW ALL OF THE RELIABLE GUIDANCE.

BASED ON THE NEW FORECAST TRACK...THE GOVERNMENT OF THE BAHAMAS HAS
ISSUED A TROPICAL STORM WATCH FOR THE SOUTHEASTERN BAHAMAS AND
TURKS AND CAICOS ISLANDS.

FORECAST POSITIONS AND MAX WINDS

INITIAL      30/1500Z 21.9N  66.4W    45 KT
12HR VT     31/0000Z 22.4N  67.9W    50 KT
24HR VT     31/1200Z 22.9N  69.6W    55 KT
36HR VT     01/0000Z 23.2N  71.0W    60 KT
48HR VT     01/1200Z 23.2N  72.1W    60 KT
72HR VT     02/1200Z 23.0N  73.5W    55 KT
96HR VT     03/1200Z 23.0N  75.0W    55 KT
120HR VT     04/1200Z 23.0N  76.5W    55 KT

$$
FORECASTER BROWN




WTNT43 KNHC 302048
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT SAT AUG 30 2008

THE CLOUD PATTERN OF HANNA HAS CHANGED QUITE A BIT DURING THE DAY
TODAY.  THE TROPICAL STORM HAS BECOME INVOLVED WITH THE UPPER-LEVEL
LOW THAT WAS LOCATED TO ITS WEST...AND HANNA NOW HAS SOME
RESEMBLANCE OF A SUB-TROPICAL CYCLONE.  EVEN THOUGH THE CENTER IS
LOCATED WELL SOUTHWEST OF THE THUNDERSTORM ACTIVITY...BANDING OVER
THE NORTHEASTERN SEMICIRCLE STILL YIELD INTENSITY ESTIMATES OF T3.0
OR 45 KT FROM BOTH AGENCIES.

HANNA HAS BEEN MOVING BETWEEN THE WEST AND WEST-NORTHWEST AT
ABOUT 7 KT TODAY.  A SIMILAR MOTION IS FORECAST BY THE NUMERICAL
MODEL GUIDANCE FOR THE NEXT 24-36 HOURS...SO VERY LITTLE CHANGE WAS
NEEDED TO THE PREVIOUS FORECAST DURING THAT TIME.  THEREAFTER...THE
MODEL SPREAD HAS BECOME EXTREMELY LARGE AS A STRONG HIGH PRESSURE
RIDGE BUILDS OVER THE EASTERN UNITED STATES.  THE TRACK GUIDANCE NOW
PREDICTS A SLOW AND ERRATIC MOTION OF HANNA DURING THE 48 TO ABOUT
96 HOUR TIME FRAME.  THE GFDL AND HWRF BOTH PREDICT HANNA TO MAKE A
CYCLONIC LOOP NEAR THE SOUTHEASTERN BAHAMAS.  MEANWHILE...THE ECMWF
AND UKMET SHOW A SOUTHWESTWARD MOTION...WITH THE LATTER MODEL
FORECASTING HANNA TO BE OVER EASTERN CUBA.  BEYOND 96 HOURS...
NEARLY ALL OF THE GUIDANCE...EXCEPT THE UKMET...NOW FORECAST A
WEST-NORTHWESTWARD OR NORTHWESTWARD MOTION TO RESUME AS THE RIDGE
OVER THE EASTERN UNITED STATES WEAKENS.  WITH ALL OF THAT SAID...
THERE IS VERY LOW CONFIDENCE IN THE TRACK FORECAST.  THE NEW TRACK
SLOWS DOWN THE STORM CONSIDERABLY...AND NOW PREDICTS A SLOW
WEST-NORTHWESTWARD MOTION LATE IN THE PERIOD.  THE NHC TRACK IS A
LITTLE SOUTH OF THE CONSENSUS...ESPECIALLY AT DAY 5...BUT IS IN
GENERAL AGREEMENT WITH THE 12Z ECMWF.

GIVEN ALL THE UNCERTAINTIES IN THE TRACK FORECAST...THE INTENSITY
FORECAST SEEMS JUST AS DIFFICULT.  THE DYNAMICAL MODELS AND SHIPS
GUIDANCE SUGGEST THAT WEST TO NORTHWESTERLY SHEAR WILL CONTINUE
DURING THE NEXT 24-36 HOURS...FOLLOWED BY AN INCREASE IN NORTHERLY
SHEAR.  GIVEN THE UNCERTAINTIES AS TO HOW HANNA WILL RESPOND TO THE
SHEAR...THE INTENSITY FORECAST ALLOWS FOR SOME STRENGTHENING IN THE
SHORT-TERM...BUT LEVELS OFF THE INTENSITY BETWEEN 36-96 HOURS.
THERE ARE SOME INDICATIONS THAT THE UPPER-LEVEL ENVIRONMENT COULD
BECOME MORE CONDUCIVE VERY LATE IN THE PERIOD...SO SLIGHT
STRENGTHENING IS INDICATE AT DAY 5.  THE NHC FORECAST REMAINS BELOW
ALL OF THE RELIABLE INTENSITY GUIDANCE.

THE 12-FT SEA RADII WERE ADJUSTED OUTWARD OVER THE NORTHWESTERN
SEMICIRCLE BASED ON REPORTS FROM NOAA BUOY 41046.

FORECAST POSITIONS AND MAX WINDS

INITIAL      30/2100Z 22.4N  67.2W    45 KT
12HR VT     31/0600Z 22.8N  68.6W    45 KT
24HR VT     31/1800Z 23.3N  70.2W    50 KT
36HR VT     01/0600Z 23.5N  71.4W    55 KT
48HR VT     01/1800Z 23.5N  72.1W    55 KT
72HR VT     02/1800Z 23.5N  72.8W    55 KT
96HR VT     03/1800Z 24.0N  74.0W    55 KT
120HR VT     04/1800Z 25.0N  76.5W    60 KT

$$
FORECASTER BROWN



000

WTNT43 KNHC 310244
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT SAT AUG 30 2008

ENHANCED INFRARED IMAGERY AND MICROWAVE OVERPASSES DEPICT A
CONVECTIVELY CHALLENGED TROPICAL CYCLONE.  THE VERTICAL STRUCTURE
OF THE HANNA HAS TRANSFORMED INTO A SYSTEM SIMILAR TO A SUBTROPICAL
CYCLONE...WITH A SLIGHT TILT TO THE WEST WITH HEIGHT.  THE CYCLONE
HAS BEEN STRUGGLING TO MAINTAIN DEEP CONVECTION NEAR THE PARTLY
EXPOSED CENTER...PARTICULARLY OVER THE WEST AND SOUTH QUADRANTS.
THERE APPEARS TO BE SOME MODERATE SUBSIDENCE SPREADING OVER THE
AREA PRODUCED BY CONVERGING UPPER-LEVEL WINDS BETWEEN THE UPPER LOW
NOW ASSOCIATED WITH HANNA AND GUSTAV'S OUTFLOW PATTERN...WITH THIS
DRYER MORE STABLE AIR BEING ENTRAINED INTO THE SYSTEM'S CORE.  THE
INITIAL INTENSITY IS HELD AT 45 KT BASED ON DVORAK AND
HEBERT/POTEAT INTENSITY TECHNIQUES...AS WELL AS A QUIKSCAT PASS
THAT SUPPORTED THIS INTENSITY.

THE INTENSITY MODELS CONTINUE TO INDICATE AN INCREASE IN NORTHERLY
SHEAR AROUND THE 24 HOUR PERIOD...THEN TRANSITIONING TO A MORE
SOUTH TO SOUTHWESTERLY COMPONENT AFTERWARD.  THE SHIPS AND THE LGEM
AGREE WITH GRADUAL STRENGTHENING UNTIL THE STRONG NORTHERLY SHEAR
APPEARS...THEN THE MODELS AGREE WITH LITTLE CHANGE THROUGH THE 72
HOUR PERIOD.  BEYOND DAY 3...THE DYNAMICAL MODELS INDICATE A HINT
OF A MORE FAVORABLE UPPER WIND ENVIRONMENT...WHICH THE
AFOREMENTIONED MODELS ALSO DEPICT.  THE OFFICIAL FORECAST FOLLOWS
THIS PHILOSOPHY AND INDICATES SLIGHT INTENSIFICATION AT THE 120
HOUR PERIOD.

THE INITIAL MOTION IS ESTIMATED AT 300/7.  DYNAMICAL MODELS SUGGEST
THAT AN ANCHORED SUBTROPICAL RIDGE TO THE NORTH OF THE CYCLONE
SHOULD INFLUENCE A GENERAL WEST-NORTHWESTWARD MOTION DURING THE
NEXT 48 HOURS.  AFTERWARD...A DEEP MID-LATITUDE LOW AND ASSOCIATED
TROUGH IS EXPECTED TO MOVE OVER THE WESTERN ATLANTIC AND WEAKEN A
PORTION OF THE RIDGE LOCATED OVER SOUTHEAST U.S. AND THE BAHAMAS
WHILE A HIGH AMPLITUDE BLOCKING HIGH SETS UP OVER THE EASTERN
SEABOARD.  THIS PARTICULAR PATTERN IS EXPECTED TO CAUSE HANNA TO
TEMPORARILY SLOW ITS FORWARD SPEED THROUGH THE 72 HOUR PERIOD WHILE
MAINTAINING A WEST-NORTHWESTWARD TRACK.  THROUGH THE REMAINDER OF
THE FORECAST...A MID-LEVEL RIDGE IS FORECAST TO BUILD NORTHEAST OF
HANNA IN RESPONSE TO THE AFOREMENTIONED MID-LATITUDE LOW LIFTING OUT
AND MOVING AWAY FROM THE NORTHEAST COAST.  THE MODEL SPREAD REMAINS
RATHER LARGE...HOWEVER...THE MAJORITY ARE SHOWING A TURN TOWARD THE
NORTHWEST OVER OR EAST OF THE BAHAMAS BEYOND 72 HOURS...WHILE THE
UKMET IS STILL PREDICTING THE SUBTROPICAL RIDGE TO REMAIN INTACT
TO THE NORTH.  THE OFFICIAL FORECAST FOLLOWS THE MODEL CONSENSUS
AND IS SIMILAR TO THE PREVIOUS ADVISORY BUT INDICATES A MORE
NORTHWESTWARD MOTION BEYOND DAY 3.

FORECAST POSITIONS AND MAX WINDS

INITIAL      31/0300Z 22.9N  67.8W    45 KT
12HR VT     31/1200Z 23.3N  69.0W    45 KT
24HR VT     01/0000Z 23.6N  70.4W    50 KT
36HR VT     01/1200Z 23.6N  71.4W    55 KT
48HR VT     02/0000Z 23.6N  72.2W    55 KT
72HR VT     03/0000Z 23.8N  73.1W    55 KT
96HR VT     04/0000Z 24.5N  74.5W    55 KT
120HR VT     05/0000Z 26.5N  76.5W    60 KT

$$
FORECASTER ROBERTS/BEVEN




WTNT43 KNHC 310855
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT SUN AUG 31 2008

HANNA HAS BEEN GOING THROUGH SOME STRUCTURAL CHANGES THAT HAVE
RESEMBLED A SUBTROPICAL CYCLONE AT TIMES AS AN UPPER-LEVEL COLD LOW
AND DRY AIR HAVE BECOME ENTANGLED WITH THE INNER-CORE CIRCULATION.
HOWEVER...DURING THE PAST 6 HOURS WATER VAPOR IMAGERY HAS INDICATED
THAT THE UPPER-LOW HAS BEGUN TO DROP SOUTHWARD TOWARD HISPANIOLA
...WHICH MAY ALLOW HANNA TO TRANSITION BACK INTO A FULL WARM CORE
TROPICAL CYCLONE LATER TODAY. THE INTENSITY WAS INCREASED TO 50 KT
AND THE WIND RADII WERE EXPANDED SIGNIFICANTLY IN THE NORTHERN
SEMICIRCLE BASED ON A 30/2231Z QUIKSCAT OVERPASS THAT WAS NOT
AVAILABLE FOR THE PREVIOUS ADVISORY. SATELLITE ESTIMATES FROM TAFB
AND SAB ARE ST3.0/45 KT.

THE INITIAL MOTION ESTIMATE AT 290/10. ALL OF THE NHC MODEL GUIDANCE
NOW INDICATES SOME SOUTHWARD COMPONENT TO HANNA'S TRACK BY 48 HOURS
AS STRONG NORTHERLY FLOW IMPINGES ON THE CYCLONE BEHIND A DIGGING
TROUGH OFF THE U.S. EAST COAST COMBINED WITH OUTFLOW FROM HURRICANE
GUSTAV LOCATED WELL TO THE WEST OF HANNA. THE SHIPS MODEL INDICATES
AT LEAST 30 KT OF NORTHERLY SHEAR ACROSS HANNA AT 48 HOURS...WHICH
SHOULD ACT TO DISPLACE ANY DEEP CONVECTION INTO THE SOUTHERN
SEMICIRCLE AND ALSO HELP TO FORCE THE CYCLONE SOUTHWARD. SHOULD
HANNA BE STRIPPED OF ALL CONVECTION AROUND THAT TIME PERIOD...THE
SHALLOW BAM MODEL ALSO INDICATES A SOUTHWARD COMPONENT OF MOTION
...INCLUDING A CYCLONIC LOOP. HOWEVER...BY 96 HOURS... NEARLY ALL OF
THE MODELS FORECAST THE STRONG UPPER-TROUGH TO LIFT OUT TO THE
NORTHEAST AND BE REPLACED BY A LARGE RIDGE TO THE NORTH AND EAST OF
HANNA. THE LATTER FEATURE IS EXPECTED TO GRADUALLY INDUCE A
NORTHWESTWARD COMPONENT OF MOTION BY DAYS 4 AND 5. THE KEY TO THE
FORECAST TRACK AT THOSE FORECAST TIMES WILL BE JUST HOW FAR SOUTH
AND WEST HANNA MOVES BEFORE IT BEGINS TO MOVE NORTHWESTWARD. MOST
OF THE MODEL GUIDANCE KEEPS HANNA OVER OR JUST EAST OF THE
BAHAMAS...THE EXCEPTION BEING THE UKMET AND ECMWF MODELS...WHICH
BRING HANNA NEAR THE NORTH-CENTRAL COAST OF CUBA BY DAY 4 AND INTO
THE FLORIDA STRAITS BY DAY 5. AT THIS TIME...THE SPECIFICS OF THOSE
TWO TRACKS ARE CONSIDERED TO BE OUTLIERS...BUT THEY HAVE NOT BEEN
ENTIRELY DISCOUNTED. THE OFFICIAL TRACK IS CLOSE TO THE PREVIOUS
FORECAST TRACK AND THE NHC MODEL CONSENSUS.

THE INTENSITY FORECAST IS SOMEWHAT TRICKY. WITH MORE THAN 30 KT OF
SHEAR FORECAST TO AFFECT HANNA BY 48 HOURS...THE CYCLONE COULD
EASILY BE SHEARED APART. HOWEVER...WHILE THE SHEAR WILL BE
STRONG...ITS NEGATIVE EFFECTS MAY BE OFFSET BY THE STRONG
UPPER-LEVEL DIFLUENT PATTERN THAT IS ALSO FORECAST TO EXIST ACROSS
HANNA AT THAT TIME. BY 72-96 HOURS...ALL OF THE MODELS AGREE ON
ANTICYCLONIC OUTFLOW REPLACING THE STRONG NORTHERLY SHEAR
PATTERN...INCLUDING OUTFLOW JETS DEVELOPING TO THE NORTH AND
SOUTH...WHICH WOULD FAVOR SIGNIFICANT STRENGTHENING OVER 29-30C
SSTS BENEATH THE CYCLONE. HOWEVER...THE INTENSITY FORECAST HAS BEEN
HELD BELOW ALL OF THE AVAILABLE MODEL GUIDANCE DUE TO THE
UNCERTAINTY OF WHAT THE EXACT STRUCTURE OF HANNA WILL BE AFTER THE
UPCOMING STRONG SHEAR PATTERN ABATES IN AROUND 72 HOURS.

FORECAST POSITIONS AND MAX WINDS

INITIAL      31/0900Z 23.2N  69.0W    50 KT
12HR VT     31/1800Z 23.6N  70.2W    50 KT
24HR VT     01/0600Z 23.7N  71.4W    50 KT
36HR VT     01/1800Z 23.7N  72.5W    50 KT
48HR VT     02/0600Z 23.3N  73.1W    50 KT
72HR VT     03/0600Z 23.6N  73.9W    55 KT
96HR VT     04/0600Z 25.1N  75.4W    60 KT
120HR VT     05/0600Z 28.0N  78.0W    70 KT

$$
FORECASTER STEWART



000

WTNT43 KNHC 311446
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT SUN AUG 31 2008

HANNA'S OVERALL SATELLITE APPEARANCE REMAINS RATHER RAGGED AND DEEP
CONVECTION IS LIMITED NEAR THE LOW-LEVEL CIRCULATION.  THE INITIAL
INTENSITY IS LOWERED TO 45 KT BASED ON LATEST SATELLITE INTENSITY
ESTIMATES AND NEARBY BUOY 41046.  HANNA WILL ENCOUNTER A RATHER
COMPLICATED ATMOSPHERIC ENVIRONMENT DURING THE NEXT COUPLE OF DAYS
MAKING THE INTENSITY FORECAST PROBLEMATIC.  WHILE MOST OF THE
DYNAMICAL GUIDANCE SUGGEST THAT THE UPPER-LEVEL LOW CURRENTLY OVER
HANNA WILL GRADUALLY WEAKEN...THEY HAVE NOT NECESSARILY HAD THE
BEST TRACK RECORD FORECASTING THIS FEATURE.  EVEN IF THE UPPER-LOW
DOES WEAKEN AS SHOWN BY THE GLOBAL MODELS...GUSTAV'S OUTFLOW COULD
PRODUCE STRONG NORTHERLY SHEAR OVER HANNA.  INDEED WATER VAPOR
IMAGERY CURRENTLY SHOWS A DEFORMATION AXIS FORMING NORTH OF HANNA
AS A RESULT OF GUSTAV'S OUTFLOW INTERACTING WITH CYCLONIC FLOW
AROUND THE UPPER-LEVEL LOW.   BOTTOM LINE...THE ATMOSPHERE LOOKS
RATHER HOSTILE FOR THE NEXT COUPLE OF DAYS AND SHOULD LIMIT THE
POTENTIAL FOR SIGNIFICANT INTENSIFICATION.  DYNAMICAL MODELS DO
INDICATE SOME IMPROVEMENT IN THE ATMOSPHERIC ENVIRONMENT TOWARD THE
END OF THE FORECAST AS A SECOND UPPER-LEVEL LOW OR CYCLONIC SHEAR
AXIS FORMS TO THE WEST OF HANNA.  HOWEVER...ACCURATELY PREDICTING
THE ENVIRONMENT IN WHICH HANNA WILL BE LOCATED AT DAYS 4 AND 5 IS
DIFFICULT...AND THE NEW OFFICIAL FORECAST IS LITTLE CHANGED FROM
THE PREVIOUS ADVISORY.

