WTNT42 KNHC 111010
TCDAT2
TROPICAL DEPRESSION TWO SPECIAL DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
600 AM AST TUE AUG 11 2009
 
FIRST LIGHT VISIBLE SATELLITE IMAGES SHOW THAT THE BROAD LOW
PRESSURE AREA ASSOCIATED WITH A TROPICAL WAVE THAT WE HAVE BEEN
TRACKING OVER THE FAR EASTERN TROPICAL ATLANTIC HAS ACQUIRED
SUFFICENT ORGANIZED DEEP CONVECTION TO BE DESIGNATED AS A TROPICAL
DEPRESSION.  THE TROPICAL CYCLONE IS SITUATED OVER MARGINALLY WARM
SEA SURFACE TEMPERATURES AND THE VERTICAL SHEAR IS CURRENTLY RATHER
WEAK.  THE OFFICIAL FORECAST SHOWS GRADUAL STRENGHENING OVER THE
NEXT COUPLE OF DAYS AND IS A BLEND OF THE VARIOUS NUMERICAL
GUIDANCE TOOLS.  AS USUAL THERE IS CONSIDERABLE UNCERTAINTY AS TO
THE STRENGTH OF THIS SYSTEM LATER IN THE FORECAST PERIOD.  IF THE
CYCLONE MOVES FARTHER NORTH THAN ANTICIPATED BELOW IT WILL PROBABLY
ENCOUNTER STRONGER SHEAR AND NOT INTENSIFY AS MUCH AS FORECAST.  ON
THE OTHER HAND IF THE SYSTEM MOVES FARTHER SOUTH THAN EXPECTED LATE
IN THE PERIOD...IT WILL PROBABLY BECOME STRONGER THAN ANTICIPATED
HERE.

INITIAL MOTION IS ABOUT 270/11.  THIS TRACK IS LIKELY TO MORE OR
LESS CONTINUE FOR THE NEXT 2-3 DAYS DUE TO THE FLOW SOUTH OF A
FAIRLY WELL-ESTABLISHED MID-LEVEL SUBTROPICAL RIDGE.  LATER IN THE
PERIOD...A SLIGHT WEAKNESS IN THE RIDGE IS LIKELY TO INDUCE A MORE
WEST-NORTHWESTWARD MOTION.  THE OFFICIAL FORECAST IS A LITTLE
SLOWER THAN THE MODEL CONSENSUS AND WELL TO THE SOUTH AND WEST OF
THE BAM TRACKS.  THIS IS ALSO SOUTH OF THE LATEST HWRF TRACK.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/1000Z 14.4N  28.6W    25 KT
 12HR VT     11/1800Z 14.6N  30.1W    30 KT
 24HR VT     12/0600Z 14.8N  32.3W    35 KT
 36HR VT     12/1800Z 15.0N  34.6W    35 KT
 48HR VT     13/0600Z 15.2N  36.8W    40 KT
 72HR VT     14/0600Z 16.0N  41.2W    45 KT
 96HR VT     15/0600Z 17.5N  45.5W    50 KT
120HR VT     16/0600Z 19.5N  49.5W    50 KT
 
$$
FORECASTER PASCH
 

WTNT42 KNHC 111445
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 AM AST TUE AUG 11 2009
 
THE DEPRESSION IS A LITTLE THIN ON DEEP CONVECTION AT THE
MOMENT...BUT IT STILL HAS A SMALL WELL-DEFINED LOW-LEVEL
CIRCULATION.  AN 1114 UTC ASCAT PASS INDICATED THAT MAXIMUM WINDS
ARE 25 KT...LIMITED TO THE WESTERN SIDE OF THE CIRCULATION...AND
THE INITIAL INTENSITY IS HELD AT THAT INTENSITY FOR THIS ADVISORY. 
IN GENERAL...THE NUMERICAL GUIDANCE IS NOT ALL THAT AGGRESSIVE IN
SHOWING INTENSIFICATION OF THIS SYSTEM.  SEA SURFACE TEMPERATURES
ALONG THE FORECAST TRACK WILL BE MARGINALLY WARM...AND THE
DEPRESSION WILL HAVE TO ENDURE SOME DRY AIR IN THE MID-LEVELS. 
NONETHELESS...VERTICAL SHEAR IS EXPECTED TO BE LIGHT ENOUGH DURING
THE FIRST FOUR DAYS OR SO TO ALLOW SOME SLOW STRENGTHENING.  THE
SYSTEM COULD MOVE FAR ENOUGH NORTH BY DAY 5 THAT IT BEGINS TO FEEL
THE EFFECTS OF UPPER-LEVEL WESTERLY WINDS...AND THE OFFICIAL
FORECAST INDICATES SOME WEAKENING BY THEN.  IT MUST BE STATED AGAIN
THAT IF THE DEPRESSION TAKES A MORE SOUTHERN TRACK...IT WOULD STAY
AWAY FROM THE INCREASING SHEAR AND COULD POSSIBLY BECOME STRONGER
THAN INDICATED HERE.

THE DEPRESSION IS MOVING AT 275/11.  LITTLE CHANGE TO THIS MOTION IS
EXPECTED OVER THE NEXT 3 DAYS DUE TO A MID-LEVEL SUBTROPICAL RIDGE
FORECAST TO PERSIST NORTH OF THE DEPRESSION.  BY DAYS 4 AND 5...A
WEAKNESS IS EXPECTED TO DEVELOP IN THE RIDGE OVER THE CENTRAL
ATLANTIC AND CAUSE THE SYSTEM TO TURN SLIGHTLY TO THE WEST-
NORTHWEST.  THE NEW OFFICIAL FORECAST IS SHIFTED A LITTLE TO THE
SOUTH BUT STILL LIES NORTH AND EAST OF THE GFDL...HWRF...AND THE
MODEL CONSENSUS TVCN.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/1500Z 14.6N  29.6W    25 KT
 12HR VT     12/0000Z 14.7N  31.3W    30 KT
 24HR VT     12/1200Z 14.8N  33.6W    35 KT
 36HR VT     13/0000Z 14.9N  35.8W    35 KT
 48HR VT     13/1200Z 15.1N  38.2W    40 KT
 72HR VT     14/1200Z 16.0N  43.0W    45 KT
 96HR VT     15/1200Z 17.5N  47.5W    50 KT
120HR VT     16/1200Z 20.0N  52.0W    45 KT
 
$$
FORECASTER BERG
 

WTNT42 KNHC 112040
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 PM AST TUE AUG 11 2009
 