HANNA IS CURRENTLY SITUATED SOUTH OF A MID-LEVEL RIDGE OVER THE
WESTERN ATLANTIC RESULTING IN A MOTION TOWARD THE WEST OR 280/09.
GLOBAL MODELS INDICATE THIS RIDGE WILL WEAKEN DURING THE NEXT DAY
OR SO AS A LARGE DEEP-LAYERED TROUGH AMPLIFIES SOUTHWARD OVER THE
WESTERN ATLANTIC.  SUCH AN EVOLUTION IN THE LARGE-SCALE PATTERN IS
EXPECTED TO CAUSE THE STEERING CURRENTS TO COLLAPSE RESULTING IN A
REDUCTION IN HANNA'S FORWARD SPEED AND POSSIBLY SOME ERRATIC
MOTION.  BY DAYS 4 AND 5...THE DEEP-LAYERED TROUGH BEGINS TO LIFT
NORTHEASTWARD AND THE SUBTROPICAL RIDGE BUILDS BACK WESTWARD IN ITS
WAKE.  MOST OF THE TRACK MODELS RESPOND BY TURNING HANNA NORTHWEST
WITH AN INCREASE IN FORWARD SPEED.  HOWEVER...THE UKMET MODEL
ACTUALLY SHOWS THE RIDGE AXIS BUILDING SUFFICIENTLY FAR WEST...AND
TO THE NORTH OF HANNA...TO RESULT IN MORE WESTWARD TRACK.  SINCE
THIS IS A NORMALLY GOOD PERFORMING MODEL...IT CANNOT COMPLETELY BE
IGNORED AND THE NEW OFFICIAL FORECAST LIES SOUTH OF THE DYNAMICAL
MODEL CONSENSUS.

GIVEN THE HIGH SPREAD AMONG THE VARIOUS MODELS...THERE IS
CONSIDERABLE UNCERTAINTY REGARDING HANNA'S EVENTUAL TRACK AND
INTENSITY.

FORECAST POSITIONS AND MAX WINDS

INITIAL      31/1500Z 23.3N  70.0W    45 KT
12HR VT     01/0000Z 23.4N  71.1W    45 KT
24HR VT     01/1200Z 23.5N  72.1W    45 KT
36HR VT     02/0000Z 23.3N  72.9W    50 KT
48HR VT     02/1200Z 23.0N  73.4W    55 KT
72HR VT     03/1200Z 23.5N  74.5W    60 KT
96HR VT     04/1200Z 26.0N  76.0W    65 KT
120HR VT     05/1200Z 29.5N  79.0W    70 KT

$$
FORECASTER RHOME



000

WTNT43 KNHC 312038
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT SUN AUG 31 2008

AN AIR FORCE RECONNAISSANCE AIRCRAFT INVESTIGATING HANNA DURING THE
LAST SEVERAL HOURS FOUND A PEAK FLIGHT LEVEL WIND OF 48 KT WHICH
REDUCES TO APPROXIMATELY 40 KT AT THE SURFACE.  WHILE THERE WERE A
FEW HIGHER VALUES FROM THE SFMR...THESE WERE LIKELY RAIN INFLATED.
THE OVERALL INTENSITY FORECAST REASONING IS ESSENTIALLY UNCHANGED.
HANNA IS CURRENTLY EXPERIENCING STRONG NORTHERLY SHEAR ASSOCIATED
WITH AN UPPER-LEVEL LOW TO ITS SOUTHEAST.  GLOBAL MODELS DO
FORECAST THIS UPPER-LEVEL LOW TO WEAKEN OVER THE NEXT DAY OR SO.
HOWEVER...STRONG NORTHERLY FLOW ASSOCIATED WITH GUSTAV'S
UPPER-LEVEL OUTFLOW SHOULD KEEP NORTHERLY SHEAR OVER HANNA THROUGH
DAY 3.  BY DAYS 4 AND 5...DYNAMICAL MODELS FORECAST A SOMEWHAT
IMPROVED ENVIRONMENT AS A SECOND UPPER-LEVEL LOW OR CYCLONIC SHEAR
AXIS FORMS TO THE WEST OF HANNA.  THIS WOULD PUT HANNA IN A MORE
FAVORABLE ENVIRONMENT FOR STRENGTHENING.  HOWEVER...ACCURATELY
PREDICTING HANNA'S PROXIMITY TO LARGE-SCALE ATMOSPHERIC FEATURES AT
DAYS 4 AND 5 IS DIFFICULT...TO SAY THE LEAST.  GIVEN THE
UNCERTAINTY...THE OFFICIAL FORECAST SHOWS SLOW STRENGTHENING...BUT
IS BELOW THE INTENSITY MODEL CONSENSUS.

HANNA CONTINUES TO BE STEERED BY A MID-LEVEL RIDGE OVER THE WESTERN
ATLANTIC...RESULTING IN A MOTION TOWARD THE WEST OR 280/09. GLOBAL
MODELS INDICATE THIS RIDGE WILL WEAKEN DURING THE NEXT DAY OR SO AS
A LARGE DEEP-LAYER TROUGH AMPLIFIES SOUTHWARD OVER THE WESTERN
ATLANTIC. SUCH AN EVOLUTION IN THE LARGE-SCALE PATTERN SHOULD CAUSE
THE STEERING CURRENTS TO COLLAPSE RESULTING IN A DECREASE IN
HANNA'S FORWARD SPEED. IN FACT...SOME OF THE MODELS SHOW HANNA
MEANDERING OVER OR JUST NORTHEAST OF THE CENTRAL BAHAMAS. BY DAY
3...THE DEEP-LAYER TROUGH IS FORECAST TO LIFT NORTHEASTWARD
ALLOWING THE SUBTROPICAL RIDGE TO BUILD BACK WESTWARD IN ITS WAKE.
THERE REMAINS CONSIDERABLE SPREAD AMONG THE DYNAMICAL MODELS AT THE
EXTENDED RANGE. THE GFS...GFDL...AND THE HWRF MODELS LIE ALONG THE
RIGHT SIDE OF THE MODEL ENVELOPE AND SHOW HANNA LIFTING QUICKLY
NORTHWESTWARD AROUND THE WESTERN PERIPHERY OF THE RIDGE.
CONVERSELY...THE UKMET MODEL SHOWS THE RIDGE NOSING WESTWARD TO THE
NORTH OF HANNA...PRODUCING A TRACK ALONG THE LEFT...OR
SOUTHWEST...SIDE OF THE MODEL ENVELOPE. SINCE THERE IS NO CLEAR
REASON TO FAVOR ONE SCENARIO OVER THE OTHER AT THIS TIME...I'VE
ELECTED TO LEAVE THE OFFICIAL FORECAST ESSENTIALLY UNCHANGED BEYOND
72 HOURS.

FORECAST POSITIONS AND MAX WINDS

INITIAL      31/2100Z 23.5N  71.4W    40 KT
12HR VT     01/0600Z 23.5N  72.3W    40 KT
24HR VT     01/1800Z 23.3N  73.1W    45 KT
36HR VT     02/0600Z 23.3N  73.7W    50 KT
48HR VT     02/1800Z 23.5N  74.1W    55 KT
72HR VT     03/1800Z 24.5N  75.0W    60 KT
96HR VT     04/1800Z 27.5N  77.5W    65 KT
120HR VT     05/1800Z 31.5N  81.0W    65 KT

$$
FORECASTER RHOME



000

WTNT43 KNHC 010258
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT SUN AUG 31 2008

SINCE THE RECONNAISSANCE AIRCRAFT DEPARTED HANNA THIS AFTERNOON...
DEEP CONVECTION HAS BECOME A LITTLE MORE CONCENTRATED JUST
SOUTHEAST OF THE CENTER. SEVERAL MICROWAVE IMAGES FROM BETWEEN 2200
AND 0000 UTC HAVE BEEN VERY HELPFUL IN LOCATING THE CENTER. DVORAK
INTENSITY ESTIMATES HAVE INCREASED AGAIN TO T3.0 OR 45 KT... AND
NOAA BUOY 41046 RECENTLY REPORTED A PEAK ONE-MINUTE WIND SPEED OF
39 KT VERY NEAR THE AREA OF DEEP CONVECTION. THESE DATA SUPPORT
INCREASING THE INTENSITY TO 45 KT.

BOTH THE SHIPS MODEL AND UW-CIMSS DIAGNOSE ABOUT 20 KT OF
NORTHWESTERLY SHEAR OVER HANNA AT THIS TIME. THE SHIPS GUIDANCE AND
THE GLOBAL MODELS PREDICT SIMILAR OR SLIGHTLY HIGHER SHEAR VALUES
DURING THE NEXT 2-3 DAYS. GIVEN THIS SHEAR...IT IS TEMPTING TO NOT
FORECAST ANY STRENGTHENING DURING THIS TIME...BUT MOST OF THE
GUIDANCE SHOWS SOME INTENSIFICATION. LATE IN THE FORECAST
PERIOD...THERE ARE SOME INDICATIONS THAT THE UPPER-LEVEL
ENVIRONMENT COULD BECOME SOMEWHAT MORE CONDUCIVE FOR
STRENGTHENING...HOWEVER IT WILL DEPEND ON EXACTLY WHERE HANNA IS
LOCATED. THE LGEM MODEL IS AT THE LOW END OF THE SPECTRUM AND
FORECASTS VERY LITTLE INTENSITY CHANGE DURING THE NEXT 5 DAYS. THE
NEW INTENSITY FORECAST IS VERY SIMILAR TO PREVIOUS ADVISORY THROUGH
36 HOURS...BUT IS A LITTLE MORE CONSERVATIVE THEREAFTER AND USES A
BLEND OF THE SHIPS AND LGEM MODELS AT 3 DAYS AND BEYOND.

HANNA HAS BEEN MOVING WESTWARD OR 280/7 KT. THE BUILDING DEEP-LAYER
RIDGE OVER THE EASTERN UNITED STATES IS FORECAST TO BLOCK HANNA'S
FORWARD MOTION VERY SOON...AND THE TRACK GUIDANCE SHOWS VERY SLOW
AND ERRATIC MOTION OVER THE NEXT COUPLE OF DAYS. AFTER 48
HOURS...THE RIDGE BEGINS TO WEAKEN OVER THE U.S. WHILE ANOTHER
RIDGE BUILDS OVER THE ATLANTIC TO THE NORTHEAST OF HANNA. THE
ATLANTIC RIDGE IS EXPECTED TO STEER THE STORM NORTHWESTWARD BY THAT
TIME. THE TRACK GUIDANCE GENERALLY AGREES ON THIS SCENARIO...BUT
THE SPREAD OF THE GUIDANCE REMAINS QUITE LARGE AT DAYS 4 AND 5. THE
UKMET REMAINS THE SOUTHERN OUTLIER WITH A TRACK NEAR CUBA AND
SOUTHERN FLORIDA...WHILE THE GFS...HWRF...AND GFDL ARE ON THE
EASTERN EDGE OF THE GUIDANCE ENVELOPE WITH A TRACK TOWARDS THE
CAROLINAS. THE OFFICIAL FORECAST REMAINS VERY CLOSE TO THE PREVIOUS
ADVISORY AND CLOSE TO THE MODEL CONSENSUS WHICH HAS SHIFTED EVER SO
SLIGHTLY WESTWARD.


FORECAST POSITIONS AND MAX WINDS

INITIAL      01/0300Z 23.7N  72.2W    45 KT
12HR VT     01/1200Z 23.5N  72.9W    45 KT
24HR VT     02/0000Z 23.4N  73.5W    45 KT
36HR VT     02/1200Z 23.4N  73.7W    50 KT
48HR VT     03/0000Z 23.7N  74.2W    50 KT
72HR VT     04/0000Z 25.4N  75.8W    55 KT
96HR VT     05/0000Z 29.0N  79.0W    60 KT
120HR VT     06/0000Z 33.5N  82.0W    45 KT...INLAND

$$
FORECASTER BROWN




WTNT43 KNHC 010848
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT MON SEP 01 2008

DURING THE PAST 6 HOURS...A LARGE MASS OF INTENSE CONVECTION WITH
CLOUD TOP TEMPERATURES AS COLD AS -87C HAS DEVELOPED IN THE
SOUTHEASTERN SEMICIRCLE OF HANNA. NOAA BUOY 41046 JUST EAST OF THE
ALLEGED CENTER HAS REPORTED 1-MINUTE SUSTAINED WINDS OF 43 KT...
WHICH EASILY SUPPORTS AN INITIAL INTENSITY OF 45 KT...AND HANNA
COULD EVEN BE A LITTLE STRONGER BASED ON AN EARLIER PRESSURE OF
997.1 MB FROM THE SAME BUOY. A RECON AIRCRAFT WILL INVESTIGATE
HANNA LATER TODAY AND PROVIDE A BETTER ESTIMATE OF INTENSITY.

THE INITIAL MOTION IS AN UNCERTAIN 260/02...DUE MAINLY TO SOME
UNCERTAINTY IN THE EXACT LOCATION OF THE CENTER. A 01/0224Z ASCAT
OVERPASS SUGGESTED THE CENTER OF HANNA WAS FARTHER SOUTHEAST AND
EMBEDDED IN THE DEEP CONVECTION. IF THAT IS THE CASE...HANNA WOULD
EASILY BE A 55-KT OR STRONGER TROPICAL STORM. HOWEVER...EARLIER
PASSIVE MICROWAVE IMAGERY...THE MOST RECENT NIGHTTIME VISIBLE
IMAGERY...AND THE CURRENT NORTHWESTERLY SHEAR PATTERN ALL SUGGEST
THAT THE CENTER SHOULD BE LOCATED NEAR THE NORTHWESTERN EDGE OF THE
DEEP CONVECTION RATHER THAN EMBEDDED WITHIN IT. IN CONTRAST TO THE
UNCERTAINTY ASSOCIATED WITH THE LOCATION OF HANNA...ALL OF THE
GLOBAL MODELS HAVE NEARLY IDENTICAL FORECAST SCENARIOS OF THE MID-
TO UPPER-LEVEL FLOW PATTERNS. THE BERMUDA HIGH IS FORECAST TO
EXTEND WESTWARD ACROSS THE ATLANTIC AND INTO THE TENNESSEE VALLEY
BY DAYS 3-5...WHILE AN UPPER-LEVEL TROUGH DIGS SOUTHWARD OFF THE
U.S. EAST COAST AND SPLITS...WITH THE SOUTHERN PORTION DIGGING
SOUTH OF HANNA AND THE NORTHERN PORTION LIFTING OUT AND ALLOWING
RIDGING TO FILL IN BEHIND THE TROUGH TO THE NORTH OF HANNA. THIS
COMBINED FLOW PATTERN IS EXPECTED TO ACCELERATE HANNA TOWARD THE
SOUTHEASTERN U.S. COAST BY 72-96 HOURS/DAYS 3-4. THE PRIMARY
DIFFERENCE IN THE MODELS IS HOW THEY HANDLE THE SIZE OF HANNA
BETWEEN NOW AND 72 HOURS. THE ECMWF AND UKMET KEEP HANNA ABOUT 100
NMI IN DIAMETER SMALLER AT 500 MB THAN THE OTHER MODELS DO...WHICH
RESULTS IN MORE RIDGING TO EXIST ON THE EAST SIDE OF HANNA...AND
WHICH FORCES THE CYCLONE CLOSER TO THE FLORIDA EAST COAST. THE
OFFICIAL FORECAST TRACK IS ALMOST IDENTICAL TO THE PREVIOUS TRACK
AND IS VERY CLOSE TO THE MODEL CONSENSUS AND LEANS A LITTLE TOWARD
THE ECMWF-UKMET SCENARIOS BASED ON HANNA'S CURRENT SIZE.

LITTLE...IF ANY...STRENGTHENING IS EXPECTED DURING THE NEXT 48 HOURS
DUE TO HOSTILE NORTHERLY SHEAR CONDITIONS. HOWEVER...BY 96 HOURS...
ALL OF THE MODELS HAVE ALMOST IDENTICAL 200 MB FLOW PATTERNS
INDICATING THE DEVELOPMENT OF BOTH POLEWARD AND EQUATORWARD OUTFLOW
REGIMES SURROUNDING HANNA. THIS TYPE OF DUAL JET PATTERN WOULD
FAVOR SIGNIFICANT INTENSIFICATION...AND HANNA COULD EASILY BE A
HURRICANE BEFORE IT MAKES LANDFALL ALONG THE SOUTHEASTERN U.S.
COAST. THE OFFICIAL INTENSITY IS SIMILAR TO THE SHIPS MODEL...BUT
REMAINS BELOW ALL OF THE AVAILABLE NHC INTENSITY GUIDANCE.

ALL INTERESTS IN FLORIDA SHOULD CLOSELY MONITOR THE FORECASTS FOR
HANNA SINCE ONLY A SLIGHT DEVIATION TO THE WEST OF THE OFFICIAL
TRACK COULD BRING THE CENTER OF HANNA MUCH CLOSER TO THE FLORIDA
EAST COAST AND THE BAHAMAS THAN CURRENTLY INDICATED.