THE DEPRESSION IS HAVING SOME TROUBLE DEVELOPING WELL-DEFINED
CONVECTIVE BANDING...AND THE DEEP CONVECTION THAT DOES EXIST IS
LIMITED TO THE WESTERN SEMICIRCLE.  THERE HAS BEEN NO IMPROVEMENT
TO THE CONVECTIVE STRUCTURE SINCE THIS MORNING...AND DVORAK FINAL
T-NUMBERS ARE T1.5 FROM BOTH TAFB AND SAB.  THIS SUPPORTS KEEPING
THE INITIAL INTENSITY AT 25 KT.  

THIS FORECAST PACKAGE MAKES NO CHANGES TO THE INTENSITY FORECAST. 
THE DEPRESSION WILL BE TRAVERSING MARGINALLY WARM WATER AND BE
UNDER LIGHT SHEAR CONDITIONS DURING THE NEXT 3 TO 4 DAYS...ALTHOUGH
THE AMBIENT MID-LEVEL ENVIRONMENT IS EXPECTED TO REMAIN DRY AND
STABLE.  SLOW STRENGTHENING IS STILL INDICATED IN THE OFFICIAL
FORECAST...PEAKING NEAR 50 KT IN ABOUT 4 DAYS.  THEREAFTER...THE
DEPRESSION IS EXPECTED TO REACH LATITUDES WHERE IT WILL BECOME
IMPACTED BY STRONGER UPPER-LEVEL WESTERLY WINDS...AND SOME
WEAKENING IS SHOWN AT THE END OF THE FORECAST PERIOD.

THE CENTER OF THE DEPRESSION IS A LITTLE DIFFICULT TO LOCATE...BUT
IT APPEARS TO BE MOVING AT AN AVERAGE MOTION OF 275/10 AS IT IS
STEERED BY THE LOW- TO MID-LEVEL FLOW SOUTH OF THE SUBTROPICAL
RIDGE.  INTERESTINGLY...THE GFS...UKMET...AND CANADIAN MODELS ALL
SHOW A WEST-SOUTHWESTWARD MOTION OCCURRING FOR THE NEXT 48 HOURS OR
SO...SO THE OFFICIAL FORECAST INDICATES THAT THE DEPRESSION WILL
MOVE DUE WEST OVER THE NEXT 24 HOURS.  THEREAFTER...THE MODELS ALL
INDICATE A WEST-NORTHWESTWARD TURN AS A WEAKNESS DEVELOPS IN THE
RIDGE...BUT THE BULK OF THEM LIE SOUTH OF THE PREVIOUS FORECAST. 
THE NEW FORECAST IS THEREFORE SHIFTED JUST A LITTLE TO THE WEST ON
DAYS 4 AND 5.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      11/2100Z 14.6N  30.4W    25 KT
 12HR VT     12/0600Z 14.7N  32.0W    30 KT
 24HR VT     12/1800Z 14.7N  34.3W    35 KT
 36HR VT     13/0600Z 14.8N  36.7W    35 KT
 48HR VT     13/1800Z 15.0N  39.1W    40 KT
 72HR VT     14/1800Z 16.0N  44.0W    45 KT
 96HR VT     15/1800Z 18.0N  49.0W    50 KT
120HR VT     16/1800Z 21.0N  54.5W    45 KT
 
$$
FORECASTER BERG
 

WTNT42 KNHC 120300
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 PM AST TUE AUG 11 2009
 
CONVENTIONAL SATELLITE IMAGERY INDICATES A RECENT BURST OF DEEP
CONVECTION OVER THE WESTERN SEMICIRCLE OF THE DEPRESSION...WITH THE
CENTER ON THE EASTERN EDGE OF THIS CONVECTIVE MASS.  EVEN THOUGH
DVORAK T-NUMBERS ARE 1.5 FROM BOTH TAFB AND SAB...A RECENTLY-
RECEIVED ASCAT PASS FROM 0000 UTC SUPPORTS INCREASING THE INTENSITY
TO 30 KT.  EVEN MORE RECENTLY...LATEST SATELLITE IMAGERY SUGGESTS A
FURTHER INCREASE IN ORGANIZATION AND THE DEPRESSION MAY NOW BE
CLOSE TO TROPICAL STORM STRENGTH.
 
WHILE THE CIRCULATION CENTER IS GRADUALLY BECOMING BETTER-
DEFINED...THERE STILL EXISTS SOME UNCERTAINTY IN THE INITIAL
LOCATION.  THE INITIAL MOTION IS ESTIMATED TO BE 275/11...AS THE
CYCLONE IS BEING STEERED BY DEEP-LAYER EASTERLY FLOW ON THE
SOUTHERN PERIPHERY OF A MID-LEVEL SUBTROPICAL RIDGE.  THIS PATTERN
SHOULD FAVOR A GENERAL WEST TO WEST-NORTHWEST COURSE OVER THE NEXT
SEVERAL DAYS...CONSISTENT WITH THE LATEST MODEL GUIDANCE.  A
WEAKNESS IN THE SUBTROPICAL RIDGE ON DAYS 4 AND 5 SHOULD ALLOW THE
CYCLONE TO BEGIN GAINING MORE LATITUDE WITH AN INCREASE IN FORWARD
SPEED.  THE HWRF SOLUTION APPEARS TO BE AN OUTLIER AMONGST THE
MODEL SUITE...IMMEDIATELY TAKING THE CYCLONE ON A MORE
NORTHWESTWARD PATH.  ON THE OTHER HAND...THE SPREAD OF THE
REMAINING GUIDANCE IS RELATIVELY SMALL...EVEN IN THE LONGER
RANGE...WHICH ADDS SOME CONFIDENCE TO THE CURRENT FORECAST.  THE
OFFICIAL FORECAST DISCOUNTS THE HWRF SOLUTION AND LIES BETWEEN THE
MODEL CONSENSUS AND THE PREVIOUS ADVISORY.
 