FORECAST POSITIONS AND MAX WINDS

INITIAL      01/0900Z 23.6N  72.4W    45 KT
12HR VT     01/1800Z 23.4N  73.0W    50 KT
24HR VT     02/0600Z 23.4N  73.5W    50 KT
36HR VT     02/1800Z 23.7N  74.0W    50 KT
48HR VT     03/0600Z 24.2N  74.5W    55 KT
72HR VT     04/0600Z 26.2N  76.5W    60 KT
96HR VT     05/0600Z 30.0N  80.0W    65 KT
120HR VT     06/0600Z 35.0N  82.5W    30 KT...INLAND

$$
FORECASTER STEWART




WTNT43 KNHC 011452
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT MON SEP 01 2008

HANNA'S OVERALL SATELLITE PRESENTATION HAS BEEN IMPROVING THIS
MORNING WITH AN IMPRESSIVE CDO FEATURE NOW COVERING THE LOW-LEVEL
CIRCULATION.  DVORAK SATELLITE INTENSITY ESTIMATES HAVE INCREASED
AND SUGGEST MAX WINDS NEAR 55 KT.  I'M GOING TO CONSERVATIVELY SET
THE INITIAL INTENSITY TO 50 KT SINCE AN AIR FORCE RECONNAISSANCE
AIRCRAFT IS ON ITS WAY.  HAVING SAID THAT...A RECENT QUIKSCAT PASS
SUGGEST THAT THE LOW-LEVEL CIRCULATION COULD BE LOCATED A LITTLE
FARTHER INTO THE DEEP CONVECTION.  THIS SUGGEST THAT HANNA COULD BE
STRONGER THAN ESTIMATED.   THE INTENSITY FORECAST REMAINS TRICKY.
WATER VAPOR IMAGERY SUGGESTS THAT THE UPPER-LEVEL LOW WHICH HAD
PREVIOUSLY INHIBITED DEVELOPMENT HAS DISSIPATED...AND HANNA NOW
FINDS ITSELF IN A VERY SMALL AREA OF LOW SHEAR.  HOWEVER...WATER
VAPOR IMAGERY ALSO SHOWS STRONG NORTHERLY FLOW ASSOCIATED WITH
GUSTAV'S UPPER-LEVEL OUTFLOW JUST NORTH OF HANNA...AND GLOBAL MODELS
FORECAST MODERATE TO STRONG NORTHERLY SHEAR PERSISTING DURING THE
NEXT DAY OR SO.  GIVEN THE UNCERTAINTY...THE OFFICIAL INTENSITY
FORECAST IS CLOSE TO THE MODEL CONSENSUS AND SHOWS HANNA BECOMING A
HURRICANE A LITTLE SOONER THAN THE PREVIOUS ADVISORY.  BY 72
HOURS...GLOBAL MODELS SUGGEST THE SHEAR COULD WEAKEN...AND HANNA
COULD FIND ITSELF IN A MORE FAVORABLE ENVIRONMENT FOR
STRENGTHENING.  STILL...PREDICTING THE ATMOSPHERIC ENVIRONMENT...
AND TROPICAL CYCLONE INTENSITY...AT DAYS 3-5 IS VERY DIFFICULT.

WHILE THE CENTER IS DIFFICULT TO LOCATE...HANNA APPEARS TO BE MOVING
MORE TOWARD THE WEST-SOUTHWEST OR 250/4.  A VERY SLOW WEST-
SOUTHWEST OR SOUTHWEST MOTION IS EXPECTED DURING THE NEXT 36 HOURS.
IN 2 TO 3 DAYS...THE SUBTROPICAL RIDGE IS EXPECTED TO BUILD
WESTWARD OVER THE CENTRAL ATLANTIC CAUSING HANNA TO MOVE
NORTHWESTWARD WITH AN INCREASE IN FORWARD SPEED. THE NEW OFFICIAL
TRACK FORECAST IS ADJUSTED A LITTLE TO THE SOUTH THROUGH 36 HOURS
BASED ON THE LATEST MOTION. TRACK GUIDANCE HAS NOT CHANGED
SIGNIFICANTLY AT THE EXTENDED RANGES AND NEITHER HAS THE OFFICIAL
FORECAST.

FORECAST POSITIONS AND MAX WINDS

INITIAL      01/1500Z 23.0N  72.9W    50 KT
12HR VT     02/0000Z 22.8N  73.3W    55 KT
24HR VT     02/1200Z 22.7N  73.7W    55 KT
36HR VT     03/0000Z 22.9N  74.1W    60 KT
48HR VT     03/1200Z 23.7N  74.9W    65 KT
72HR VT     04/1200Z 26.5N  77.5W    70 KT
96HR VT     05/1200Z 30.5N  80.5W    70 KT
120HR VT     06/1200Z 36.5N  82.0W    35 KT...INLAND

$$
FORECASTER RHOME/AVILA



000

WTNT43 KNHC 011732
TCDAT3
HURRICANE HANNA SPECIAL DISCUSSION NUMBER  19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
130 PM EDT MON SEP 01 2008

THIS SPECIAL ADVISORY IS TO UPDATE THE INTENSITY OF HANNA.  DATA
FROM THE AIR FORCE RECONNAISSANCE AIRCRAFT INDICATE THAT HANNA IS
NOW A HURRICANE WITH 65 KT WINDS.  THE INTENSITY HAS BEEN ADJUSTED
UPWARD AT ALL FORECAST TIMES.  THE TRACK HAS ALSO BEEN SLIGHTLY
ADJUSTED BASED ON THE LATEST FIX.  THIS SPECIAL ADVISORY SUPERSEDES
THE INTERMEDIATE ADVISORY.


FORECAST POSITIONS AND MAX WINDS

INITIAL      01/1730Z 22.4N  72.6W    65 KT
12HR VT     02/0000Z 22.4N  73.3W    70 KT
24HR VT     02/1200Z 22.5N  73.7W    70 KT
36HR VT     03/0000Z 22.8N  74.2W    70 KT
48HR VT     03/1200Z 23.7N  74.9W    75 KT
72HR VT     04/1200Z 26.5N  77.5W    80 KT
96HR VT     05/1200Z 30.5N  80.5W    80 KT
120HR VT     06/1200Z 36.5N  82.0W    30 KT...INLAND

$$
FORECASTER RHOME/AVILA




WTNT43 KNHC 012050
TCDAT3
HURRICANE HANNA DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT MON SEP 01 2008

THE AIR FORCE RECONNAISSANCE AIRCRAFT RECENTLY FOUND A CENTRAL
PRESSURE OF 983 MB AND A PEAK FLIGHT LEVEL WIND OF 89 KT.  THESE
NUMBERS INDICATE HANNA HAS CONTINUED TO STRENGTHEN IN THE FACE OF
WHAT APPEARS TO BE STRONG NORTHERLY SHEAR...AND THE INITIAL
INTENSITY IS INCREASED TO 70 KT.  THE INTENSITY FORECAST REMAINS
DIFFICULT SINCE GLOBAL MODES SHOW THE SHEAR REMAINING STRONG OR
POSSIBLY INCREASING DURING THE NEXT COUPLE OF DAYS.  GIVEN HANNA'S
TENACITY THUS FAR...THE OFFICIAL FORECAST PRESUMES THAT HANNA WILL
BE ABLE TO FIGHT OFF THE SHEAR.  AT DAY 5...HANNA IS FORECAST TO BE
INLAND SO WEAKENING IS SHOWN.

THE LAST FEW FIXES FROM THE AIRCRAFT INDICATE THAT HANNA HAS BEEN
MEANDERING.  HOWEVER...A 12-HOUR AVERAGE MOTION IS SOUTH-
SOUTHWESTWARD AT ABOUT 4 KT AND THIS WILL BE THE INITIAL MOTION
ESTIMATE.  WITH THE SUBTROPICAL RIDGE NORTH OF HANNA NOW
DISSIPATED...THE CYCLONE'S MOTION DURING THE NEXT COUPLE OF DAYS IS
EXPECTED TO BE SLOW AND POSSIBLY ERRATIC.   AFTER THAT...GLOBAL
MODELS SHOW THE SUBTROPICAL RIDGE BUILDING BACK OVER THE
WEST-CENTRAL ATLANTIC...AND THIS SHOULD CAUSE HANNA TO TURN
NORTHWEST WITH AN INCREASE IN FORWARD SPEED.  THERE IS STILL SOME
SPREAD AMONG THE VARIOUS TRACK MODELS WITH POTENTIAL AREAS OF
IMPACT RANGING FROM SOUTH FLORIDA THROUGH THE CAROLINAS.  UNTIL
HANNA TAKES A MORE DEFINITIVE MOTION...IT WILL BE DIFFICULT TO BE
MORE SPECIFIC ABOUT THE POTENTIAL THREAT AREA.  ALL INTERESTS ALONG
THE SOUTHEASTERN UNITED STATES COASTS SHOULD MONITOR THE PROGRESS
OF THIS SYSTEM.

FORECAST POSITIONS AND MAX WINDS

INITIAL      01/2100Z 22.2N  72.6W    70 KT
12HR VT     02/0600Z 21.9N  72.9W    75 KT
24HR VT     02/1800Z 21.8N  73.5W    75 KT
36HR VT     03/0600Z 22.1N  73.9W    75 KT
48HR VT     03/1800Z 23.1N  74.5W    75 KT
72HR VT     04/1800Z 27.0N  78.0W    85 KT
96HR VT     05/1800Z 31.5N  81.0W    85 KT
120HR VT     06/1800Z 39.0N  80.5W    25 KT...INLAND

$$
FORECASTER RHOME/AVILA



000

WTNT43 KNHC 020257
TCDAT3
HURRICANE HANNA DISCUSSION NUMBER  21
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT MON SEP 01 2008

WHILE THE AREAL COVERAGE OF DEEP CONVECTION HAS DECREASED OVER THE
PAST COUPLE OF HOURS...WHAT'S LEFT SHOWS GOOD BANDING IN AGREEMENT
WITH RECENT MICROWAVE IMAGERY.  THE PINE CAY SURFACE STATION IN THE
CAICOS ISLAND SUGGESTS THAT THE PRESSURE HAS FALLEN TO ABOUT 978
MB.  THE NORTHERLY FLOW ALOFT...ASSOCIATED WITH THE OUTFLOW FROM
GUSTAV...IS CLEARLY NOT MAKING IT INTO THE CENTER OF THE TROPICAL
CYCLONE.  EVEN SO...ONLY MODEST CHANGES IN INTENSITY ARE
ANTICIPATED OVER THE NEXT 24-36 HOURS UNTIL THE UPPER FLOW BEGINS
TO REVERSE WHEN MID- TO UPPER-LEVEL RIDGING BUILDS IN OVER THE
WESTERN ATLANTIC.  THERE IS GOOD AGREEMENT AMONG THE GLOBAL MODELS
ON THIS EVOLUTION...WHICH SHOULD CREATE A MORE FAVORABLE PATTERN
FOR INTENSIFICATION.  THE OFFICIAL INTENSITY FORECAST LIES A LITTLE
ABOVE THE PREVIOUS ONE...AND IS CLOSE TO A BLEND OF THE
GFDL/HWRF/SHIPS/LGEM GUIDANCE...WITH THE DYNAMICAL MODELS A LITTLE
HIGHER AND THE STATISTICAL MODELS A LITTLE LOWER.  ONE SHOULD NOT
INTERPOLATE A PRESUMED LANDFALL INTENSITY FROM THE 72 AND 96 HOUR
FORECAST POINTS...AS SOME ADDITIONAL STRENGTHENING COULD OCCUR
BETWEEN 72 HOURS AND LANDFALL.

THERE HAS BEEN NO AIRCRAFT RECONNAISSANCE THIS EVENING AND PRECISE
LOCATION OF THE CENTER IS DIFFICULT.  IT APPEARS THAT THE CENTER
HAS BEEN MEANDERING...FIRST APPROACHING THE STATION AT PINE CAY BUT
IN RECENT HOURS MOVING AWAY AS THE WINDS AT THAT STATION HAVE
INCREASED TO 58 MPH IN THE LAST HOUR.  WITH NO DEFINITIVE TREND YET
ESTABLISHED...THE INITIAL MOTION IS ESTIMATED TO BE STATIONARY.
HANNA IS CURRENTLY BLOCKED BY HIGH PRESSURE EXTENDING SOUTHWARD
FROM THE GREAT LAKES...BUT THIS FEATURE IS FORECAST BY THE GLOBAL
MODELS TO WEAKEN AND SHIFT EASTWARD.  AS HIGH PRESSURE DEVELOPS
OVER THE WESTERN ATLANTIC OVER THE NEXT 2 TO 3 DAYS...A
NORTHWESTWARD TRACK FOR HANNA IS EXPECTED TO DEVELOP.  WITH THE
EXCEPTION OF THE UKMET...THE MODEL GUIDANCE IS REMARKABLY WELL
CLUSTERED.  THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY TO THE EAST
OF THE PREVIOUS ADVISORY AND IS ONLY SLIGHTLY TO THE LEFT OF THE
GFS...GFDL...AND HWRF.  THE UKMET STILL IS THE LEFT-MOST
OUTLIER...SHOWING MORE OF A SOUTHWESTWARD MOTION INITIALLY AND A
TRACK CLOSER TO THE FLORIDA PENINSULA...ALTHOUGH IT IS WORTH NOTING
THAT THE 18Z UKMET SHOWS LESS OF THIS INITIAL SOUTHWESTWARD JUMP
THAN THE FULL RUN FROM 12Z.


FORECAST POSITIONS AND MAX WINDS

INITIAL      02/0300Z 21.8N  72.5W    70 KT
12HR VT     02/1200Z 21.8N  72.8W    75 KT
24HR VT     03/0000Z 22.0N  73.3W    75 KT
36HR VT     03/1200Z 22.8N  74.0W    80 KT
48HR VT     04/0000Z 24.0N  75.0W    85 KT
72HR VT     05/0000Z 28.0N  78.0W    90 KT
96HR VT     06/0000Z 34.0N  80.5W    65 KT...INLAND
120HR VT     07/0000Z 41.5N  77.0W    30 KT...REMNANT LOW

$$
FORECASTER FRANKLIN




WTNT43 KNHC 020859
TCDAT3
HURRICANE HANNA DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT TUE SEP 02 2008

CONVENTIONAL AND PASSIVE MICROWAVE SATELLITE IMAGERY INDICATE HANNA
HAS MOVED SOUTHWARD OVER THE PAST 6 HOURS WHILE MAINTAINING A
PRONOUNCED EYE FEATURE IN A 02/203Z AMSU OVERPASS. SATELLITE
INTENSITY ESTIMATES ARE T4.0/65 KT AND T4.5/77 KT FROM TAFB AND
SAB...RESPECTIVELY. THEREFORE...THE INITIAL INTENSITY REMAINS
UNCHANGED AT 70 KT FOR THIS ADVISORY.

THE INITIAL MOTION ESTIMATE IS AN UNCERTAIN 270/02 KT. LATEST
SATELLITE POSITION ESTIMATES SUGGEST THAT HANNA COULD STILL BE
MOVING SOUTHWARD. HOWEVER...ALL OF THE GLOBAL MODELS ARE NOW IN
EXCELLENT AGREEMENT THAT AN UPPER-LEVEL LOW WILL PINCH OFF TO THE
SOUTH AND WEST OF HANNA DURING THE NEXT 24-36 HOURS...WHICH  IS
EXPECTED TO INDUCE A SLOW NORTH AND THEN NORTHWESTWARD MOTION
ACROSS THE SOUTHEASTERN BAHAMAS. BY 48-72 HOURS...THE SUBTROPICAL
RIDGE TO THE NORTHEAST OF HANNA IS FORECAST TO GRADUALLY BUILD
WESTWARD THROUGH 96 HOURS...WHICH SHOULD INDUCE A FASTER FORWARD
NORTHWESTWARD MOTION TOWARD THE SOUTHEASTERN UNITED STATES. THE
RIDGE AXIS IS FORECAST BY ALL THE MODELS TO GENERALLY EXTEND
EAST-WEST BETWEEN 32-24N LATITUDE...AND THE EXACT TRACK OF HANNA
WILL DEPEND HEAVILY ON HOW FAR SOUTH AND WEST THE CYCLONE MOVES
DURING THE NEXT 36 HOURS...AND ALSO HOW STRONG THE WESTERN PORTION
OF THE RIDGE WILL BE. THE OFFICIAL FORECAST TRACK IS CLOSE TO THE
PREVIOUS ADVISORY AND IS DOWN THE MIDDLE OF THE TIGHTLY CLUSTERED
NHC MODEL GUIDANCE SUITE. HANNA IS FORECAST TO MOVE NORTHWESTWARD
UNTIL IT REACHES THE COAST OF SOUTH CAROLINA...AFTER WHICH IT IS
EXPECTED TO GRADUALLY RECURVE TO THE NORTHEAST. AN APPROXIMATE
84-HOUR POSITION WOULD BE NEAR 31.3N 80.2W.

HANNA HAS MAINTAINED A WELL-DEFINED INNER-CORE STRUCTURE BASED ON
THE 0202Z AMSU OVERPASS...AND ANOTHER CDO FEATURE WITH CLOUD TOPS
AS COLD OF -80C TO -87C HAS REDEVELOPED OVER THE CENTER SIMILAR TO
THE THIS TIME LAST NIGHT. THE CURRENT 30-KT NORTHERLY SHEAR PATTERN
IS FORECAST BY ALL THE MODELS TO BEGIN TO WEAKEN TODAY AND CONTINUE
TO WEAKEN DURING THE NEXT 48 HOURS...AND GRADUALLY SWITCH TO A
SOUTHEASTERLY COMPONENT WITH LESS THAN 15 KT OF SHEAR AT 72-96
HOURS. GIVEN THE DEVELOPMENT OF A FAVORABLE UPPER-LEVEL OUTFLOW
PATTERN AND SSTS OF AT LEAST 28C ALONG THE FORECAST TRACK UNTIL
LANDFALL...STEADY INTENSIFICATION SEEMS QUITE REASONABLE. THE
OFFICIAL INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY
...AND IS SIMILAR TO THE SHIPS MODEL. IT IS IMPORTANT TO NOTE THAT
HANNA IS EXPECTED TO CONTINUE TO INTENSIFY...OR AT LEAST REMAIN
STEADY...UNTIL LANDFALL OCCURS BETWEEN 84 AND 96 HOURS...RATHER
THAN APPEAR TO BE WEAKENING LIKE SOME AUTOMATIC INTENSITY PLOTTING
SOFTWARE MAY SHOW. IN FACT...BY 84 HOURS HANNA COULD BE A MAJOR
HURRICANE.

FORECAST POSITIONS AND MAX WINDS

INITIAL      02/0900Z 21.3N  72.7W    70 KT
12HR VT     02/1800Z 21.4N  73.1W    70 KT
24HR VT     03/0600Z 22.0N  73.5W    75 KT
36HR VT     03/1800Z 23.0N  74.3W    80 KT
48HR VT     04/0600Z 24.4N  75.5W    85 KT
72HR VT     05/0600Z 28.7N  79.0W    90 KT
96HR VT     06/0600Z 34.7N  80.7W    55 KT...INLAND
120HR VT     07/0600Z 42.5N  74.0W    35 KT...EXTRATROPICAL INLAND

$$
FORECASTER STEWART




WTNT43 KNHC 021455
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT TUE SEP 02 2008

HANNA HAS FINALLY SUCCUMBED TO THE STRONG VERTICAL SHEAR WITH
VISIBLE SATELLITE IMAGERY SHOWING A PARTIALLY EXPOSED LOW-LEVEL
CIRCULATION AND A SHRINKING CDO FEATURE.  THE INITIAL INTENSITY IS
SET AT 60 KT...BUT GIVEN THE CURRENT SATELLITE PRESENTATION...THIS
MIGHT BE A BIT GENEROUS.  AN AIR FORCE RECONNAISSANCE AIRCRAFT WILL
INVESTIGATE HANNA THIS AFTERNOON AND PROVIDE A BETTER INTENSITY
ESTIMATE.  WATER VAPOR IMAGERY SHOWS A SHARP EDGE OR DEFORMATION
AXIS ON THE NORTH SIDE OF THE CIRRUS CANOPY SUGGESTING THAT THE
SHEAR WILL PERSIST IN THE SHORT-TERM...AND SOME ADDITIONAL
WEAKENING IS POSSIBLE TODAY AND TONIGHT.  IN ABOUT 24
HOURS...GLOBAL MODELS SHOW THE SHEAR WEAKENING AND THIS COULD ALLOW
HANNA TO RESTRENGTHEN.  HOWEVER...GIVEN THE PRESENT LACK OF
ORGANIZATION...IT IS DIFFICULT TO KNOW HOW MUCH STRENGTHENING IS
POSSIBLE.  THE NEW OFFICIAL FORECAST IS LOWER THAN THE PREVIOUS
ADVISORY BUT SHOWS HANNA BECOMING A CATEGORY ONE HURRICANE IN ABOUT
36 HOURS.  IT SHOULD BE NOTED THAT THIS IS A LOW CONFIDENCE
FORECAST.  IN FACT...IF ONE CONSULTS THE WIND SPEED PROBABILITY
PRODUCT INCLUDED IN THIS PACKAGE...IT CAN BE SEEN THAT THERE IS
NEARLY AN EQUAL PROBABILITY OF HANNA BEING A TROPICAL STORM OR
HURRICANE AT DAY 3.

HANNA CONTINUES TO MEANDER BUT THE BEST ESTIMATE OF AN INITIAL
MOTION IS 250/05. SLOW AND ERRATIC MOTION IS EXPECTED TODAY BUT
HANNA SHOULD START MOVING NORTHWESTWARD TONIGHT OR TOMORROW AS A
LARGE MID-LATITUDE TROUGH OVER THE WESTERN ATLANTIC LIFTS NORTHWARD
AND THE SUBTROPICAL RIDGE BUILDS BACK IN. HANNA SHOULD ACCELERATE
NORTHWESTWARD AT DAYS 2 TO 3 AS THE RIDGE STRENGTHENS. DYNAMICAL
TRACK MODELS HAVE SHIFTED A LITTLE TO THE WEST AND THE NEW OFFICIAL
FORECAST FOLLOWS SUIT. ON THE FORECAST TRACK...HANNA IS EXPECTED TO
APPROACH THE EAST COAST OF FLORIDA... GEORGIA...OR SOUTH CAROLINA
IN 2 TO 3 DAYS. IT SHOULD BE STRESSED THAT THE EXPECTED ANGLE OF
APPROACH AND TRACK UNCERTAINTY MAKE IT IMPOSSIBLE TO NARROW DOWN
THE POTENTIAL IMPACT AREA. INTERESTS IN THE NORTHWESTERN BAHAMAS
AND ALONG THE ENTIRE SOUTHEASTERN UNITED STATES COAST SHOULD
CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM.

FORECAST POSITIONS AND MAX WINDS

INITIAL      02/1500Z 21.0N  73.5W    60 KT
12HR VT     03/0000Z 21.4N  73.7W    55 KT
24HR VT     03/1200Z 22.3N  74.2W    60 KT
36HR VT     04/0000Z 23.6N  75.3W    65 KT
48HR VT     04/1200Z 25.1N  76.8W    70 KT
72HR VT     05/1200Z 29.5N  80.5W    75 KT
96HR VT     06/1200Z 36.5N  80.0W    35 KT...INLAND
120HR VT     07/1200Z 45.5N  70.0W    25 KT...INLAND REMNANT LOW

$$
FORECASTER RHOME/KNABB



000

WTNT43 KNHC 022056
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT TUE SEP 02 2008

AN AIR FORCE RECONNAISSANCE AIRCRAFT CURRENTLY INVESTIGATING HANNA
CONFIRMS THAT THE SYSTEM HAS WEAKENED. THE PEAK FLIGHT-LEVEL WIND
AT 850 MB WAS 66 KT WHICH CORRESPONDS TO ABOUT 55 KT AT THE
SURFACE. HANNA WILL CONTINUE TO ENCOUNTER STRONG SHEAR FOR ANOTHER
12-24 HOURS WHICH SHOULD LIMIT STRENGTHENING IN THE SHORT TERM. BY
TOMORROW...GLOBAL MODELS FORECAST AN UPPER-LEVEL LOW TO CUT OFF
JUST WEST OF HANNA AND THEN DROP SOUTHWARD DURING THE NEXT FEW
DAYS.  IF THIS EVOLUTION MATERIALIZES...AND ASSUMING HANNA IS ABLE
TO FIGHT OFF THE SHEAR...THE ENVIRONMENT WOULD GRADUALLY BECOME
MORE FAVORABLE FOR STRENGTHENING.  THE OFFICIAL INTENSITY FORECAST
CALLS FOR HANNA TO REGAIN HURRICANE STRENGTH IN A DAY OR SO...IN
LINE WITH NEARLY ALL OF THE AVAILABLE INTENSITY MODELS.
HOWEVER...THE EVOLUTION OF THE LARGE-SCALE ENVIRONMENT OVER THE
NEXT DAY OR SO IS COMPLEX...WHICH RESULTS IN LOWER THAN NORMAL
CONFIDENCE IN THE INTENSITY FORECAST.

THE LAST FEW AIRCRAFT FIXES INDICATE THAT HANNA CONTINUES TO DRIFT
SOUTHEASTWARD WITH AN INITIAL MOTION ESTIMATE OF 150/02. TRACK
MODELS INSIST THAT HANNA WILL START ITS MUCH-ANTICIPATED TURN
TOWARD THE NORTHWEST SOON...AS A LARGE MID-LATITUDE TROUGH OVER THE
WESTERN ATLANTIC LIFTS NORTHWARD AND THE SUBTROPICAL RIDGE BUILDS
BACK IN.  SUCH A TRACK WOULD TAKE THE CYCLONE NORTHWESTWARD THROUGH
THE CENTRAL AND NORTHWESTERN BAHAMAS DURING THE NEXT TWO DAYS.
HANNA IS THEN EXPECTED TO ACCELERATE AS IT MAKES ITS APPROACH TO
THE SOUTHEASTERN UNITED STATES.  HOWEVER...UNTIL HANNA BEGINS A
MORE DEFINITIVE MOTION...IT WILL BE DIFFICULT TO NARROW THE
POTENTIAL IMPACT AREA.  IN ADDITION...THE ANTICIPATED ANGLE OF
APPROACH TO THE SOUTHEAST UNITED STATES COAST MEANS THAN ONLY A
SMALL DEVIATION LEFT OR RIGHT OF THE TRACK WILL HAVE LARGE
IMPLICATIONS IN BOTH TIME AND LOCATION OF LANDFALL.  IN FACT...THE
WIND SPEED PROBABILITY PRODUCT INCLUDED WITH THIS ADVISORY PACKAGE
SHOWS THAT THE CHANCES OF HURRICANE-FORCE WINDS ARE ABOUT EQUAL AT
EACH SPECIFIC LOCATION ALONG THE COAST FROM FLORIDA THROUGH THE
CAROLINAS.

FORECAST POSITIONS AND MAX WINDS

INITIAL      02/2100Z 20.4N  72.7W    55 KT
12HR VT     03/0600Z 20.9N  73.1W    55 KT
24HR VT     03/1800Z 22.2N  74.0W    60 KT
36HR VT     04/0600Z 23.5N  75.5W    65 KT
48HR VT     04/1800Z 25.4N  77.2W    70 KT
72HR VT     05/1800Z 30.5N  80.5W    70 KT
96HR VT     06/1800Z 38.0N  78.0W    30 KT...INLAND
120HR VT     07/1800Z 47.0N  66.0W    25 KT...REMNANT LOW

$$
FORECASTER RHOME/KNABB




WTNT43 KNHC 030256
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT TUE SEP 02 2008

THE LAST COUPLE OF FIXES FROM THE RECONNAISSANCE AIRCRAFT
INDICATED THAT HANNA WAS MOVING SLOWLY EASTWARD.  IT SEEMS THAT
HANNA IS MAKING A SMALL COUNTER-CLOCKWISE LOOP BETWEEN HISPANIOLA
AND THE SOUTHEASTERN BAHAMAS.  I HAVE TO GIVE SOME CREDIT TO THE
GFDL AND HWRF MODELS WHICH PREDICTED THIS LOOP A FEW DAYS AGO...
HOWEVER THEY INDICATED THAT HANNA WOULD BE A LITTLE FURTHER NORTH
WHEN IT OCCURRED.  SINCE THE AIRCRAFT DEPARTED HANNA THE CLOUD
PATTERN HAS CONTINUED TO DEGRADE...AND IT IS POSSIBLE THAT HANNA
HAS WEAKENED EVEN MORE.  HOWEVER...WE WILL KEEP THE INITIAL
INTENSITY AT 55 KT SINCE ANOTHER AIRCRAFT IS SCHEDULED TO
INVESTIGATE THE STORM AROUND 0600 UTC.

STRONG NORTHWESTERLY UPPER-LEVEL WINDS CONTINUE TO SHEAR HANNA.
BUT...THE GLOBAL MODELS FORECAST AN UPPER-LEVEL LOW TO CUT-OFF TO
THE NORTHWEST OF HANNA VERY SOON...AND THERE IS SOME EVIDENCE IN
WATER VAPOR IMAGERY THAT THIS IS BEGINNING TO OCCUR.  AS THE
UPPER-LOW CUTS-OFF IT IS FORECAST TO DROP SOUTHWARD WHICH SHOULD
TURN THE UPPER-FLOW OVER THE STORM FROM THE SOUTH AND SOUTHEAST...
WHICH WOULD BE MORE FAVORABLE FOR STRENGTHENING DURING THE NEXT
COUPLE OF DAYS.  THE NEW INTENSITY FORECAST IS SIMILAR TO THE
PREVIOUS ADVISORY AND IS CLOSE TO THE CONSENSUS OF THE GUIDANCE.  AT
96 HOURS...HANNA WAS MAINTAINED AS A TROPICAL STORM...BECAUSE IT IS
PREDICTED TO BE FAIRLY CLOSE TO THE COAST OF THE NORTHEAST UNITED
STATES AND THERE COULD STILL BE TROPICAL STORM FORCE WINDS OVER
WATER AT THAT TIME.

THE TRACK MODELS SUGGEST THAT HANNA WILL BEGIN MOVING NORTHWESTWARD
VERY SOON AS THE LARGE UPPER-LEVEL TROUGH OFF THE NORTHEAST UNITED
STATES COAST LIFTS NORTHWARD...ALLOWING THE SUBTROPICAL RIDGE OVER
THE ATLANTIC TO BUILD WESTWARD.  THIS PATTERN IS FORECAST TO STEER
HANNA ON A GENERAL NORTHWESTWARD MOTION WITH SOME INCREASE IN
FORWARD SPEED OVER THE NEXT COUPLE OF DAYS.  SOME OF THE TRACK
MODELS HAVE SHIFTED A LITTLE EASTWARD...BUT NOT ENOUGH TO WARRANT A
CHANGE TO THE OFFICIAL FORECAST.  THE NEW TRACK HAS BEEN ADJUSTED
EASTWARD DURING THE FIRST 24-36 HOURS DUE TO THE MORE EASTWARD
INITIAL LOCATION...BUT THEREAFTER IT REMAINS VERY CLOSE TO THE
PREVIOUS ADVISORY.  AS A REMINDER...ONE SHOULD NOT FOCUS ON THE
EXACT TRACK AS SMALL DEVIATIONS LEFT OR RIGHT WOULD HAVE LARGE
IMPLICATIONS ON BOTH THE TIME AND LOCATION OF LANDFALL.  A G-IV
MISSION WAS FLOWN THIS EVENING AND THE DATA GATHERED BY THIS
AIRCRAFT SHOULD GET ASSIMILATED INTO THE 0000 UTC MODEL GUIDANCE.

FORECAST POSITIONS AND MAX WINDS

INITIAL      03/0300Z 20.5N  72.4W    55 KT
12HR VT     03/1200Z 21.3N  72.3W    55 KT
24HR VT     04/0000Z 22.8N  73.6W    60 KT
36HR VT     04/1200Z 24.4N  75.5W    65 KT
48HR VT     05/0000Z 26.4N  77.4W    70 KT
72HR VT     06/0000Z 32.5N  80.5W    75 KT...INLAND
96HR VT     07/0000Z 41.0N  75.5W    35 KT...INLAND
120HR VT     08/0000Z 50.0N  60.0W    35 KT...EXTRATROPICAL

$$
FORECASTER BROWN/AVILA




WTNT43 KNHC 030843
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT WED SEP 03 2008

FIXES FROM AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT
INDICATE HANNA HAS ALMOST COMPLETED A TIGHT CYCLONIC LOOP AND IS
NOW POSSIBLY TURNING SLOWLY NORTHWARD. THE INITIAL INTENSITY WAS
DECREASED TO COME MORE IN LINE WITH THE CENTRAL PRESSURE...WHICH IS
ESTIMATED TO BE 993 MB BASED ON A DROPSONDE REPORT THAT ALSO
MEASURED 25-KT SURFACE WINDS.

THE INITIAL MOTION ESTIMATE IS 360/02. THERE IS NO SIGNIFICANT
CHANGE TO THE PREVIOUS TRACK OR INTENSITY FORECAST REASONINGS.
HANNA IS EXPECTED TO GRADUALLY ACCELERATE NORTHWESTWARD OVER THE
NEXT 72 HOURS AND MAKE LANDFALL OVER THE SOUTHEASTERN UNITED STATES
...POSSIBLY IN THE SOUTH CAROLINA AREA. IT IS WORTH MENTIONING THAT
THE 00Z MODEL RUNS CONTAINED UPPER-AIR DATA FROM DROPSONDES
RELEASED AROUND HANNAFROM THE NOAA GULFSTREAM-IV JET AIRCRAFT...
WHICH USUALLY PRODUCES BETTER TRACK FORECASTS. THE OFFICIAL
FORECAST IS SIMILAR TO THE PREVIOUS TRACK AND IS CLOSE TO THE NHC
MODEL CONSENSUS.

THE INTENSITY FORECAST BASICALLY REMAINS UNCHANGED AND FOLLOWS THE
SHIPS INTENSITY MODEL...WITH HANNA EXPECTED TO REGAIN HURRICANE
STATUS BY 36 HOURS AND CONTINUE TO INTENSIFY UNTIL LANDFALL OCCURS.

FORECAST POSITIONS AND MAX WINDS

INITIAL      03/0900Z 20.2N  72.2W    50 KT
12HR VT     03/1800Z 21.5N  72.8W    55 KT
24HR VT     04/0600Z 23.2N  74.1W    60 KT
36HR VT     04/1800Z 24.8N  76.0W    65 KT
48HR VT     05/0600Z 27.2N  78.1W    75 KT
72HR VT     06/0600Z 33.7N  80.0W    70 KT...INLAND
96HR VT     07/0600Z 42.5N  71.5W    35 KT...EXTRATROPICAL INLAND
120HR VT     08/0600Z 51.0N  55.0W    35 KT...EXTRATROPICAL INLAND

$$
FORECASTER STEWART




WTNT43 KNHC 031500
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  27
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT WED SEP 03 2008

THERE HAVE BEEN SOME STRUCTURAL CHANGES WITH HANNA TODAY AS IT
INTERACTS WITH THE UPPER-LEVEL LOW MOVING THROUGH THE NORTHWESTERN
BAHAMAS.  THE WIND FIELD HAS EXPANDED IN THE NORTHERN SEMICIRCLE
AND THE LOW-LEVEL CIRCULATION CENTER HAS BECOME LESS WELL DEFINED.
VISIBLE IMAGERY SUGGESTS MULTIPLE LOW-LEVEL SWIRLS COMING OUT OF
THE DEEP CONVECTION TO THE NORTH OF A MEAN CENTER...AND THE
SYSTEM'S CONVECTIVE BANDS ARE WELL REMOVED FROM THE CORE.  THE
RECONNAISSANCE MISSION THAT ENDED AROUND 12Z REPORTED SOME SFMR
WINDS OF UP TO 45 KT ABOUT 70 NM FROM THE CENTER...AND THE INITIAL
INTENSITY ESTIMATE REMAINS 50 KT.

BECAUSE THE CENTER IS NOT WELL DEFINED...THE INTIAL MOTION IS HARD
TO GAUGE.  MY BEST ESTIMATE IS 360/5...AND THIS COULD BE THE START
OF THE EXPECTED NORTHWESTWARD TURN.  THE STEERING FLOW SHOULD
BECOME BETTER DEFINED OVER THE NEXT 24-48 HOURS AS THE UPPER LOW
MOVES WEST-SOUTHWESTWARD AND MID-LEVEL RIDGING BUILDS IN BEHIND THE
LARGE DEEP-LAYER LOW OFF THE UPPER U.S. EAST COAST.  MODEL GUIDANCE
RESPONDS TO THIS PATTERN WITH A NORTHWESTWARD ACCELERATION WITH A
RECURVATURE AROUND THE MID-LEVEL RIDGE IN ABOUT THREE DAYS.  THE
GUIDANCE HAS BEEN TOO FAST WITH THIS SCENARIO OVER THE PAST COUPLE
OF DAYS...AND GIVEN THE POOR CORE STRUCTURE OF HANNA I AM INCLINED
TO THINK THAT SUBSEQUENT INTERACTION WITH THE UPPER STEERING MAY BE
A LITTLE OVERDONE...AT LEAST INITIALLY.  THE OFFICIAL FORECAST IS
IN BEST AGREEMENT WITH THE ECMWF AND UKMET IN TERMS OF SPEED...WITH
THE GFS/HWRF/GFDL SHOWING A MORE VERTICAL SYSTEM MOVING MORE
RAPIDLY.  THE GUIDANCE HAS ALSO BEEN TRENDING EASTWARD OVER THE
PAST FEW CYCLES...AND I HAVE SHIFTED THE TRACK SLIGHTLY IN THAT
DIRECTION.