THE DEPRESSION IS CURRENTLY EMBEDDED IN A LOW SHEAR ENVIRONMENT WITH
MARGINAL SEA SURFACE TEMPERATURES...WHICH SHOULD SUPPORT
INTENSIFICATION.  HOWEVER...SHIPS MODEL GUIDANCE INDICATES MODEST
EASTERLY SHEAR IMPACTING THE CYCLONE SHORTLY THEREAFTER AS A RESULT
OF INCREASING MID-LEVEL HEIGHTS TO THE NORTH.  THIS INCREASE IN
SHEAR SHOULD INHIBIT FURTHER DEVELOPMENT IN THE SHORT-TERM.  LATER
IN THE PERIOD...GLOBAL MODELS SUGGEST THAT THE CYCLONE WILL
INTERACT WITH INCREASING SOUTHWESTERLY FLOW ALOFT...DOWNSTREAM OF A
PRONOUNCED MID- TO UPPER-LEVEL CYCLONE WITHIN THE MID-OCEANIC
TROUGH.  THIS INTERACTION SHOULD INDUCE SUFFICIENT SHEAR TO WEAKEN
THE SYSTEM BEGINNING DAY 4.  SHOULD THE CYCLONE TAKE A MORE
NORTHERLY TRACK...IT WOULD ENCOUNTER AN EVEN MORE HOSTILE
ENVIRONMENT WHICH COULD ACCELERATE THE WEAKENING TREND.  THEN
AGAIN...SHOULD THE CYCLONE MAINTAIN A MORE SOUTHERN TRACK...THE
SHEAR WOULD LIKELY BE LOWER WHICH WOULD SUPPORT A STRONGER SYSTEM.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      12/0300Z 14.8N  31.5W    30 KT
 12HR VT     12/1200Z 14.8N  33.2W    35 KT
 24HR VT     13/0000Z 14.8N  35.4W    35 KT
 36HR VT     13/1200Z 14.9N  37.7W    35 KT
 48HR VT     14/0000Z 15.2N  40.2W    40 KT
 72HR VT     15/0000Z 16.5N  45.0W    45 KT
 96HR VT     16/0000Z 19.0N  51.0W    45 KT
120HR VT     17/0000Z 22.0N  56.5W    40 KT
 
$$
FORECASTER KIMBERLAIN/BROWN/COHEN
 

WTNT42 KNHC 120835
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 AM AST WED AUG 12 2009
 
SATELLITE IMAGES INDICATE THAT A PERSISTENT CLUSTER OF THUNDERSTORMS
REMAINS IN THE WESTERN SEMICIRCLE OF THE DEPRESSION...ALTHOUGH
RECENTLY THIS CLUSTER HAS TAKEN ON A SOMEWHAT ELONGATED APPEARANCE. 
MICROWAVE AND SHORTWAVE INFRARED DATA SUGGEST THE CENTER REMAINS ON
THE EASTERN SIDE OF THE CONVECTION AND NOT WELL-EMBEDDED WITHIN THE
MAIN CONVECTIVE CLUSTER.  DVORAK ESTIMATES SUGGEST THE MAXIMUM
WINDS ARE NEAR 30 KT...AND THE INITIAL INTENSITY WILL BE HELD AT
THAT VALUE.
 
THERE IS CONSIDERABLE UNCERTAINTY WITH THE INITIAL POSITION...AND
THE BEST GUESS OF INITIAL MOTION IS 270/10.  GLOBAL MODELS SUGGEST A
GENERAL WESTERLY COURSE IS LIKELY FOR THE NEXT COUPLE OF DAYS AS
RIDGING BUILDS TO THE NORTH OF THE DEPRESSION.  THEREAFTER...A
WEAKNESS IN THE SUBTROPICAL HIGH OVER THE CENTRAL ATLANTIC OCEAN
COULD CAUSE THE TROPICAL CYCLONE TO GAIN SOME LATITUDE.  ALTHOUGH
THE HWRF/BAMD MODELS SHOW A SHARP NORTHWESTWARD MOTION IN THE
LATTER HALF OF THE FORECAST PERIOD...MOST OF THE MODEL GUIDANCE
SUGGEST ONLY A GRADUAL BEND TO A WEST-NORTHWEST TRACK WITH AN
INCREASE IN FORWARD SPEED DUE TO A HIGH BUILDING OVER THE WESTERN
ATLANTIC.  THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY SOUTHWARD IN
THE FIRST FEW DAYS...BUT ENDS UP VERY CLOSE TO THE PREVIOUS
FORECAST BY THE END OF THE PERIOD.  
 