WESTERLY SHEAR AND DRY AIR ASSOCIATED WITH THE UPPER LOW WILL
INHIBIT DEVELOPMENT IN THE SHORT TERM BUT SHOULD DIMINISH OVER THE
NEXT COUPLE OF DAYS...TO BE REPLACED WITH MODERATE SOUTHEASTERLY
SHEAR.  THIS PATTERN WOULD PERMIT SOME RE-INTENSIFICATION...BUT
HANNA WILL NEED TO RECREATE AN INNER CORE IN ORDER TO INTENSIFY
SUBSTANTIALLY.  THE AVAILABLE GUIDANCE STILL BRINGS HANNA TO
MINIMAL HURRICANE INTENSITY AND THE OFFICIAL FORECAST IS JUST ABOVE
THIS GUIDANCE.


FORECAST POSITIONS AND MAX WINDS

INITIAL      03/1500Z 20.6N  71.8W    50 KT
12HR VT     04/0000Z 21.5N  72.0W    50 KT
24HR VT     04/1200Z 23.4N  73.3W    55 KT
36HR VT     05/0000Z 25.2N  75.2W    60 KT
48HR VT     05/1200Z 27.3N  77.1W    65 KT
72HR VT     06/1200Z 33.0N  79.0W    70 KT
96HR VT     07/1200Z 42.0N  71.0W    35 KT...INLAND EXTRATROPICAL
120HR VT     08/1200Z 47.0N  60.0W    35 KT...EXTRATROPICAL

$$
FORECASTER FRANKLIN



000

WTNT43 KNHC 032059
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  28
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT WED SEP 03 2008

AN ASCAT PASS FROM 14Z REVEALED THAT THE LOW-LEVEL CIRCULATION OF
HANNA WAS BECOMING ELONGATED IN RESPONSE TO THE ASYMMETRIC
DISTRIBUTION OF CONVECTION.  IN SPITE OF THIS...DATA FROM THE
RECONNAISSANCE AIRCRAFT INDICATE THAT HANNA IS BECOMING A LITTLE
BETTER ORGANIZED.  TROPICAL STORM FORCE WINDS HAVE RETURNED TO THE
SOUTHWEST QUADRANT AND THE PRESSURE HAS FALLEN TO 989 MB.  THE
AIRCRAFT DATA CONTINUE TO SUGGEST THAT THE MAXIMUM WINDS ARE ABOUT
50 KT.

A MORE DEFINITIVE NORTHWARD MOTION HAS COMMENCED...WITH THE INITIAL
ESTIMATE BEING 360/10.   THE UPPER LOW OFF OF NEW ENGLAND IS
BEGINNING TO MOVE OUT...AND AS IT DOES SO MID-LEVEL RIDGING WILL
BUILD IN BEHIND IT.  HANNA SEEMS TO BE FOLLOWING THE CONVECTION
FAIRLY WELL...AND I'VE HAD TO SPEED UP MY PREVIOUS FORECAST A
LITTLE BIT.  THE OFFICIAL FORECAST IS IN BEST AGREEMENT WITH A
BLEND OF THE ECMWF AND THE GFS.  THE HWRF AND GFDL CONTINUE TO BE
FASTER THAN THE OFFICIAL FORECAST...AND IF HANNA DEVELOPS FASTER
THAN SHOWN BELOW ADDITIONAL TIMING ADJUSTMENTS MAY NEED TO BE MADE.
IT'S WORTH NOTING THAT CONNECTING THE 48 AND 72 HOUR FORECAST POINTS
WITH A STRAIGHT LINE GIVES A MISLEADING UNDERESTIMATE OF THE
THREAT TO THE GEORGIA AND SOUTH CAROLINA COASTS.  ONLY A GRADUAL
RIGHT TURN IS EXPECTED AFTER 48 HOURS.

AS THE UPPER LOW IN THE BAHAMAS AND HANNA SEPARATE...THE SOUTHERLY
SHEAR OVER THE CYCLONE WILL TURN SOUTHEASTERLY AND LESSEN.  THIS IS
EXPECTED TO PROVIDE A MORE FAVORABLE ENVIRONMENT FOR
STRENGTHENING...ALTHOUGH NONE OF THE OBJECTIVE AIDS SHOWS VERY
MUCH.  THE SHIPS AND LGEM BRING THE SYSTEM ONLY TO 60 KT...AND THE
HWRF NOT QUITE THAT HIGH.  THE OFFICIAL FORECAST IS IN GOOD
AGREEMENT WITH THE GFDL WHICH BRINGS HANNA TO 70 KT PRIOR TO
LANDFALL.


FORECAST POSITIONS AND MAX WINDS

INITIAL      03/2100Z 21.9N  71.9W    50 KT
12HR VT     04/0600Z 23.2N  72.7W    55 KT
24HR VT     04/1800Z 25.2N  74.5W    60 KT
36HR VT     05/0600Z 27.4N  76.6W    65 KT
48HR VT     05/1800Z 30.0N  78.5W    70 KT
72HR VT     06/1800Z 36.8N  76.9W    50 KT...INLAND
96HR VT     07/1800Z 44.5N  67.0W    35 KT...EXTRATROPICAL
120HR VT     08/1800Z 48.0N  55.0W    35 KT...EXTRATROPICAL

$$
FORECASTER FRANKLIN




WTNT43 KNHC 040254
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  29
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT WED SEP 03 2008

HANNA HAS BEEN A TENACIOUS TROPICAL CYCLONE. SINCE ITS FORMATION IT
HAS FOUGHT TWO UPPER-LEVEL LOWS...STRONG NORTHERLY SHEAR AND THE
EFFECTS OF LAND. FURTHERMORE...AT TIMES HANNA HAS RESEMBLED A
SUBTROPICAL CYCLONE.  SURFACE AND AIRCRAFT OBSERVATIONS TONIGHT
CONTINUE TO SHOW THAT HANNA HAS A LARGE CIRCULATION AND SATELLITE
IMAGES SUGGEST THAT THE SHEAR IS DECREASING AND HANNA IS DEVELOPING
UPPER-LEVEL OUTFLOW. THESE CHANGES IN THE UPPER FLOW OVER HANNA
HAVE BEEN ACCURATELY FORECAST BY MOST OF THE NUMERICAL WEATHER
PREDICTION MODELS.  THE INITIAL INTENSITY IS 55 KNOTS...AND IS
BASED ON A 68 KT FLIGHT-LEVEL WIND MEASURED AS THE PLANE DEPARTED
THE CYCLONE. WITH THE MORE FAVORABLE UPPER-LEVEL ENVIRONMENT...SOME
INTENSIFICATION IS INDICATED IN THE OFFICIAL FORECAST.  HANNA IS
FORECAST TO REGAIN HURRICANE STATUS IN A DAY OR TWO BUT IT COULD
OCCUR EARLIER. NONE OF THE GUIDANCE INTENSIFIES HANNA BEYOND 70
KNOTS.

THE CENTER HAS BEEN ROTATING AROUND A LARGE CYCLONIC GYRE AND FIXES
FROM THE RECONNAISSANCE PLANE AND DATA FROM A NOAA BUOY SUGGEST
THAT THE INITIAL MOTION IS 335/11. SOME OF THIS MOTION COULD HAVE
RESULTED FROM REFORMATION OF THE CENTER. SINCE THE SUBTROPICAL RIDGE
IS EXPANDING TO THE NORTHEAST OF HANNA...A NORTHWEST MOTION SHOULD
CONTINUE DURING THE NEXT DAY OR TWO WITH A GRADUAL TURN TO THE
NORTH AROUND THE WESTERN EDGE OF THE HIGH.  THE TRACK
MODELS ARE NOT TIGHTLY CLUSTERED AND THE CONFIDENCE IN THE TRACK
FORECAST IS NOT VERY HIGH. HOWEVER...THE MIDDLE OF THE GUIDANCE
ENVELOPE HAS HANNA MOVING OVER OR VERY CLOSE TO THE COAST OF THE
CAROLINAS.  BECAUSE HANNA IS A LARGE CYCLONE...A HURRICANE WATCH
WILL LIKELY BE REQUIRED FOR A PORTION OF THE SOUTHEASTERN UNITED
STATES COAST EARLY THURSDAY.

A NOAA JET HAS SAMPLED THE ENVIRONMENT TONIGHT AND THE DATA IS BEING
USED TO INITIALIZE THE 00Z GLOBAL MODEL RUNS.


FORECAST POSITIONS AND MAX WINDS

INITIAL      04/0300Z 23.2N  72.1W    55 KT
12HR VT     04/1200Z 24.7N  73.1W    55 KT
24HR VT     05/0000Z 26.9N  75.0W    60 KT
36HR VT     05/1200Z 29.3N  77.3W    65 KT
48HR VT     06/0000Z 32.0N  79.0W    70 KT
72HR VT     07/0000Z 39.5N  74.0W    50 KT...INLAND
96HR VT     08/0000Z 46.5N  63.0W    35 KT...EXTRATROPICAL
120HR VT     09/0000Z 49.0N  47.0W    35 KT...EXTRATROPICAL

$$
FORECASTER AVILA



000

WTNT43 KNHC 040900
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  30
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT THU SEP 04 2008

LOOKS CAN CERTAINLY BE DECEIVING.  HANNA HAS NOT BEEN PRODUCING VERY
MUCH DEEP CONVECTION SINCE AN EARLIER STRONG BURST DIED AFTER ABOUT
04Z...AS THE UPPER-LEVEL LOW TO ITS WEST CONTINUES TO IMPOSE STRONG
SOUTHERLY SHEAR.  NEVERTHELESS...HANNA HAS A LARGE AND ROBUST
CIRCULATION...AND A NOAA RECONNAISSANCE AIRCRAFT HAS RECENTLY
REPORTED A MINIMUM CENTRAL PRESSURE OF 990 MB.  FLIGHT-LEVEL WINDS
AT 850 MB HAVE BEEN AS STRONG AS 65 KT...AND NUMEROUS SFMR VALUES
OF 55-60 KT HAVE BEEN RETRIEVED.  I HAVE NO GOOD REASON TO DISCOUNT
THE SFMR WINDS...SO THE INITIAL INTENSITY IS INCREASED TO 60 KT.
GIVEN THAT THE SOUTHERLY SHEAR IS FORECAST BY THE DYNAMICAL MODELS
TO PERSIST OVER HANNA EVEN AS IT GAINS LATITUDE DURING THE NEXT
COUPLE OF DAYS...STRENGTHENING WOULD AT FIRST GLANCE SEEM UNLIKELY.
CONSISTENT WITH THAT THINKING...THE GFDL AND HWRF SHOW LITTLE
CHANGE IN STRENGTH OR EVEN SOME WEAKENING...EXCEPT MUCH LATER WHEN
HANNA BECOMES AN EXTRATROPICAL CYCLONE.  ON THE OTHER HAND...THE
SHIPS AND LGEM...DESPITE DIAGNOSING LITTLE CHANGE IN
SHEAR...FORECAST A LITTLE STRENGTHENING TO HURRICANE STATUS.  A
CONSENSUS OF THESE VARIOUS MODELS WOULD YIELD A FLAT 60 KT
INTENSITY FORECAST UNTIL HANNA PASSES NEAR OR OVER THE
CAROLINAS...BUT FOR CONTINUITY AND SINCE HANNA IS ALREADY PRODUCING
WINDS JUST SHY OF HURRICANE STRENGTH....65 KT IS STILL SHOWN
EXPLICITLY IN THE FORECAST.  GRADUAL WEAKENING IS THEN FORECAST AS
HANNA ACCELERATES NORTHEASTWARD AND BECOMES EXTRATROPICAL.

DESPITE HAVING AIRCRAFT FIXES...THE INITIAL MOTION IS HARD TO
GAGE...PROBABLY DUE TO THE SPRAWLING NATURE OF THE
CIRCULATION...BUT THE INITIAL MOTION ESTIMATE IS 320/10.  HANNA
SHOULD ROUND THE BUILDING WESTERN ATLANTIC RIDGE AND ROUGHLY HUG
THE EAST COAST OF THE UNITED STATES...BUT PASSING NEAR OR OVER THE
COAST OF THE CAROLINAS ALONG THE WAY.  PERHAPS DUE IN PART TO THE
BENEFIT OF DATA FROM THE NOAA G-IV JET MISSION LAST NIGHT...THE
LATEST MODEL TRACKS HAVE COME INTO A LITTLE TIGHTER AGREEMENT...AND
IN GENERAL THEY HAVE SHIFTED SLIGHTLY TO THE LEFT.  THE NEW TRACK
FORECAST IS SHIFTED JUST SLIGHTLY LEFT OF THE PREVIOUS ONE...TO BE
CLOSER TO THE CONSENSUS.  AS ALWAYS...ONE SHOULD NOT FOCUS ON THE
EXACT FORECAST OF THE CENTER...ESPECIALLY SINCE MUCH OF THE WEATHER
ASSOCIATED WITH HANNA IS WELL-REMOVED FROM THE CENTER.


FORECAST POSITIONS AND MAX WINDS

INITIAL      04/0900Z 24.0N  72.8W    60 KT
12HR VT     04/1800Z 25.3N  74.1W    60 KT
24HR VT     05/0600Z 27.5N  76.6W    60 KT
36HR VT     05/1800Z 30.3N  78.4W    65 KT
48HR VT     06/0600Z 33.5N  78.4W    65 KT
72HR VT     07/0600Z 41.0N  72.5W    50 KT...INLAND
96HR VT     08/0600Z 48.5N  59.0W    45 KT...EXTRATROPICAL
120HR VT     09/0600Z 51.5N  41.0W    45 KT...EXTRATROPICAL

$$
FORECASTER KNABB




WTNT43 KNHC 041450
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  31
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT THU SEP 04 2008

VERY DRY AIR ASSOCIATED WITH THE UPPER-LEVEL LOW OVER THE
NORTHWESTERN BAHAMAS IS CHOKING OFF CONVECTION NEAR THE CORE OF
HANNA...AND THE CYCLONE HAS A VERY SUBTROPICAL APPEARANCE.
CONVECTION HAS DIMINISHED SUBSTANTIALLY OVER THE PAST 6-12 HOURS
AND THE HIGHEST FLIGHT-LEVEL AND SFMR WINDS HAVE COME DOWN AS WELL.
BASED ON SOME 52 KT SFMR WINDS AROUND 11Z...THE INITIAL INTENSITY
IS LOWERED TO 55 KT.

CONDITIONS ARE NOT CONDUCIVE TO STRENGTHENING RIGHT NOW...WITH
MODERATE SOUTHERLY SHEAR AND POOR THERMODYNAMICS.  THE GFS SUGGESTS
THAT DRY AIR IS LIKELY TO CONTINUE TO BE AN ISSUE UP TO LANDFALL.
HOWEVER...AS HANNA AND THE UPPER LOW BEGIN TO SEPARATE SOME OF THE
GLOBAL MODELS...INCLUDING THE GFS...SUGGEST THAT THE SHEAR WILL
LESSEN SOMEWHAT.  THIS WOULD ALLOW FOR SOME INTENSIFICATION...AND
SO THE OFFICIAL FORECAST CONTINUES TO SHOW HANNA ATTAINING
HURRICANE STRENGTH.  THIS IS IN GOOD AGREEMENT WITH THE
HWRF...ALTHOUGH THE GFDL AND SHIPS GUIDANCE IS LOWER.

THE INITIAL MOTION IS 315/10.  THE FORECAST SCENARIO IS UNCHANGED
FROM PREVIOUS ADVISORIES.  MID-LEVEL HIGH PRESSURE IS BUILDING OVER
THE WESTERN ATLANTIC AS A DEEP LAYER LOW MOVES AWAY FROM NEW
ENGLAND.  HANNA IS EXPECTED TO RECURVE AROUND THE PERIPHERY OF THE
HIGH AHEAD OF A MID-LATITUDE SHORT WAVE TROUGH IN THE WESTERLIES.
MODEL GUIDANCE REMAINS IN FAIRLY GOOD AGREEMENT AND LITTLE CHANGE
TO THE FORECAST TRACK IS REQUIRED.  THE OFFICIAL FORECAST IS
SLIGHTLY TO THE RIGHT OF THE MODEL CONSENSUS BECAUSE THE BETTER
PERFORMING MODELS THIS YEAR...NAMELY THE GFS AND GFDL...ARE ON THE
RIGHT SIDE OF THE GUIDANCE ENVELOPE.  BECAUSE OF THE LARGE...
SPRAWLING NATURE OF THE CIRCULATION...THE EXACT TRAJECTORY OF THE
CENTER IS RELATIVELY UNIMPORTANT.


FORECAST POSITIONS AND MAX WINDS

INITIAL      04/1500Z 24.5N  73.5W    55 KT
12HR VT     05/0000Z 26.2N  75.2W    55 KT
24HR VT     05/1200Z 28.7N  77.2W    60 KT
36HR VT     06/0000Z 31.7N  78.2W    65 KT
48HR VT     06/1200Z 35.4N  77.4W    55 KT
72HR VT     07/1200Z 43.0N  69.5W    40 KT...INLAND
96HR VT     08/1200Z 50.0N  54.0W    40 KT...EXTRATROPICAL
120HR VT     09/1200Z 51.5N  37.5W    45 KT...EXTRATROPICAL

$$
FORECASTER FRANKLIN




WTNT43 KNHC 041514
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  31...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT THU SEP 04 2008

...CORRECT STATUS AT 48 AND 72 HR...

VERY DRY AIR ASSOCIATED WITH THE UPPER-LEVEL LOW OVER THE
NORTHWESTERN BAHAMAS IS CHOKING OFF CONVECTION NEAR THE CORE OF
HANNA...AND THE CYCLONE HAS A VERY SUBTROPICAL APPEARANCE.
CONVECTION HAS DIMINISHED SUBSTANTIALLY OVER THE PAST 6-12 HOURS
AND THE HIGHEST FLIGHT-LEVEL AND SFMR WINDS HAVE COME DOWN AS WELL.
BASED ON SOME 52 KT SFMR WINDS AROUND 11Z...THE INITIAL INTENSITY
IS LOWERED TO 55 KT.

CONDITIONS ARE NOT CONDUCIVE TO STRENGTHENING RIGHT NOW...WITH
MODERATE SOUTHERLY SHEAR AND POOR THERMODYNAMICS.  THE GFS SUGGESTS
THAT DRY AIR IS LIKELY TO CONTINUE TO BE AN ISSUE UP TO LANDFALL.
HOWEVER...AS HANNA AND THE UPPER LOW BEGIN TO SEPARATE SOME OF THE
GLOBAL MODELS...INCLUDING THE GFS...SUGGEST THAT THE SHEAR WILL
LESSEN SOMEWHAT.  THIS WOULD ALLOW FOR SOME INTENSIFICATION...AND
SO THE OFFICIAL FORECAST CONTINUES TO SHOW HANNA ATTAINING
HURRICANE STRENGTH.  THIS IS IN GOOD AGREEMENT WITH THE
HWRF...ALTHOUGH THE GFDL AND SHIPS GUIDANCE IS LOWER.

THE INITIAL MOTION IS 315/10.  THE FORECAST SCENARIO IS UNCHANGED
FROM PREVIOUS ADVISORIES.  MID-LEVEL HIGH PRESSURE IS BUILDING OVER
THE WESTERN ATLANTIC AS A DEEP LAYER LOW MOVES AWAY FROM NEW
ENGLAND.  HANNA IS EXPECTED TO RECURVE AROUND THE PERIPHERY OF THE
HIGH AHEAD OF A MID-LATITUDE SHORT WAVE TROUGH IN THE WESTERLIES.
MODEL GUIDANCE REMAINS IN FAIRLY GOOD AGREEMENT AND LITTLE CHANGE
TO THE FORECAST TRACK IS REQUIRED.  THE OFFICIAL FORECAST IS
SLIGHTLY TO THE RIGHT OF THE MODEL CONSENSUS BECAUSE THE BETTER
PERFORMING MODELS THIS YEAR...NAMELY THE GFS AND GFDL...ARE ON THE
RIGHT SIDE OF THE GUIDANCE ENVELOPE.  BECAUSE OF THE LARGE...
SPRAWLING NATURE OF THE CIRCULATION...THE EXACT TRAJECTORY OF THE
CENTER IS RELATIVELY UNIMPORTANT.


FORECAST POSITIONS AND MAX WINDS

INITIAL      04/1500Z 24.5N  73.5W    55 KT
12HR VT     05/0000Z 26.2N  75.2W    55 KT
24HR VT     05/1200Z 28.7N  77.2W    60 KT
36HR VT     06/0000Z 31.7N  78.2W    65 KT
48HR VT     06/1200Z 35.4N  77.4W    55 KT...INLAND
72HR VT     07/1200Z 43.0N  69.5W    40 KT...EXTRATROPICAL
96HR VT     08/1200Z 50.0N  54.0W    40 KT...EXTRATROPICAL
120HR VT     09/1200Z 51.5N  37.5W    45 KT...EXTRATROPICAL

$$
FORECASTER FRANKLIN




WTNT43 KNHC 042101
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  32
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT THU SEP 04 2008

THE RECONNAISSANCE AIRCRAFT INVESTIGATING HANNA IS FINDING THE
CIRCULATION CENTER AT 850 MB DISPLACED TO THE NORTHWEST OF THE MEAN
CENTER OF ROTATION APPARENT IN THE LOW CLOUD LINES.  THERE ARE ALSO
MULTIPLE SWIRLS...BUT IT DOES APPEAR THAT THE LOW-LEVEL CENTER HAS
JUMPED A LITTLE BIT TO THE WEST IN RESPONSE TO THE CONVECTIVE
ASYMMETRY.  ALTHOUGH A COUPLE MORE SHIFTS ARE POSSIBLE...THE
ORIENTATION OF THE SHEAR SHOULD TURN MORE SOUTHERLY WITH
TIME...THAT IS...MORE ALONG THE TRACK...AND THEN HAVE LESS OF AN
IMPACT ON THE TRACK.  THE BASIC FORECAST PHILOSOPHY IS UNCHANGED.
THE NEW TRACK FORECAST IS VERY CLOSE TO THE PREVIOUS ONE WITH ONLY
A SLIGHT LEFTWARD SHIFT...AND IS NEAR THE MODEL CONSENSUS.

RECONNAISSANCE DATA THUS FAR DO NOT SUPPORT ANY INCREASE IN THE
INTENSITY ESTIMATE.  WATER VAPOR IMAGERY CONTINUES TO SHOW VERY DRY
AIR IMPINGING ON HANNA FROM THE SOUTHEAST...AND THIS IS EXPECTED TO
CONTINUE.  WHILE THE VERTICAL SHEAR IS FORECAST TO DIMINISH A
LITTLE PRIOR TO LANDFALL...NONE OF THE OBJECTIVE GUIDANCE MODELS
NOW MAKE HANNA A HURRICANE AND THE OFFICIAL INTENSITY FORECAST NOW
TOPS OUT AT 60 KT.  HURRICANE WATCHES WILL REMAIN IN EFFECT FOR THE
POSSIBILITY THAT HANNA BECOMES A LITTLE STRONGER THAN
FORECAST...AND PEOPLE ARE REMINDED THAT THERE IS VERY LITTLE
DIFFERENCE BETWEEN A STRONG TROPICAL STORM AND A MINIMAL HURRICANE.


FORECAST POSITIONS AND MAX WINDS

INITIAL      04/2100Z 25.5N  75.0W    55 KT
12HR VT     05/0600Z 27.2N  76.4W    55 KT
24HR VT     05/1800Z 30.3N  78.0W    60 KT
36HR VT     06/0600Z 33.9N  78.3W    60 KT...ON THE COAST
48HR VT     06/1800Z 37.5N  76.5W    50 KT...INLAND
72HR VT     07/1800Z 46.0N  65.5W    40 KT...EXTRATROPICAL
96HR VT     08/1800Z 51.0N  50.0W    40 KT...EXTRATROPICAL
120HR VT     09/1800Z 52.5N  32.5W    45 KT...EXTRATROPICAL

$$
FORECASTER FRANKLIN




WTNT43 KNHC 050246
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  33
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT THU SEP 04 2008

A RECONNAISSANCE AIRCRAFT MEASURED A MINIMUM PRESSURE OF 987 MB AND
60 KNOTS AT FLIGHT LEVEL ON ITS WAY HOME A FEW HOURS AGO. SINCE
THEN SATELLITE IMAGES HAVE SHOWN AN INCREASE IN THUNDERSTORM
ACTIVITY AND THERE ARE SOME INDICATIONS THAT THE CENTER COULD BE
UNDER THE CONVECTION OR VERY NEAR THE SOUTHERN EDGE. THE CLOUD
PATTERN ON IR IMAGES INDICATE THAT HANNA LOOKS A LITTLE MORE
TROPICAL THAN EARLIER TODAY BUT THE CYCLONE STILL HAS A LARGE WIND
FIELD AND LACKS AN INNER CORE. INITIAL INTENSITY IS KEPT AT 55
KNOTS AND ANOTHER PLANE WILL BE IN THE AREA IN A FEW HOURS TO CHECK
IF THE WINDS HAVE INCREASED.  NONE OF THE GUIDANCE INDICATE
SIGNIFICANT STRENGTHENING AND THE OFFICIAL FORECAST BRINGS HANNA TO
60 KNOTS BEFORE IT REACHES THE UNITED STATES COAST. PEOPLE ARE
REMINDED THAT THERE IS VERY LITTLE DIFFERENCE BETWEEN A STRONG
TROPICAL STORM AND A MINIMAL HURRICANE...ONLY A FIVE KNOT
DIFFERENCE.

SURFACE DATA AND EXTRAPOLATION FROM EARLIER RECONNAISSANCE FIXES
INDICATE THAT HANNA IS MOVING TOWARD THE NORTHWEST OR 320 DEGREES
AT 12 KNOTS...STEERED BY STRONG SUBTROPICAL RIDGE OVER THE WESTERN
ATLANTIC. THE WESTERN EDGE OF THE RIDGE IS FORECAST TO BE ERODED BY
AN APPROACHING SHORT WAVE. THIS PATTERN SHOULD FORCE HANNA TO MOVE
ON A MORE NORTHERLY TRACK DURING THE NEXT 24 TO 48 HOURS WITH AN
INCREASE IN FORWARD SPEED. THEREAFTER...HANNA IS EXPECTED TO BE
FULLY EMBEDDED WITHIN THE MID-LATITUDE WESTERLIES AND RACE TO THE
NORTHEAST WHILE BECOMING EXTRATROPICAL.  THIS IS BASICALLY THE
SOLUTION PROVIDED BY MOST OF THE GUIDANCE.

IF HANNA BECOMES MORE TROPICAL AS SUGGESTED BY THE INCREASE IN
CONVECTION...THE WIND FIELD MOST LIKELY WILL CONTRACT A LITTLE BIT.


FORECAST POSITIONS AND MAX WINDS

INITIAL      05/0300Z 26.5N  76.3W    55 KT
12HR VT     05/1200Z 28.5N  77.7W    55 KT
24HR VT     06/0000Z 31.5N  78.5W    60 KT
36HR VT     06/1200Z 35.0N  78.0W    50 KT...INLAND
48HR VT     07/0000Z 39.0N  75.0W    40 KT...INLAND
72HR VT     08/0000Z 46.0N  62.0W    40 KT...EXTRATROPICAL
96HR VT     09/0000Z 50.5N  44.5W    40 KT...EXTRATROPICAL
120HR VT     10/0000Z 51.2N  27.0W    40 KT...EXTRATROPICAL

$$
FORECASTER AVILA



000

WTNT43 KNHC 050900
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  34
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT FRI SEP 05 2008

A RECONNAISSANCE AIRCRAFT CURRENTLY SAMPLING HANNA RECENTLY FOUND
PEAK FLIGHT-LEVEL WINDS OF 73 KT.  THIS WOULD NORMALLY CORRESPOND
TO SURFACE WINDS OF ABOUT 60 KT USING THE STANDARD REDUCTION.
HOWEVER...THE WINDS WERE FOUND IN AN AREA ABSENT OF DEEP CONVECTION
AND THE SFMR INSTRUMENT ONLY SHOWED ABOUT 51 KT IN THE SAME AREA.
IN ADDITION...A DROPSONDE RELEASED IN THE AREA HAD A SURFACE WIND
OF 57 KT.  THESE DATA SUGGEST THE INTENSITY REMAINS NEAR 55 KT.
HANNA HAS BEEN STRUGGLING TO GENERATE PERSISTENT DEEP CONVECTION
NEAR THE CENTER DUE TO SHEAR AND DRY AIR...ALTHOUGH THERE HAS BEEN
A RECENT BURST WITHIN THE LAST COUPLE OF HOURS.  WHILE THERE IS
SOME POTENTIAL FOR A LITTLE ADDITIONAL STRENGTHENING...ALL BUT ONE
OF THE INTENSITY MODELS KEEP HANNA JUST BELOW HURRICANE STRENGTH.
STILL...THERE IS LITTLE DIFFERENCE BETWEEN A STRONG TROPICAL STORM
AND A CATEGORY ONE HURRICANE...AND HANNA COULD REACH HURRICANE
STRENGTH BEFORE MOVING INLAND OVER THE SOUTHEASTERN UNITED STATES
IN ABOUT 24 HOURS.

HANNA IS BEING STEERED BY THE SUBTROPICAL RIDGE OVER THE WESTERN
ATLANTIC RESULTING IN A MOTION TOWARD THE NORTHWEST OR 320/17.
HANNA IS EXPECTED TO TURN TOWARD THE NORTH TODAY THEN NORTHEASTWARD
TONIGHT AND TOMORROW AS IT ROUNDS THE WESTERN PERIPHERY OF THE
RIDGE.  THEREAFTER...HANNA IS EXPECTED TO RACE NORTHEASTWARD AND
BECOME EXTRATROPICAL IN ABOUT 3 DAYS.  TRACK MODELS HAVE BEEN
TRENDING TOWARD THE WEST AND THE OFFICIAL FORECAST IS SHIFTED TO
THE LEFT THROUGH 36 HOURS.  HOWEVER...GIVEN HANNA'S LARGE
SIZE...ONE SHOULD NOT FOCUS ON THE EXACT TRACK AS THE INCLEMENT
WEATHER EXTENDS WELL BEYOND THE CENTER.

FORECAST POSITIONS AND MAX WINDS

INITIAL      05/0900Z 28.0N  78.0W    55 KT
12HR VT     05/1800Z 30.0N  78.8W    60 KT
24HR VT     06/0600Z 33.2N  79.1W    60 KT
36HR VT     06/1800Z 36.7N  77.2W    45 KT...INLAND
48HR VT     07/0600Z 40.6N  72.9W    40 KT...INLAND
72HR VT     08/0600Z 48.0N  58.0W    40 KT...EXTRATROPICAL
96HR VT     09/0600Z 50.5N  40.0W    40 KT...EXTRATROPICAL
120HR VT     10/0600Z 51.5N  23.5W    40 KT...EXTRATROPICAL

$$
FORECASTER RHOME




WTNT43 KNHC 051452
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  35
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT FRI SEP 05 2008

SATELLITE IMAGERY AND RADAR DATA FROM THE MELBOURNE WSR-88D INDICATE
THAT HANNA HAS BECOME A LITTLE BETTER ORGANIZED THIS MORNING...AS
THE LATEST CONVECTIVE BURST HAS PRODUCED AN INNER WIND CORE.
HOWEVER...THE RADAR-OBSERVED VELOCITIES DO NOT YET SUGGEST
INTENSIFICATION.  THE INITIAL INTENSITY REMAINS 55 KT.

THE CENTER OF HANNA JOGGED WESTWARD BETWEEN 06-12Z.  HOWEVER...THE
MELBOURNE RADAR SUGGEST THE CENTER HAS RESUMED A MORE NORTHWARD
MOTIONS...WITH THE INITIAL MOTION ESTIMATED AT 325/17.  HANNA IS
MOVING AROUND THE WESTERN END OF THE SUBTROPICAL RIDGE OVER THE
WESTERN ATLANTIC AND SHOULD ENTER THE WESTERLIES IN 24-48 HR.  THIS
SHOULD RESULT IN RECURVATURE TO THE NORTHEAST AND ACCELERATION.
ALL GUIDANCE AGREES WITH THIS SCENARIO...AND THERE ARE NO
SIGNIFICANT OUTLIERS AMONGST THE DYNAMICAL MODELS.  THE NEW
FORECAST TRACK IS ADJUSTED A LITTLE TO THE LEFT FOR THE FIRST 36 HR
TO ACCOUNT FOR THE INITIAL POSITION...AND IS CLOSE TO THE PREVIOUS
FORECAST TRACK THEREAFTER.

WHILE VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT ARE STILL
ISSUES...THE INCREASED ORGANIZATION SUGGESTS THE POSSIBILITY OF
STRENGTHENING BEFORE LANDFALL.  THUS...THE INTENSITY FORECAST CALLS
FOR A PEAK INTENSITY OF 60 KT NEAR LANDFALL.  NONE OF THE GUIDANCE
INDICATES THAT HANNA WILL REACH HURRICANE STRENGTH PRIOR TO
LANDFALL...ALTHOUGH THIS CANNOT BE RULED OUT.  THE CYCLONE SHOULD
WEAKEN AFTER LANDFALL AND BECOME EXTRATROPICAL IN ABOUT 48 HR.  THE
GFS AND UKMET SUGGEST THE POSSIBILITY OF DEEPENING AS AN
EXTRATROPICAL SYSTEM LATE IN THE PERIOD...AND THIS IS REFLECTED IN
THE 96 AND 120 HR FORECASTS.


FORECAST POSITIONS AND MAX WINDS

INITIAL      05/1500Z 28.9N  79.2W    55 KT
12HR VT     06/0000Z 31.2N  79.7W    60 KT
24HR VT     06/1200Z 34.5N  79.1W    55 KT...INLAND
36HR VT     07/0000Z 38.2N  76.1W    45 KT...INLAND
48HR VT     07/1200Z 42.5N  70.1W    40 KT...EXTRATROPICAL
72HR VT     08/1200Z 49.0N  52.5W    40 KT...EXTRATROPICAL
96HR VT     09/1200Z 50.5N  35.0W    45 KT...EXTRATROPICAL
120HR VT     10/1200Z 51.0N  18.5W    45 KT...EXTRATROPICAL

$$
FORECASTER BEVEN




WTNT43 KNHC 052038
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  36
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT FRI SEP 05 2008
 
REPORTS FROM AN AIR FORCE RESERVE HURRICANE HURRICANE HUNTER
AIRCRAFT INDICATE THAT HANNA IS JUST BELOW HURRICANE STRENGTH.  THE
STEPPED FREQUENCY MICROWAVE REPORTED TWO AREAS OF WIND OF ABOUT 65
KT.  HOWEVER...DROPSONDE DATA SUGGESTS THAT THE SFMR ESTIMATES WERE
A LITTLE TOO HIGH.  THE MAXIMUM 850 MB FLIGHT-LEVEL WINDS WERE 75
KT ABOUT 75 N MI EAST OF THE CENTER.  THE LAST REPORTED CENTRAL
PRESSURE WAS 984 MB...UP A LITTLE FROM THIS MORNING.  BASED ON ALL
THIS...THE INITIAL INTENSITY IS SET AT 60 KT.  IT SHOULD BE NOTED
THAT THERE IS NOT MUCH DIFFERENCE METEOROLOGICALLY BETWEEN A 60-KT
TROPICAL STORM AND A 65-KT HURRICANE.

THE MOTION IS A SOMEWHAT WOBBLY 360/17...WITH A RE-ANALYSIS OF
AIRCRAFT DATA SUGGESTING THIS MOTION BEGAN JUST AFTER THE 11Z
AIRCRAFT FIX.  HANNA IS MOVING AROUND THE WESTERN END OF THE
SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC AND SHOULD ENTER THE
WESTERLIES IN 24-36 HR.  THIS SHOULD RESULT IN RECURVATURE TO THE
NORTHEAST AND ACCELERATION.  ALL GUIDANCE AGREES WITH THIS
SCENARIO...AND THERE ARE NO SIGNIFICANT OUTLIERS AMONGST THE
DYNAMICAL MODELS.  THE NEW FORECAST TRACK IS ADJUSTED A LITTLE TO
THE RIGHT OF THE PREVIOUS TRACK AND LIES DOWN THE MIDDLE OF THE
GUIDANCE ENVELOPE.

VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT ARE STILL ISSUES FOR
HANNA...AND SIGNIFICANT STRENGTHENING APPEARS UNLIKELY BEFORE
LANDFALL.  HOWEVER...THERE IS A POSSIBILITY THAT A CONVECTIVE BURST
COULD CAUSE THE STORM TO REACH HURRICANE STRENGTH.  THE CYCLONE
SHOULD WEAKEN AFTER LANDFALL AND BECOME EXTRATROPICAL IN ABOUT 36
HR.  THE GFS AND UKMET CONTINUE TO SUGGEST THE POSSIBILITY OF
DEEPENING AS AN EXTRATROPICAL SYSTEM LATE IN THE FORECAST
PERIOD...AND THIS IS REFLECTED IN THE 96 AND 120 HR FORECASTS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      05/2100Z 30.8N  78.7W    60 KT
 12HR VT     06/0600Z 33.2N  78.5W    60 KT
 24HR VT     06/1800Z 36.7N  76.8W    50 KT...INLAND
 36HR VT     07/0600Z 40.7N  72.4W    45 KT...EXTRATROPICAL
 48HR VT     07/1800Z 44.5N  65.6W    40 KT...INLAND EXTRATROPICAL
 72HR VT     08/1800Z 50.0N  47.5W    40 KT...EXTRATROPICAL
 96HR VT     09/1800Z 51.0N  30.0W    45 KT...EXTRATROPICAL
120HR VT     10/1800Z 52.5N  14.0W    45 KT...EXTRATROPICAL
 
$$
FORECASTER BEVEN
 

WTNT43 KNHC 060255
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  37
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT FRI SEP 05 2008
 
DATA FROM A RECONNAISSACE PLANE INDICATE THAT THE SURFACE PRESSURE
HAS DROPPED TO 978 MB BUT WINDS HAVE NOT INCREASED. INITIAL
INTENSITY IS KEPT AT 60 KNOTS. THE AREA OF STRONG WINDS HAS BEEN
SHRINKING SINCE HANNA APPEARS TO BE MORE TROPICAL AND THERE IS A
PERSISTENT AND LARGE AREA OF DEEP CONVECTION NEAR THE CENTER. HANNA
COULD REACH THE COAST IN LESS THAN 12 HOURS AS A HURRICANE SINCE IT
ONLY NEEDS FIVE KNOTS TO BE ONE. HOWEVER...THERE IS NOT MUCH
DIFFERENCE BETWEEN A 60-KT TROPICAL STORM AND A 65-KT HURRICANE.    

RADAR AND RECONNAISSANCE FIXES INDICATE THAT HANNA IS MOVING
NORTHWARD AT 17 KNOTS. THE CYCLONE IS ALREADY EMBEDDED IN A STRONG
SOUTHERLY AND SOUTHWESTERLY FLOW...AND SOON HANNA SHOULD BEGIN TO
TURN TO THE NORTHEAST WITH AN INCREASE IN FORWARD SPEED. AFTER
LANDFALL...AS HANNA BECOMES FULLY INVOLVED WITH THE MID-LATITUDE
FLOW...IT SHOULD BECOME EXTRATROPICAL IN ABOUT 24 TO 36 HOURS.
DURING THIS PERIOD...HANNA WILL BE MOVING VERY CLOSE TO OR OVER THE
NORTHEAST COAST OF THE UNITED STATES.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/0300Z 32.4N  79.1W    60 KT
 12HR VT     06/1200Z 34.9N  78.6W    50 KT...INLAND
 24HR VT     07/0000Z 39.0N  75.0W    45 KT...INLAND
 36HR VT     07/1200Z 42.5N  69.5W    40 KT...EXTRATROPICAL
 48HR VT     08/0000Z 46.5N  60.0W    40 KT...EXTRATROPICAL
 72HR VT     09/0000Z 50.0N  42.0W    40 KT...EXTRATROPICAL
 96HR VT     10/0000Z 51.5N  27.5W    45 KT...EXTRATROPICAL
120HR VT     11/0000Z 55.0N  13.0W    45 KT...EXTRATROPICAL
 
$$
FORECASTER AVILA
 

WTNT43 KNHC 060856
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  38
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT SAT SEP 06 2008
 
NATIONAL WEATHER SERVICE WSR-88D RADAR DATA...AND SURFACE
OBSERVATIONS...SHOW THAT THE CENTER OF HANNA CAME ASHORE AT ABOUT
0720 UTC NEAR THE BORDER BETWEEN SOUTH CAROLINA AND NORTH CAROLINA. 
PRIOR TO LANDFALL...AN AIR FORCE RECONNAISSANCE AIRCRAFT MEASURED A
CENTRAL PRESSURE OF 983 MB...BUT FLIGHT-LEVEL AND SFMR DATA DID NOT
REVEAL ANY INCREASE IN THE WINDS...NOR DID WSR-88D RADAR
VELOCITIES.  THE INTENSITY APPEARED TO BE 55 TO 60 KT WHILE THE
CENTER WAS STILL OVER WATER...BUT NOW THAT IT IS INLAND THE MAXIMUM
WINDS HAVE PROBABLY COME DOWN TO ABOUT 50 KT.  SLIGHT WEAKENING IS
FORECAST AS HANNA WILL BE MOVING ROUGHLY PARALLEL TO THE EAST COAST
OF THE UNITED STATES DURING THE NEXT DAY OR SO.  LITTLE CHANGE IN
STRENGTH IS ANTICIPATED THEREAFTER AS HANNA BECOMES AN
EXTRATROPICAL CYCLONE NEAR OR OVER SOUTHEASTERN CANADA.

HANNA IS ROUNDING THE MID-LEVEL RIDGE OVER THE WESTERN
ATLANTIC...TURNING RIGHT AND ACCELERATING.  THE INITIAL MOTION
ESTIMATE IS ABOUT 020/19...BUT HANNA SHOULD TURN NORTHEASTWARD
WITHIN THE NEXT 24 HOURS AS IT ENTERS THE MID-LATITUDE WESTERLIES. 
THE NEW OFFICIAL FORECAST TRACK IS ADJUSTED SLIGHTLY TO THE LEFT OF
THE PREVIOUS ONE...AND IS NOW CLOSE TO A CONSENSUS OF THE
TIGHTLY-CLUSTERED MODEL SOLUTIONS. 
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/0900Z 34.4N  78.3W    50 KT
 12HR VT     06/1800Z 37.3N  76.7W    50 KT...INLAND
 24HR VT     07/0600Z 41.2N  72.2W    45 KT...NEAR COAST
 36HR VT     07/1800Z 45.0N  64.8W    45 KT...INLAND EXTRATROPICAL
 48HR VT     08/0600Z 48.2N  56.2W    45 KT...INLAND EXTRATROPICAL
 72HR VT     09/0600Z 50.5N  38.5W    45 KT...EXTRATROPICAL
 96HR VT     10/0600Z 54.5N  20.5W    45 KT...EXTRATROPICAL
120HR VT     11/0600Z 58.5N  11.5W    45 KT...EXTRATROPICAL
 
$$
FORECASTER KNABB
 

WTNT43 KNHC 061435
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  39
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT SAT SEP 06 2008
 
THE CENTER OF HANNA IS MOVING INTO SOUTHEASTERN VIRGINA...WITH
SATELLITE IMAGERY SHOWING A CONVECTIVE OVERCAST JUST NORTH OF THE
CENTER...AND RADAR DATA SHOWING WIDESPREAD RAINBANDS OVER THE
NORTHERN SEMICIRCLE.  WHILE THERE ARE NO RECENT OBSERVATIONS OF
SUSTAINED TROPICAL STORM-FORCE WINDS...IT IS ESTIMATED THAT THE
MAXIMUM WINDS REMAIN 45 KT IN THE EASTERN SEMICIRCLE IN AREAS NOT
CURRENTLY SAMPLED.  WHILE LITTLE CHANGE IN STRENGTH IS LIKELY
THROUGH THE FORECAST PERIOD...HANNA IS EXPECTED TO LOSE TROPICAL
CHARACTERISTICS IN ABOUT 24 HOURS.

THE INITIAL MOTION IS NOW 025/22.  HANNA IS ROUNDING THE END OF THE
WESTERN ATLANTIC RIDGE AND SHOULD ACCELERATE NORTHEASTWARD INTO THE
WESTERLIES DURING THE NEXT 24-48 HR.  AFTER THAT...THE SYSTEM
SHOULD MOVE GENERALLY EAST-NORTHEASTWARD FOR THE REMAINDER OF THE
FORECAST PERIOD.  THE MODEL GUIDANCE IS TIGHTLY CLUSTERED AROUND
THIS SCENARIO...AND NEW FORECAST TRACK IS ESSENTIALLY AN UPDATE OF
THE PREVIOUS TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/1500Z 36.6N  77.4W    45 KT
 12HR VT     07/0000Z 39.7N  74.7W    45 KT...INLAND
 24HR VT     07/1200Z 43.5N  68.4W    45 KT...INLAND EXTRATROPICAL
 36HR VT     08/0000Z 46.8N  60.1W    45 KT...EXTRATROPICAL
 48HR VT     08/1200Z 49.0N  51.6W    45 KT...EXTRATROPICAL
 72HR VT     09/1200Z 51.0N  34.0W    45 KT...EXTRATROPICAL
 96HR VT     10/1200Z 55.0N  19.0W    45 KT...EXTRATROPICAL
120HR VT     11/1200Z 59.0N  10.5W    45 KT...EXTRATROPICAL
 
$$
FORECASTER BEVEN
 

WTNT43 KNHC 062032
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  40
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT SAT SEP 06 2008
 
THE CENTER OF HANNA IS MOVING OVER THE DELMARVA PENINSULA...
WITH RADAR DATA CONTINUING TO SHOW WIDESPREAD RAINBANDS OVER THE
NORTHERN SEMICIRCLE.  HOWEVER...THE CENTRAL CONVECTION IS
DECREASING...AND THE CENTRAL PRESSURE HAS RISEN TO 994 MB.
RECENT SURFACE OBSERVATIONS HAVE SHOWN 35-40 KT SUSTAINED WINDS. 
SO...THE MAXIMUM INTENSITY IS MAINTAINED AT 45 KT ON THE PREMISE
THAT THE MAXIMUM WINDS WERE NOT SAMPLED.  AS BEFORE...WHILE LITTLE
CHANGE IN STRENGTH IS LIKELY THROUGH THE FORECAST PERIOD...HANNA IS
EXPECTED TO LOSE TROPICAL CHARACTERISTICS IN 12-24 HOURS.
 
THE INITIAL MOTION IS NOW 040/23.  HANNA IS ENTERING THE WESTERLIES
AND SHOULD ACCELERATE NORTHEASTWARD FOR THE NEXT 24-36 HR..FOLLOWED
BY A RAPID EASTWARD MOTION.  A TURN TOWARD THE NORTHEAST WITH SOME
DECELERATION IS POSSIBLE AFTER 96 HR.  THE MODEL GUIDANCE IS FAIRLY
WELL CLUSTERED AROUND THIS SCENARIO...AND THE NEW FORECAST TRACK IS
ESSENTIALLY AN UPDATE OF THE PREVIOUS TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/2100Z 38.5N  75.8W    45 KT...INLAND
 12HR VT     07/0600Z 41.7N  71.8W    45 KT...INLAND
 24HR VT     07/1800Z 45.3N  64.6W    45 KT...EXTRATROPICAL
 36HR VT     08/0600Z 48.3N  56.0W    45 KT...INLAND EXTRATROPICAL
 48HR VT     08/1800Z 49.6N  47.2W    45 KT...EXTRATROPICAL
 72HR VT     09/1800Z 51.5N  31.0W    45 KT...EXTRATROPICAL
 96HR VT     10/1800Z 56.0N  17.5W    45 KT...EXTRATROPICAL
120HR VT     11/1800Z 60.0N  10.0W    45 KT...EXTRATROPICAL
 
$$
FORECASTER BEVEN
 

WTNT43 KNHC 070250
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  41
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT SAT SEP 06 2008
 
THE CENTER OF HANNA IS MOVING OVER THE WEST-CENTRAL PORTION OF LONG
ISLAND. THE INITIAL MOTION ESTIMATE IS 050/26...AND HANNA IS RIGHT
ON TRACK. GRADUAL ACCELERATION IS FORECAST DURING THE NEXT 48 HOURS
AS HANNA GETS CAUGHT UP IN THE FAST UPPER-LEVEL WESTERLIE...AND THE
NEW NHC MODEL GUIDANCE IS TIGHTLY CLUSTERED ABOUT THE PREVIOUS
FORECAST TRACK. THEREFORE...NO SIGNIFICANT CHANGES HAVE BEEN MADE
AND HANNA IS EXPECTED TO CLEAR THE U.S. COASTLINE AROUND CAPE COD
MASSACHUSETTS BY 07/0900Z.

HANNA'S FAST FORWARD MOTION HAS LIKELY CONTRIBUTED TO SOME OF
INCREASE IN OBSERVED SURFACE WINDS OBTAINED FROM SHIPS AND BUOYS
SOUTH OF LONG ISLAND. TWO UNCONFIRMED SHIP REPORTS OF 64 KT AND 60
KT HAVE BEEN RECEIVED DURING THE PAST COUPLE OF HOURS...ONE OF
WHICH OCCURRED IN A RAIN BAND. HOWEVER...THESE COULD HAVE BEEN
ISOLATED GUSTS AND THE RAIN BANDS HAVE SINCE DISSIPATED.
THEREFORE...THE INITIAL INTENSITY WILL BE 50 KT FOR THIS ADVISORY
BASED ON EARLIER DOPPLER VELOCITY VALUES OF 70 KT AT 5000 TO 7000
FT THAT COVERED A SIGNIFICANT PORTION OF THE SOUTHEASTERN QUADRANT
OF HANNA IN SEVERAL RAIN BANDS. LITTLE CHANGE IN STRENGTH IS
EXPECTED THROUGHOUT THE FORECAST PERIOD...AND HANNA COULD EASILY BE
AN EXTRATROPICAL STORM WITH 50-KT SUSTAINED WINDS AT ANY OF THE
FORECAST TIMES.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      07/0300Z 40.5N  73.4W    50 KT...BECOMING EXTRATROPICAL
 12HR VT     07/1200Z 43.0N  68.8W    50 KT...EXTRATROPICAL
 24HR VT     08/0000Z 46.4N  61.1W    45 KT...EXTRATROPICAL
 36HR VT     08/1200Z 48.8N  53.2W    45 KT...EXTRATROPICAL
 48HR VT     09/0000Z 50.0N  45.0W    45 KT...EXTRATROPICAL
 72HR VT     10/0000Z 52.5N  28.3W    45 KT...EXTRATROPICAL
 96HR VT     11/0000Z 56.5N  15.5W    45 KT...EXTRATROPICAL
120HR VT     12/0000Z 61.5N  11.5W    45 KT...EXTRATROPICAL
 
$$
FORECASTER STEWART
 

WTNT43 KNHC 070857
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  42
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT SUN SEP 07 2008
 
THE CLOUD PATTERN ASSOCIATED WITH HANNA IS SPREADING OUT WELL AHEAD
OF THE SURFACE CENTER...WITH THE CLOSEST DEEP CONVECTION NOW
DISPLACED ABOUT 125 NMI TO THE NORTH AND NORTHEAST.  THE
CIRCULATION IS ALSO CLOSE TO...BUT NOT QUITE ENTANGLED WITH...A
FRONTAL BOUNDARY.  BASED ON THE LOSS OF CONVECTION NEAR THE
CORE...HANNA IS NO LONGER CONSIDERED TO BE A TROPICAL CYCLONE AND
THIS WILL BE THE LAST ADVISORY.

MAXIMUM WINDS ARE ESTIMATED TO BE 45 KT BASED ON SHIP REPORTS...AND
HANNA IS EXPECTED TO REMAIN A VIGOROUS EXTRATROPICAL CYCLONE DURING
ITS PASSAGE OVER THE NORTH ATLANTIC.  THE OFFICIAL FORECAST IS IN
GOOD AGREEMENT WITH THE GFS.
 
FUTURE INFORMATION ON THIS SYSTEM CAN BE FOUND IN HIGH SEAS
FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE OCEAN PREDICTION
CENTER...UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      07/0900Z 42.6N  70.0W    45 KT...EXTRATROPICAL
 12HR VT     07/1800Z 45.4N  64.5W    45 KT...EXTRATROPICAL
 24HR VT     08/0600Z 48.4N  57.1W    45 KT...EXTRATROPICAL
 36HR VT     08/1800Z 50.0N  50.0W    45 KT...EXTRATROPICAL
 48HR VT     09/0600Z 51.0N  43.0W    45 KT...EXTRATROPICAL
 72HR VT     10/0600Z 53.5N  27.0W    45 KT...EXTRATROPICAL
 96HR VT     11/0600Z 58.0N  16.0W    40 KT...EXTRATROPICAL
120HR VT     12/0600Z...ABSORBED WITHIN EXTRATROPICAL LOW
 
$$
FORECASTER FRANKLIN
 

WTNT43 KNHC 052038
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  36
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT FRI SEP 05 2008

REPORTS FROM AN AIR FORCE RESERVE HURRICANE HURRICANE HUNTER
AIRCRAFT INDICATE THAT HANNA IS JUST BELOW HURRICANE STRENGTH.  THE
STEPPED FREQUENCY MICROWAVE REPORTED TWO AREAS OF WIND OF ABOUT 65
KT.  HOWEVER...DROPSONDE DATA SUGGESTS THAT THE SFMR ESTIMATES WERE
A LITTLE TOO HIGH.  THE MAXIMUM 850 MB FLIGHT-LEVEL WINDS WERE 75
KT ABOUT 75 N MI EAST OF THE CENTER.  THE LAST REPORTED CENTRAL
PRESSURE WAS 984 MB...UP A LITTLE FROM THIS MORNING.  BASED ON ALL
THIS...THE INITIAL INTENSITY IS SET AT 60 KT.  IT SHOULD BE NOTED
THAT THERE IS NOT MUCH DIFFERENCE METEOROLOGICALLY BETWEEN A 60-KT
TROPICAL STORM AND A 65-KT HURRICANE.