LIGHT TO MODERATE SOUTHEASTERLY SHEAR IS EXPECTED FOR THE NEXT
SEVERAL DAYS WHILE THE SYSTEM TRAVERSES MARGINALLY WARM WATERS.  IN
GENERAL...THIS ENVIRONMENT WOULD SUPPORT SOME STRENGTHENING...
THOUGH THE PRESENCE OF SOME DRIER/STABLE AIR JUST TO THE NORTH OF
THE DEPRESSION MAY PLAY AN INHIBITING ROLE.  THE STATISTICAL MODELS
SUGGEST THAT THE DEPRESSION COULD BE CLOSE TO HURRICANE STRENGTH IN
A FEW DAYS...WHILE THE DYNAMICAL GUIDANCE SHOWS ONLY A LOW-END
TROPICAL STORM.  THE NHC INTENSITY FORECAST WILL BASICALLY SPLIT
THE DIFFERENCE BETWEEN THOSE OUTCOMES AND REMAINS CLOSE TO THE
PREVIOUS ONE.  IN THE LONGER-TERM...MOST OF THE GLOBAL MODELS
INCREASE THE VERTICAL SHEAR...WHICH SHOULD CAUSE A WEAKENING TREND
WHILE THE SYSTEM IS OVER THE CENTRAL ATLANTIC.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      12/0900Z 14.6N  32.4W    30 KT
 12HR VT     12/1800Z 14.6N  34.0W    35 KT
 24HR VT     13/0600Z 14.6N  36.4W    35 KT
 36HR VT     13/1800Z 14.6N  38.9W    40 KT
 48HR VT     14/0600Z 15.0N  41.4W    45 KT
 72HR VT     15/0600Z 16.5N  46.5W    50 KT
 96HR VT     16/0600Z 19.0N  52.5W    45 KT
120HR VT     17/0600Z 22.5N  58.5W    40 KT
 
$$
FORECASTER BLAKE
 

WTNT42 KNHC 121442
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 AM AST WED AUG 12 2009
 
TROPICAL DEPRESSION TWO SHOWS A CLASSICAL SHEAR PATTERN IN SATELLITE
IMAGERY THIS MORNING...WITH UPPER-LEVEL EASTERLY WINDS DISPLACING
THE CONVECTION TO THE WEST OF THE EXPOSED LOW-LEVEL CENTER.
SATELLITE INTENSITY ESTIMATES HAVE INCREASED TO 35 KT FROM TAFB AND
SAB. HOWEVER...A QUIKSCAT OVERPASS AT 0812Z DID NOT SHOW
TROPICAL-STORM-FORCE WIND VECTORS THAT LOOKED RELIABLE. THUS...THE
INITIAL INTENSITY REMAINS 30 KT FOR THIS ADVISORY. AT THIS TIME...
MOST OF THE LOW-LEVEL INFLOW INTO THE DEPRESSION SEEMS TO BE COMING
FROM THE NORTH...REPRESENTING POSSIBLY MORE STABLE AIR PASSING OVER
COOLER WATERS. THE FLOW ON THE SOUTH SIDE OF THE DEPRESSION IS
FEEDING INTO A LARGE DISTURBANCE BETWEEN THE CAPE VERDE ISLANDS AND
AFRICA.

THE INITIAL MOTION IS NOW 265/11.  THE DEPRESSION IS ON THE SOUTH
SIDE OF A LARGE LOW/MID-LEVEL RIDGE...AND THE LARGE-SCALE MODELS
FORECAST THIS TO CONTINUE FOR THE NEXT TWO DAYS OR SO.  AFTER THAT
TIME...THE MODELS FORECAST A SERIES OF MID/UPPER-LEVEL WEAKNESSES IN
THE RIDGE THAT WOULD STEER THE CYCLONE WEST-NORTHWESTWARD.  THE
TRACK MODEL GUIDANCE MOSTLY AGREES WITH THIS SCENARIO...ALTHOUGH
THERE ARE TWO CLUSTERS IN THE GUIDANCE.  THE HWRF...BAMD...LBAR...
AND CLIPER CALL FOR AN EARLIER WEST-NORTHWESTWARD MOTION...AND AS A
RESULT THEY WIND UP NORTH OF THE OTHER GUIDANCE BY DAY 5.  THE NEW
FORECAST TRACK...WHICH IS ADJUSTED TO THE SOUTH OF THE PREVIOUS
FORECAST...IS DOWN THE MIDDLE OF THE SOUTHERN GUIDANCE CLUSTER IN
BEST OVERALL AGREEMENT WITH THE CONSENSUS MODELS TVCN AND TVCC. 
ALTHOUGH IT APPEARS UNLIKELY...THE UKMET SUGGESTS AN ALTERNATIVE
SCENARIO...WITH THE DEPRESSION WEAKENING AND THE REMNANTS MOVING
WEST INTO THE CARIBBEAN.

THE DEPRESSION IS CURRENTLY OVER SEA SURFACE TEMPERATURES NEAR
27C...AND THE SSTS ALONG THE FORECAST TRACK INCREASE TO 28C AFTER
72 HR.  THE LARGE-SCALE MODELS FORECAST THE DEPRESSION TO ENCOUNTER
MODERATE VERTICAL WIND SHEAR DURING THE FORECAST PERIOD...FIRST
FROM THE EAST AND LATER FROM THE SOUTH AND WEST.  ALSO...WATER
VAPOR IMAGERY SHOWS VERY DRY AIR AT THE MID/UPPER-LEVELS TO THE
NORTHWEST OF THE DEPRESSION.  THE LATTER TWO FACTORS SUGGEST THE
SYSTEM MAY BE SLOW TO STRENGTHEN...AND AT THIS TIME NONE OF THE
INTENSITY GUIDANCE FORECASTS AN INTENSITY OF HIGHER THAN 55 KT
DURING THE FORECAST PERIOD.  THE NEW INTENSITY FORECAST IS SIMILAR
TO THE PREVIOUS FORECAST IN CALLING FOR A 50 KT INTENSITY IN 72
HR...AND IT IS IN BEST AGREEMENT WITH THE SHIPS MODEL.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      12/1500Z 14.3N  33.8W    30 KT
 12HR VT     13/0000Z 14.2N  35.4W    35 KT
 24HR VT     13/1200Z 14.2N  37.6W    35 KT
 36HR VT     14/0000Z 14.2N  40.1W    40 KT
 48HR VT     14/1200Z 14.5N  42.8W    45 KT
 72HR VT     15/1200Z 16.0N  48.5W    50 KT
 96HR VT     16/1200Z 19.0N  54.5W    50 KT
120HR VT     17/1200Z 23.0N  60.5W    45 KT
 
$$
FORECASTER BEVEN
 

WTNT42 KNHC 122034
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 PM AST WED AUG 12 2009

THE DEPRESSION APPEARED TO BE ON THE VERGE OF BECOMING A TROPICAL
STORM A FEW HOURS AGO...WITH SATELLITE INTENSITY ESTIMATES OF 35 KT
FROM TAFB AND SAB.  HOWEVER...SINCE ABOUT 18Z THE CONVECTION HAS
DECREASED SIGNIFICANTLY AND HAS MOVED FARTHER AWAY FROM THE EXPOSED
LOW-LEVEL CENTER.  BASED ON THIS...THE CYCLONE WILL REMAIN A 30 KT
DEPRESSION FOR THIS ADVISORY.  THE CURRENT DOWNWARD TREND IN THE
CONVECTION MAY BE DUE TO AN INCREASE IN EASTERLY VERTICAL WIND
SHEAR...AND TO A DRY SLOT WRAPPING AROUND THE CIRCULATION NOTED IN
AMSR-E VAPOR IMAGERY NEAR 1534Z.  ALSO...AS SEEN EARLIER...MOST OF
THE LOW-LEVEL INFLOW INTO THE DEPRESSION SEEMS TO BE COMING FROM
THE NORTH...REPRESENTING POSSIBLY MORE STABLE AIR PASSING OVER
COOLER WATERS.  THE FLOW ON THE SOUTH SIDE OF THE DEPRESSION IS
FEEDING INTO A LARGE DISTURBANCE BETWEEN THE CAPE VERDE ISLANDS AND
AFRICA.
 
THE INITIAL MOTION IS 265/12.  THE DEPRESSION IS ON THE SOUTH
SIDE OF A LARGE LOW/MID-LEVEL RIDGE...AND THE LARGE-SCALE MODELS
FORECAST THIS TO CONTINUE FOR THE NEXT TWO DAYS OR SO.  AFTER THAT
TIME...THE MODELS FORECAST A WEAKNESS IN THE RIDGE THAT WOULD STEER
THE CYCLONE WEST-NORTHWESTWARD.  THE TRACK MODEL GUIDANCE GENERALLY
AGREES WITH THIS SCENARIO...AND WHILE THE MODEL CLUSTERS SEEN
EARLIER HAVE MERGED THERE IS STILL A SIGNIFICANT SPREAD BY 120 HR.
THE GFS AND UKMET ARE ON THE SOUTH SIDE OF THE GUIDANCE ENVELOPE
SHOWING A MORE WESTERLY MOTION...WHILE THE HWRF AND BAMD ARE ON THE
NORTH SIDE SHOWING A NORTHWESTWARD MOTION BY 120 HR.  OVERALL...THE
GUIDANCE ENVELOPE HAS AGAIN SHIFTED A LITTLE SOUTHWARD...AND SO HAS
THE NEW OFFICIAL FORECAST.  THE NEW TRACK IS IN THE CENTER OF THE
GUIDANCE ENVELOPE IN BEST AGREEMENT WITH THE TVCN AND TVCC
CONSENSUS MODELS.
 
THE DEPRESSION REMAINS OVER SEA SURFACE TEMPERATURES NEAR 27C...WITH
SSTS ALONG THE FORECAST TRACK INCREASING TO 28C AFTER 72 HR.  THE
LARGE-SCALE MODELS FORECAST THE DEPRESSION TO ENCOUNTER MODERATE
VERTICAL WIND SHEAR DURING THE FORECAST PERIOD...FIRST FROM THE
EAST AND LATER FROM THE SOUTHWEST.  ALSO...WATER VAPOR IMAGERY
SHOWS VERY DRY AIR AT THE MID/UPPER-LEVELS TO THE NORTHWEST OF THE
DEPRESSION.  THE LATTER TWO FACTORS SUGGEST THE SYSTEM MAY BE SLOW
TO STRENGTHEN...AND NONE OF THE INTENSITY GUIDANCE CURRENTLY
FORECASTS AN INTENSITY GREATER THAN 55 KT DURING THE FORECAST
PERIOD.  BASED ON THIS...THE NEW INTENSITY FORECAST IS AN UPDATE OF
THE PREVIOUS FORECAST IN BEST AGREEMENT WITH THE SHIPS MODEL.  IT
IS POSSIBLE THAT THE SYSTEM COULD WEAKEN TO A TROPICAL WAVE DURING
THE FORECAST PERIOD...AS FORECAST BY THE ECMWF...UKMET...AND GFS
MODELS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      12/2100Z 14.3N  35.0W    30 KT
 12HR VT     13/0600Z 14.1N  36.7W    35 KT
 24HR VT     13/1800Z 14.1N  38.9W    35 KT
 36HR VT     14/0600Z 14.2N  41.3W    40 KT
 48HR VT     14/1800Z 14.6N  43.7W    45 KT
 72HR VT     15/1800Z 16.0N  49.5W    50 KT
 96HR VT     16/1800Z 19.0N  56.0W    50 KT
120HR VT     17/1800Z 23.0N  62.0W    45 KT
 
$$
FORECASTER BEVEN
 

WTNT42 KNHC 130245
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 PM AST WED AUG 12 2009
 