THE MOTION IS A SOMEWHAT WOBBLY 360/17...WITH A RE-ANALYSIS OF
AIRCRAFT DATA SUGGESTING THIS MOTION BEGAN JUST AFTER THE 11Z
AIRCRAFT FIX.  HANNA IS MOVING AROUND THE WESTERN END OF THE
SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC AND SHOULD ENTER THE
WESTERLIES IN 24-36 HR.  THIS SHOULD RESULT IN RECURVATURE TO THE
NORTHEAST AND ACCELERATION.  ALL GUIDANCE AGREES WITH THIS
SCENARIO...AND THERE ARE NO SIGNIFICANT OUTLIERS AMONGST THE
DYNAMICAL MODELS.  THE NEW FORECAST TRACK IS ADJUSTED A LITTLE TO
THE RIGHT OF THE PREVIOUS TRACK AND LIES DOWN THE MIDDLE OF THE
GUIDANCE ENVELOPE.

VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT ARE STILL ISSUES FOR
HANNA...AND SIGNIFICANT STRENGTHENING APPEARS UNLIKELY BEFORE
LANDFALL.  HOWEVER...THERE IS A POSSIBILITY THAT A CONVECTIVE BURST
COULD CAUSE THE STORM TO REACH HURRICANE STRENGTH.  THE CYCLONE
SHOULD WEAKEN AFTER LANDFALL AND BECOME EXTRATROPICAL IN ABOUT 36
HR.  THE GFS AND UKMET CONTINUE TO SUGGEST THE POSSIBILITY OF
DEEPENING AS AN EXTRATROPICAL SYSTEM LATE IN THE FORECAST
PERIOD...AND THIS IS REFLECTED IN THE 96 AND 120 HR FORECASTS.

FORECAST POSITIONS AND MAX WINDS

INITIAL      05/2100Z 30.8N  78.7W    60 KT
12HR VT     06/0600Z 33.2N  78.5W    60 KT
24HR VT     06/1800Z 36.7N  76.8W    50 KT...INLAND
36HR VT     07/0600Z 40.7N  72.4W    45 KT...EXTRATROPICAL
48HR VT     07/1800Z 44.5N  65.6W    40 KT...INLAND EXTRATROPICAL
72HR VT     08/1800Z 50.0N  47.5W    40 KT...EXTRATROPICAL
96HR VT     09/1800Z 51.0N  30.0W    45 KT...EXTRATROPICAL
120HR VT     10/1800Z 52.5N  14.0W    45 KT...EXTRATROPICAL

$$
FORECASTER BEVEN



000

WTNT43 KNHC 060255
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  37
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT FRI SEP 05 2008

DATA FROM A RECONNAISSACE PLANE INDICATE THAT THE SURFACE PRESSURE
HAS DROPPED TO 978 MB BUT WINDS HAVE NOT INCREASED. INITIAL
INTENSITY IS KEPT AT 60 KNOTS. THE AREA OF STRONG WINDS HAS BEEN
SHRINKING SINCE HANNA APPEARS TO BE MORE TROPICAL AND THERE IS A
PERSISTENT AND LARGE AREA OF DEEP CONVECTION NEAR THE CENTER. HANNA
COULD REACH THE COAST IN LESS THAN 12 HOURS AS A HURRICANE SINCE IT
ONLY NEEDS FIVE KNOTS TO BE ONE. HOWEVER...THERE IS NOT MUCH
DIFFERENCE BETWEEN A 60-KT TROPICAL STORM AND A 65-KT HURRICANE.

RADAR AND RECONNAISSANCE FIXES INDICATE THAT HANNA IS MOVING
NORTHWARD AT 17 KNOTS. THE CYCLONE IS ALREADY EMBEDDED IN A STRONG
SOUTHERLY AND SOUTHWESTERLY FLOW...AND SOON HANNA SHOULD BEGIN TO
TURN TO THE NORTHEAST WITH AN INCREASE IN FORWARD SPEED. AFTER
LANDFALL...AS HANNA BECOMES FULLY INVOLVED WITH THE MID-LATITUDE
FLOW...IT SHOULD BECOME EXTRATROPICAL IN ABOUT 24 TO 36 HOURS.
DURING THIS PERIOD...HANNA WILL BE MOVING VERY CLOSE TO OR OVER THE
NORTHEAST COAST OF THE UNITED STATES.


FORECAST POSITIONS AND MAX WINDS

INITIAL      06/0300Z 32.4N  79.1W    60 KT
12HR VT     06/1200Z 34.9N  78.6W    50 KT...INLAND
24HR VT     07/0000Z 39.0N  75.0W    45 KT...INLAND
36HR VT     07/1200Z 42.5N  69.5W    40 KT...EXTRATROPICAL
48HR VT     08/0000Z 46.5N  60.0W    40 KT...EXTRATROPICAL
72HR VT     09/0000Z 50.0N  42.0W    40 KT...EXTRATROPICAL
96HR VT     10/0000Z 51.5N  27.5W    45 KT...EXTRATROPICAL
120HR VT     11/0000Z 55.0N  13.0W    45 KT...EXTRATROPICAL

$$
FORECASTER AVILA



000

WTNT43 KNHC 060856
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  38
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT SAT SEP 06 2008

NATIONAL WEATHER SERVICE WSR-88D RADAR DATA...AND SURFACE
OBSERVATIONS...SHOW THAT THE CENTER OF HANNA CAME ASHORE AT ABOUT
0720 UTC NEAR THE BORDER BETWEEN SOUTH CAROLINA AND NORTH CAROLINA.
PRIOR TO LANDFALL...AN AIR FORCE RECONNAISSANCE AIRCRAFT MEASURED A
CENTRAL PRESSURE OF 983 MB...BUT FLIGHT-LEVEL AND SFMR DATA DID NOT
REVEAL ANY INCREASE IN THE WINDS...NOR DID WSR-88D RADAR
VELOCITIES.  THE INTENSITY APPEARED TO BE 55 TO 60 KT WHILE THE
CENTER WAS STILL OVER WATER...BUT NOW THAT IT IS INLAND THE MAXIMUM
WINDS HAVE PROBABLY COME DOWN TO ABOUT 50 KT.  SLIGHT WEAKENING IS
FORECAST AS HANNA WILL BE MOVING ROUGHLY PARALLEL TO THE EAST COAST
OF THE UNITED STATES DURING THE NEXT DAY OR SO.  LITTLE CHANGE IN
STRENGTH IS ANTICIPATED THEREAFTER AS HANNA BECOMES AN
EXTRATROPICAL CYCLONE NEAR OR OVER SOUTHEASTERN CANADA.

HANNA IS ROUNDING THE MID-LEVEL RIDGE OVER THE WESTERN
ATLANTIC...TURNING RIGHT AND ACCELERATING.  THE INITIAL MOTION
ESTIMATE IS ABOUT 020/19...BUT HANNA SHOULD TURN NORTHEASTWARD
WITHIN THE NEXT 24 HOURS AS IT ENTERS THE MID-LATITUDE WESTERLIES.
THE NEW OFFICIAL FORECAST TRACK IS ADJUSTED SLIGHTLY TO THE LEFT OF
THE PREVIOUS ONE...AND IS NOW CLOSE TO A CONSENSUS OF THE
TIGHTLY-CLUSTERED MODEL SOLUTIONS.



FORECAST POSITIONS AND MAX WINDS

INITIAL      06/0900Z 34.4N  78.3W    50 KT
12HR VT     06/1800Z 37.3N  76.7W    50 KT...INLAND
24HR VT     07/0600Z 41.2N  72.2W    45 KT...NEAR COAST
36HR VT     07/1800Z 45.0N  64.8W    45 KT...INLAND EXTRATROPICAL
48HR VT     08/0600Z 48.2N  56.2W    45 KT...INLAND EXTRATROPICAL
72HR VT     09/0600Z 50.5N  38.5W    45 KT...EXTRATROPICAL
96HR VT     10/0600Z 54.5N  20.5W    45 KT...EXTRATROPICAL
120HR VT     11/0600Z 58.5N  11.5W    45 KT...EXTRATROPICAL

$$
FORECASTER KNABB




WTNT43 KNHC 061435
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  39
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 AM EDT SAT SEP 06 2008

THE CENTER OF HANNA IS MOVING INTO SOUTHEASTERN VIRGINA...WITH
SATELLITE IMAGERY SHOWING A CONVECTIVE OVERCAST JUST NORTH OF THE
CENTER...AND RADAR DATA SHOWING WIDESPREAD RAINBANDS OVER THE
NORTHERN SEMICIRCLE.  WHILE THERE ARE NO RECENT OBSERVATIONS OF
SUSTAINED TROPICAL STORM-FORCE WINDS...IT IS ESTIMATED THAT THE
MAXIMUM WINDS REMAIN 45 KT IN THE EASTERN SEMICIRCLE IN AREAS NOT
CURRENTLY SAMPLED.  WHILE LITTLE CHANGE IN STRENGTH IS LIKELY
THROUGH THE FORECAST PERIOD...HANNA IS EXPECTED TO LOSE TROPICAL
CHARACTERISTICS IN ABOUT 24 HOURS.

THE INITIAL MOTION IS NOW 025/22.  HANNA IS ROUNDING THE END OF THE
WESTERN ATLANTIC RIDGE AND SHOULD ACCELERATE NORTHEASTWARD INTO THE
WESTERLIES DURING THE NEXT 24-48 HR.  AFTER THAT...THE SYSTEM
SHOULD MOVE GENERALLY EAST-NORTHEASTWARD FOR THE REMAINDER OF THE
FORECAST PERIOD.  THE MODEL GUIDANCE IS TIGHTLY CLUSTERED AROUND
THIS SCENARIO...AND NEW FORECAST TRACK IS ESSENTIALLY AN UPDATE OF
THE PREVIOUS TRACK.

FORECAST POSITIONS AND MAX WINDS

INITIAL      06/1500Z 36.6N  77.4W    45 KT
12HR VT     07/0000Z 39.7N  74.7W    45 KT...INLAND
24HR VT     07/1200Z 43.5N  68.4W    45 KT...INLAND EXTRATROPICAL
36HR VT     08/0000Z 46.8N  60.1W    45 KT...EXTRATROPICAL
48HR VT     08/1200Z 49.0N  51.6W    45 KT...EXTRATROPICAL
72HR VT     09/1200Z 51.0N  34.0W    45 KT...EXTRATROPICAL
96HR VT     10/1200Z 55.0N  19.0W    45 KT...EXTRATROPICAL
120HR VT     11/1200Z 59.0N  10.5W    45 KT...EXTRATROPICAL

$$
FORECASTER BEVEN



000

WTNT43 KNHC 062032
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  40
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 PM EDT SAT SEP 06 2008

THE CENTER OF HANNA IS MOVING OVER THE DELMARVA PENINSULA...
WITH RADAR DATA CONTINUING TO SHOW WIDESPREAD RAINBANDS OVER THE
NORTHERN SEMICIRCLE.  HOWEVER...THE CENTRAL CONVECTION IS
DECREASING...AND THE CENTRAL PRESSURE HAS RISEN TO 994 MB.
RECENT SURFACE OBSERVATIONS HAVE SHOWN 35-40 KT SUSTAINED WINDS.
SO...THE MAXIMUM INTENSITY IS MAINTAINED AT 45 KT ON THE PREMISE
THAT THE MAXIMUM WINDS WERE NOT SAMPLED.  AS BEFORE...WHILE LITTLE
CHANGE IN STRENGTH IS LIKELY THROUGH THE FORECAST PERIOD...HANNA IS
EXPECTED TO LOSE TROPICAL CHARACTERISTICS IN 12-24 HOURS.

THE INITIAL MOTION IS NOW 040/23.  HANNA IS ENTERING THE WESTERLIES
AND SHOULD ACCELERATE NORTHEASTWARD FOR THE NEXT 24-36 HR..FOLLOWED
BY A RAPID EASTWARD MOTION.  A TURN TOWARD THE NORTHEAST WITH SOME
DECELERATION IS POSSIBLE AFTER 96 HR.  THE MODEL GUIDANCE IS FAIRLY
WELL CLUSTERED AROUND THIS SCENARIO...AND THE NEW FORECAST TRACK IS
ESSENTIALLY AN UPDATE OF THE PREVIOUS TRACK.

FORECAST POSITIONS AND MAX WINDS

INITIAL      06/2100Z 38.5N  75.8W    45 KT...INLAND
12HR VT     07/0600Z 41.7N  71.8W    45 KT...INLAND
24HR VT     07/1800Z 45.3N  64.6W    45 KT...EXTRATROPICAL
36HR VT     08/0600Z 48.3N  56.0W    45 KT...INLAND EXTRATROPICAL
48HR VT     08/1800Z 49.6N  47.2W    45 KT...EXTRATROPICAL
72HR VT     09/1800Z 51.5N  31.0W    45 KT...EXTRATROPICAL
96HR VT     10/1800Z 56.0N  17.5W    45 KT...EXTRATROPICAL
120HR VT     11/1800Z 60.0N  10.0W    45 KT...EXTRATROPICAL

$$
FORECASTER BEVEN



000

WTNT43 KNHC 070250
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  41
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
1100 PM EDT SAT SEP 06 2008

THE CENTER OF HANNA IS MOVING OVER THE WEST-CENTRAL PORTION OF LONG
ISLAND. THE INITIAL MOTION ESTIMATE IS 050/26...AND HANNA IS RIGHT
ON TRACK. GRADUAL ACCELERATION IS FORECAST DURING THE NEXT 48 HOURS
AS HANNA GETS CAUGHT UP IN THE FAST UPPER-LEVEL WESTERLIE...AND THE
NEW NHC MODEL GUIDANCE IS TIGHTLY CLUSTERED ABOUT THE PREVIOUS
FORECAST TRACK. THEREFORE...NO SIGNIFICANT CHANGES HAVE BEEN MADE
AND HANNA IS EXPECTED TO CLEAR THE U.S. COASTLINE AROUND CAPE COD
MASSACHUSETTS BY 07/0900Z.

HANNA'S FAST FORWARD MOTION HAS LIKELY CONTRIBUTED TO SOME OF
INCREASE IN OBSERVED SURFACE WINDS OBTAINED FROM SHIPS AND BUOYS
SOUTH OF LONG ISLAND. TWO UNCONFIRMED SHIP REPORTS OF 64 KT AND 60
KT HAVE BEEN RECEIVED DURING THE PAST COUPLE OF HOURS...ONE OF
WHICH OCCURRED IN A RAIN BAND. HOWEVER...THESE COULD HAVE BEEN
ISOLATED GUSTS AND THE RAIN BANDS HAVE SINCE DISSIPATED.
THEREFORE...THE INITIAL INTENSITY WILL BE 50 KT FOR THIS ADVISORY
BASED ON EARLIER DOPPLER VELOCITY VALUES OF 70 KT AT 5000 TO 7000
FT THAT COVERED A SIGNIFICANT PORTION OF THE SOUTHEASTERN QUADRANT
OF HANNA IN SEVERAL RAIN BANDS. LITTLE CHANGE IN STRENGTH IS
EXPECTED THROUGHOUT THE FORECAST PERIOD...AND HANNA COULD EASILY BE
AN EXTRATROPICAL STORM WITH 50-KT SUSTAINED WINDS AT ANY OF THE
FORECAST TIMES.

FORECAST POSITIONS AND MAX WINDS

INITIAL      07/0300Z 40.5N  73.4W    50 KT...BECOMING EXTRATROPICAL
12HR VT     07/1200Z 43.0N  68.8W    50 KT...EXTRATROPICAL
24HR VT     08/0000Z 46.4N  61.1W    45 KT...EXTRATROPICAL
36HR VT     08/1200Z 48.8N  53.2W    45 KT...EXTRATROPICAL
48HR VT     09/0000Z 50.0N  45.0W    45 KT...EXTRATROPICAL
72HR VT     10/0000Z 52.5N  28.3W    45 KT...EXTRATROPICAL
96HR VT     11/0000Z 56.5N  15.5W    45 KT...EXTRATROPICAL
120HR VT     12/0000Z 61.5N  11.5W    45 KT...EXTRATROPICAL

$$
FORECASTER STEWART




WTNT43 KNHC 070857
TCDAT3
TROPICAL STORM HANNA DISCUSSION NUMBER  42
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL082008
500 AM EDT SUN SEP 07 2008

THE CLOUD PATTERN ASSOCIATED WITH HANNA IS SPREADING OUT WELL AHEAD
OF THE SURFACE CENTER...WITH THE CLOSEST DEEP CONVECTION NOW
DISPLACED ABOUT 125 NMI TO THE NORTH AND NORTHEAST.  THE
CIRCULATION IS ALSO CLOSE TO...BUT NOT QUITE ENTANGLED WITH...A
FRONTAL BOUNDARY.  BASED ON THE LOSS OF CONVECTION NEAR THE
CORE...HANNA IS NO LONGER CONSIDERED TO BE A TROPICAL CYCLONE AND
THIS WILL BE THE LAST ADVISORY.

MAXIMUM WINDS ARE ESTIMATED TO BE 45 KT BASED ON SHIP REPORTS...AND
HANNA IS EXPECTED TO REMAIN A VIGOROUS EXTRATROPICAL CYCLONE DURING
ITS PASSAGE OVER THE NORTH ATLANTIC.  THE OFFICIAL FORECAST IS IN
GOOD AGREEMENT WITH THE GFS.

FUTURE INFORMATION ON THIS SYSTEM CAN BE FOUND IN HIGH SEAS
FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE OCEAN PREDICTION
CENTER...UNDER AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC.


FORECAST POSITIONS AND MAX WINDS

INITIAL      07/0900Z 42.6N  70.0W    45 KT...EXTRATROPICAL
12HR VT     07/1800Z 45.4N  64.5W    45 KT...EXTRATROPICAL
24HR VT     08/0600Z 48.4N  57.1W    45 KT...EXTRATROPICAL
36HR VT     08/1800Z 50.0N  50.0W    45 KT...EXTRATROPICAL
48HR VT     09/0600Z 51.0N  43.0W    45 KT...EXTRATROPICAL
72HR VT     10/0600Z 53.5N  27.0W    45 KT...EXTRATROPICAL
96HR VT     11/0600Z 58.0N  16.0W    40 KT...EXTRATROPICAL
120HR VT     12/0600Z...ABSORBED WITHIN EXTRATROPICAL LOW

$$
FORECASTER FRANKLIN