AFTER BEING ON THE VERGE OF TROPICAL STORM STATUS EARLIER THIS
AFTERNOON...THE DEPRESSION HAS MADE A COMPLETE TURNAROUND AND IS
NOW VIRTUALLY DEVOID OF DEEP CONVECTION.  THE LOW-LEVEL CENTER IS
EXPOSED TO THE EAST OF WHAT CONVECTION IS LEFT...AND A 2042 UTC
QUIKSCAT PASS BARELY SHOWED 30 KT.  THE INITIAL INTENSITY IS HELD
AT 30 KT...BUT THIS COULD BE GENEROUS.  SHIPS GUIDANCE IS CURRENTLY
DIAGNOSING 15-20 KT OF EASTERLY SHEAR OVER THE DEPRESSION AND KEEPS
IT FOR ANOTHER 2-3 DAYS.  IN ADDITION...DRY AIR AND MARGINALLY WARM
SEA SURFACE TEMPERATURES WILL LIKELY INHIBIT MUCH STRENGTHENING
OVER THE NEXT FEW DAYS.  THE OFFICIAL FORECAST NOW ONLY SHOWS THE
SYSTEM REACHING 45 KT...AND THIS IS STILL HIGHER THAN ICON...THE
CONSENSUS OF THE INTENSITY MODELS.  VERTICAL SHEAR IS EXPECTED TO
INCREASE AGAIN BY DAY 5...THIS TIME STRONGER AND FROM THE WEST...
AND THE FORECAST CONTINUES TO SHOW WEAKENING AT THAT POINT.  ALL OF
THIS IS MOOT IF DEEP CONVECTION DOES NOT RE-DEVELOP SOON...IN WHICH
CASE WE WOULD LIKELY TERMINATE ADVISORIES.
 
THE DEPRESSION HAS BEEN MOVING JUST SOUTH OF DUE WEST AT 260/12.
THE GUIDANCE ENVELOPE CONTINUES TO INDICATE A WEST-NORTHWESTWARD
TURN IN ABOUT 2-3 DAYS AS A WEAKNESS DEVELOPS IN THE SUBTROPICAL
RIDGE...BUT THIS TURN COULD BE DELAYED IF THE DEPRESSION DOES NOT
STRENGTHEN AND BECOMES STEERED BY THE LOW-LEVEL FLOW.  THE NEW
FORECAST IS SHIFTED A LITTLE MORE TO THE SOUTH TOWARDS THE MODEL
CONSENSUS.  THE HWRF WAS NOT INCLUDED IN THIS CONSENSUS SINCE IT
HAS BEEN A CONSISTENT NORTHERN OUTLIER FOR A COUPLE OF DAYS.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/0300Z 14.0N  36.3W    30 KT
 12HR VT     13/1200Z 14.0N  37.9W    30 KT
 24HR VT     14/0000Z 14.1N  40.1W    35 KT
 36HR VT     14/1200Z 14.3N  42.4W    40 KT
 48HR VT     15/0000Z 14.7N  44.8W    45 KT
 72HR VT     16/0000Z 16.5N  51.0W    45 KT
 96HR VT     17/0000Z 19.0N  57.5W    45 KT
120HR VT     18/0000Z 23.0N  64.0W    40 KT
 
$$
FORECASTER BERG
 

WTNT42 KNHC 130840
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 AM AST THU AUG 13 2009
 
THE DEPRESSION HAS A RATHER MEAGER AMOUNT OF CONVECTION THIS MORNING
WITH JUST A FEW CELLS AROUND THE EXPOSED CENTER.   SATELLITE
INTENSITY ESTIMATES ARE DROPPING...SO THE INITIAL INTENSITY IS
LOWERED TO 25 KT.  IF SIGNIFICANT DEEP CONVECTION DOES NOT DEVELOP
SOON... THE SYSTEM COULD BE DECLARED A REMNANT LOW LATER TODAY. 
ASSUMING THE DEPRESSION SURVIVES...THE ENVIRONMENT OVER THE NEXT
FEW DAYS IS MARGINALLY CONDUCIVE FOR SOME STRENGTHENING WITH
GRADUALLY INCREASING WATER TEMPERATURES WEST OF 40W AND PERHAPS A
DECREASE IN MODERATE SOUTHEASTERLY SHEAR.  THE INTENSITY FORECAST
IS LOWERED FROM THE PREVIOUS ONE BUT STILL SHOWS THE DEPRESSION
EVENTUALLY BECOMING A TROPICAL STORM.  THIS IS A PRETTY LOW
CONFIDENCE INTENSITY FORECAST AS THE DEPRESSION MAY NOT EVEN
SURVIVE THE DAY.
 
THE SYSTEM HAS BEEN MOVING SLOWER DURING THE PAST FEW HOURS...AND A
TWELVE-HOUR MOTION IS ESTIMATED AT 270/10.  MOST OF THE GUIDANCE
SUGGEST THAT THIS WESTWARD MOTION SHOULD CONTINUE FOR A DAY OR SO
WITH A GRADUAL TURN TO THE WEST-NORTHWEST THEREAFTER AS A WEAKNESS
DEVELOPS IN THE SUBTROPICAL RIDGE.  THE GLOBAL MODELS NOW INDICATE
THAT THE DEPRESSION COULD BE TOO FAR SOUTH TO BE AFFECTED
SIGNIFICANTLY BY THE WEAKNESS IN THE RIDGE AND HAVE SHIFTED THE
TRACK EQUATORWARD AS A RESULT.  THE HWRF CONTINUES ON ITS OWN BY
MOVING THE SYSTEM MORE TO THE NORTH...WHILE THE REST OF THE
GUIDANCE IS PRETTY WELL-CLUSTERED ON A MORE SOUTHERN PATH.  THE
OFFICIAL FORECAST IS ADJUSTED SOUTHWARD AND WITH MANY RELIABLE
MODELS STILL SOUTH OF THE NHC TRACK...IT WOULD NOT BE SURPRISING TO
SEE THE FORECAST MOVE FARTHER SOUTH LATER ON.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/0900Z 14.0N  36.9W    25 KT
 12HR VT     13/1800Z 14.0N  38.5W    25 KT
 24HR VT     14/0600Z 14.2N  40.7W    30 KT
 36HR VT     14/1800Z 14.4N  43.0W    35 KT
 48HR VT     15/0600Z 14.9N  45.9W    40 KT
 72HR VT     16/0600Z 16.5N  52.0W    40 KT
 96HR VT     17/0600Z 19.0N  59.0W    40 KT
120HR VT     18/0600Z 22.5N  65.0W    35 KT
 
$$
FORECASTER BLAKE
 

WTNT42 KNHC 131433
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 AM AST THU AUG 13 2009

TROPICAL DEPRESSION TWO CURRENTLY CONSISTS OF A SWIRL OF LOW CLOUDS
WITH ISOLATED SHOWERS AND THUNDERSTORMS...TOO FEW TO GET A DATA-T
NUMBER USING THE DVORAK TECHNIQUE.  SSMI/DATA AT ABOUT 09Z
SUGGESTED 25 KT WINDS IN THE NORTHERN SEMICIRCLE...AND THAT IS USED
AS THE INITIAL INTENSITY.  SSM/I AND AMSR-E PRECIPITABLE WATER
IMAGERY SUGGESTS THAT A TONGUE OF DRIER AIR HAS WRAPPED ALMOST ALL
THE WAY AROUND THE CIRCULATION...AND WATER VAPOR IMAGERY SHOWS
MID/UPPER-LEVEL DRY AIR IN THE VICINITY OF THE DEPRESSION.  THESE
FACTORS...COMBINED WITH ABOUT 15 KT OF EASTERLY VERTICAL WIND
SHEAR...MAY BE PREVENTING THE SYSTEM FROM MAINTAINING ORGANIZED
CONVECTION.
 
THE INITIAL MOTION IS NOW 270/8.  THERE IS LITTLE CHANGE TO THE
FORECAST PHILOSOPHY FROM THE PREVIOUS FORECAST.  THE DEPRESSION IS
ON THE SOUTH SIDE OF A LOW/MID-LEVEL RIDGE...WHICH SHOULD RESULT IN
A WESTWARD MOTION FOR THE NEXT COUPLE OF DAYS.  AFTER THAT...THE
SYSTEM SHOULD GRADUALLY TURN WEST-NORTHWESTWARD TOWARD A WEAKNESS
IN THE RIDGE OVER THE WESTERN ATLANTIC.  THE OVERALL GUIDANCE
ENVELOPE HAS SHIFTED SOUTHWARD SINCE THE LAST ADVISORY...SO THE NEW
FORECAST TRACK IS ALSO SHIFTED SOUTHWARD.  IT SHOULD BE NOTED THAT
IF THE CYCLONE WEAKENS TO A TROPICAL WAVE...THE REMNANTS WOULD
LIKELY MOVE FARTHER SOUTH THAN CURRENTLY FORECAST...AS SHOWN BY THE
BAMM AND BAMS MODELS.
 
THE SHIPS MODEL CONTINUES TO FORECAST MODERATE TO OCCASIONALLY
STRONG SHEAR OVER THE SYSTEM DURING THE FORECAST PERIOD...AND THUS
THE SHIPS AND LGEM MODELS SHOW LITTLE OR NO STRENGTHENING.  ON THE
OTHER HAND...THE HWRF AND GFDN SHOW SIGNIFICANT STRENGTHENING...
WITH THE HWRF MAKING THE SYSTEM A HURRICANE BY 120 HR.  BASED ON
THE FORECAST SHEAR AND CURRENT TRENDS...THE INTENSITY FORECAST NOW
CALLS FOR LITTLE CHANGE IN STRENGTH DURING THE FORECAST PERIOD IN
BEST AGREEMENT WITH THE LGEM MODEL.  THERE IS A DISTINCT
POSSIBILITY THE CYCLONE COULD WEAKEN TO A REMNANT LOW OR TROPICAL
WAVE DURING THE FORECAST PERIOD...AS FORECAST BY ALL THE GLOBAL
MODELS EXCEPT THE NOGAPS.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/1500Z 14.0N  37.6W    25 KT
 12HR VT     14/0000Z 14.0N  39.1W    25 KT
 24HR VT     14/1200Z 14.2N  41.3W    25 KT
 36HR VT     15/0000Z 14.4N  43.9W    25 KT
 48HR VT     15/1200Z 14.8N  46.6W    25 KT
 72HR VT     16/1200Z 16.0N  52.5W    25 KT
 96HR VT     17/1200Z 18.5N  59.5W    25 KT
120HR VT     18/1200Z 22.0N  66.0W    25 KT
 
$$
FORECASTER BEVEN
 

WTNT42 KNHC 132041
TCDAT2
TROPICAL DEPRESSION TWO DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 PM AST THU AUG 13 2009

WHILE PERSISTING OVER THE PAST SEVERAL HOURS...THE AREA OF
CONVECTION JUST WEST OF THE CENTER OF TROPICAL DEPRESSION TWO IS
TOO SMALL TO BE CLASSIFIED USING THE DVORAK TECHNIQUE.  INDEED...IT
HAS BEEN ALMOST 24 HR SINCE ENOUGH ORGANIZED CONVECTION EXISTED TO
GET A DATA-T NUMBER.  BASED ON THIS...THE DEPRESSION HAS DECAYED
INTO A REMNANT LOW PRESSURE AREA.  IT IS LIKELY THAT THE SYSTEM
WILL CONTINUE TO PRODUCE BURSTS OF CONVECTION FOR THE NEXT SEVERAL
DAYS...AND A FASTER FORWARD MOTION IS EXPECTED BY THE END OF THE
FORECAST PERIOD.  THIS IS THE BASIS FOR KEEPING A 25 KT INTENSITY
FOR THE REMNANTS THROUGH 120 HR.  SEVERAL OF THE INTENSITY FORECAST
MODELS CONTINUE TO FORECAST STRENGTHENING...SO IF THE SYSTEM FINDS
A MORE FAVORABLE ENVIRONMENT IT COULD REGENERATE.

THE INITIAL MOTION IS 275/8.  THERE IS LITTLE CHANGE TO THE
FORECAST PHILOSOPHY FROM THE PREVIOUS FORECAST.  THE SYSTEM IS
ON THE SOUTH SIDE OF A LOW/MID-LEVEL RIDGE...WHICH SHOULD RESULT IN
A WESTWARD MOTION FOR THE NEXT COUPLE OF DAYS.  AFTER THAT...IT
SHOULD GRADUALLY TURN WEST-NORTHWESTWARD TOWARD A WEAKNESS IN THE
RIDGE OVER THE WESTERN ATLANTIC.  THE NEW FORECAST TRACK IS
BASICALLY AN UPDATE OF THE PREVIOUS ADVISORY.  IT SHOULD BE NOTED
THAT SEVERAL GLOBAL MODELS SHOW THE REMNANT LOW WEAKENING TO A
TROPICAL WAVE...AND IF THIS OCCURS THE SYSTEM COULD MOVE FARTHER
SOUTH THAN CURRENTLY FORECAST.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/2100Z 14.2N  38.3W    25 KT...REMNANT LOW
 12HR VT     14/0600Z 14.3N  39.7W    25 KT...REMNANT LOW
 24HR VT     14/1800Z 14.5N  42.2W    25 KT...REMNANT LOW
 36HR VT     15/0600Z 14.8N  44.8W    25 KT...REMNANT LOW
 48HR VT     15/1800Z 15.1N  47.7W    25 KT...REMNANT LOW
 72HR VT     16/1800Z 16.5N  54.0W    25 KT...REMNANT LOW
 96HR VT     17/1800Z 19.0N  61.0W    25 KT...REMNANT LOW
120HR VT     18/1800Z 23.0N  67.5W    25 KT...REMNANT LOW
 
$$
FORECASTER BEVEN
 

WTNT42 KNHC 150426
TCDAT2
TROPICAL DEPRESSION TWO SPECIAL DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1230 AM AST SAT AUG 15 2009
 
SATELLITE IMAGERY INDICATES THAT THE REMNANT CIRCULATION OF TROPICAL
DEPRESSION TWO HAS REGENERATED INTO A TROPICAL CYCLONE. DATA FROM
A NOAA G-IV MISSION...NOAA BUOY 41041...AND A RECENTLY-RECEIVED
ASCAT PASS INDICATES THAT THE CIRCULATION IS WELL-DEFINED. THE BUOY
ALSO REPORTED 1006.4 MB AND NORTH-NORTHWEST WINDS OF 19 KT. 
ORGANIZED CONVECTION HAS NOW PERSISTED NEAR THE CENTER LONG
ENOUGH TO CONSIDER THIS SYSTEM A TROPICAL DEPRESSION. THE INITIAL
INTENSITY IS SET TO 30 KT...IN AGREEMENT WITH A SPECIAL DVORAK
CLASSIFICATION FROM TAFB AND WINDS FROM ASCAT.
 
THE INITIAL MOTION ESTIMATE IS 270/13. THE GLOBAL MODELS ARE IN
AGREEMENT THAT DEEP LAYER RIDGING WILL PERSIST NORTH OF THE
TROPICAL CYCLONE FOR THE NEXT SEVERAL DAYS...WHICH SHOULD STEER THE
SYSTEM IN A WEST OR WEST-NORTHWESTWARD DIRECTION.  IN A FEW
DAYS...THE CYCLONE WILL BE APPROACHING THE WESTERN PERIPHERY OF THE
SUBTROPICAL RIDGE TO NORTH...WHICH COULD ALLOW THE SYSTEM TO MOVE
MORE TOWARD THE NORTHWEST. FOR SUCH A WEAK SYSTEM...THE TRACK
GUIDANCE IS IN GOOD AGREEMENT THROUGH THE PERIOD...AND THE OFFICIAL
FORECAST IS CLOSE TO THE MULTI-MODEL CONSENSUS. HOWEVER...NOW THAT
THE SYSTEM IS BEING INITIALIZED AS A TROPICAL CYCLONE IN MOST OF
THE GLOBAL MODEL FIELDS...IT WOULD NOT BE SURPRISING TO SEE CHANGES
IN THE GUIDANCE DURING THE NEXT COUPLE OF GUIDANCE CYCLES.
 
RELATIVELY LOW SHEAR IS FORECAST BY THE SHIPS MODEL FOR THE NEXT DAY
OR SO WHILE THE SYSTEM REMAINS UNDER THE SOUTHWEST PORTION OF AN
UPPER HIGH OVER THE CENTRAL ATLANTIC.  THEREAFTER...AN UPPER TROUGH
TO THE NORTHWEST OF THE TROPICAL CYCLONE COULD INDUCE SOME WESTERLY
SHEAR.  GIVEN THIS...THE INTENSITY FORECAST ONLY SHOWS SLOW
INTENSIFICATION THOUGH 48 HOURS AND LITTLE CHANGE AFTER THAT.  THE
OFFICIAL FORECAST IS CLOSE TO A BLEND OF THE SHIPS/LGEM/HWRF
MODELS. HOWEVER...IT IS WORTH NOTING THAT THE INTENSITY PROBABILITY
TABLE SHOWS ABOUT A 25 PERCENT CHANCE THAT THIS SYSTEM COULD BE A
HURRICANE AFTER 48 HOURS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/0430Z 14.6N  45.8W    30 KT
 12HR VT     15/1200Z 14.7N  47.6W    30 KT
 24HR VT     16/0000Z 15.0N  51.0W    40 KT
 36HR VT     16/1200Z 16.0N  54.5W    45 KT
 48HR VT     17/0000Z 17.0N  58.0W    50 KT
 72HR VT     18/0000Z 19.5N  65.0W    50 KT
 96HR VT     19/0000Z 22.0N  71.0W    50 KT
120HR VT     20/0000Z 25.5N  76.5W    50 KT
 
$$
FORECASTER BLAKE/BRENNAN
 

