WTNT42 KNHC 150840
TCDAT2
TROPICAL STORM ANA DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 AM AST SAT AUG 15 2009
 
SATELLITE IMAGES INDICATE THAT THE TROPICAL DEPRESSION HAS CONTINUED
TO BECOME BETTER ORGANIZED AND IS NOW UPGRADED TO TROPICAL STORM
ANA. THE STORM IS DISPLAYING IMPROVED BANDING IN THE WESTERN
SEMICIRCLE ALONG WITH A BALL OF CONVECTION NEAR THE CENTER. NOAA
BUOY 41041 REPORTED A MINIMUM PRESSURE OF ABOUT 1005 MB AS THE
DEPRESSION PASSED VERY NEAR THE BUOY. THE INITIAL INTENSITY IS
RAISED TO 35 KT FOR THIS ADVISORY IN AGREEMENT WITH DVORAK
INTENSITY ESTIMATES FROM SAB AND TAFB.

THE INITIAL MOTION ESTIMATE IS 270/14. THE GLOBAL MODELS ARE IN
AGREEMENT THAT A DEEP-LAYER RIDGE WILL STRENGTHEN NORTH OF THE
TROPICAL CYCLONE OVER THE NEXT DAY OR SO. THIS PATTERN FAVORS THE
TRACK OF ANA GRADUALLY BENDING FROM A WEST TO A WEST-NORTHWEST
DIRECTION WITH AN INCREASE IN FORWARD SPEED. THE ONLY SIGNIFICANT
OUTLIERS TO THIS TRACK ARE THE GFDL AND GFS...WHICH BOTH WEAKEN THE
SYSTEM RATHER QUICKLY...LEADING TO A MORE WESTWARD TRACK OF THE
CYCLONE. IN A FEW DAYS...SOME OF THE MODELS...SUCH AS THE GFS...
SHOW A WEAKNESS IN THE RIDGE OVER THE WESTERN ATLANTIC THAT COULD
ALLOW THE CYCLONE TO GAIN A LITTLE MORE LATITUDE. THIS WEAKNESS
APPEARS TO BE CAUSED BY THE MID- TO UPPER-LEVEL LOW CURRENTLY NEAR
25N 65W. HOWEVER...THE MAJORITY OF THE GUIDANCE SHOWS THE MID- TO
UPPER-LEVEL LOW MOVING WEST-SOUTHWESTWARD WITH MINIMAL INFLUENCE ON
THE STRENGTH OF THE RIDGE. GENERALLY...THE MODELS THAT HOLD ONTO
ANA ARE IN GOOD AGREEMENT THROUGHOUT THE FORECAST PERIOD. THE NHC
TRACK FORECAST IS SHIFTED TOWARD THE SOUTHWEST FOR THIS ADVISORY...
BUT NOT AS FAR AS THE MODEL CONSENSUS.

THE 0000 UTC GLOBAL MODELS GENERALLY FORECAST A MORE CONDUCIVE
ENVIRONMENT FOR STRENGTHENING THAN PREVIOUS CYCLES...SHOWING A
WEAKER MID-OCEANIC TROUGH AFFECTING THE SYSTEM. IN PARTICULAR...THE
UKMET AND NOGAPS BUILD UPPER-RIDGING NEAR THE CYCLONE WITH LIGHT
SHEAR THROUGH THE PERIOD. HOWEVER...THE ECMWF SHOWS SOME WESTERLY
SHEAR DEVELOPING IN ABOUT A DAY...BUT EVEN THAT MODEL HAS LIGHTER
SHEAR CONDITIONS IN A FEW DAYS. THE INTENSITY GUIDANCE RUNS THE
FULL SPECTRUM THIS MORNING...WITH THE GFDL DISSIPATING THE
SYSTEM...WHILE THE HWRF SHOWS A CATEGORY TWO HURRICANE BY THE END
OF THE FORECAST PERIOD. GIVEN THE UNCERTAINTY IN THE UPPER-LEVEL
ENVIRONMENT LATER IN THE FORECAST PERIOD...THE OFFICIAL INTENSITY
FORECAST IS INCREASED CONSERVATIVELY...IN BEST AGREEMENT WITH THE
SHIPS MODEL BUT BELOW THE INTENSITY CONSENSUS.

A TROPICAL STORM WATCH MAY BE REQUIRED FOR PORTIONS OF THE LEEWARD
ISLANDS LATER TODAY.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/0900Z 14.6N  46.8W    35 KT
 12HR VT     15/1800Z 14.7N  49.4W    40 KT
 24HR VT     16/0600Z 15.3N  52.7W    45 KT
 36HR VT     16/1800Z 16.1N  56.4W    45 KT
 48HR VT     17/0600Z 17.0N  60.0W    50 KT
 72HR VT     18/0600Z 19.5N  67.0W    55 KT
 96HR VT     19/0600Z 22.5N  73.0W    60 KT
120HR VT     20/0600Z 26.0N  78.5W    60 KT
 
$$
FORECASTER BLAKE
 

WTNT42 KNHC 151455
TCDAT2
TROPICAL STORM ANA DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 AM AST SAT AUG 15 2009

MORNING SATELLITE IMAGERY SHOWS THAT THE CENTER OF ANA HAS BECOME
EXPOSED TO THE WEST OF THE CENTRAL CONVECTIVE AREA...SUGGESTING
SOME WESTERLY VERTICAL WIND SHEAR HAS DEVELOPED.  SATELLITE
INTENSITY ESTIMATES FROM TAFB AND SAB REMAIN 35 KT...AND THAT
REMAINS THE INITIAL INTENSITY.

THE EXPOSED CENTER IS A LITTLE SOUTH OF THE PREVIOUS ADVISORY
POSITION...AND THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 270/14. 
OVERALL...A LOW/MID-LEVEL RIDGE SHOULD STEER ANA QUICKLY WEST-
NORTHWESTWARD...WITH ALL THE TRACK GUIDANCE AGREEING WITH THIS
SCENARIO.  HOWEVER...THERE IS A SIGNIFICANT SPREAD IN THE 120 HR
FORECAST POINTS.  THE ECMWF AND BAMS ARE AT THE NORTHERN EXTREME...
FORECASTING ANA TO BE OVER OR NEAR THE FLORIDA PENINSULA AT 120 HR. 
AT THE OTHER EXTREME ARE THE GFDL AND GFDN...WHICH FORECAST ANA TO
PASS SOUTH OF HISPANIOLA AND BE OVER THE NORTHWESTERN CARIBBEAN AT
120 HR.  THE NEW FORECAST TRACK IS SHIFTED A BIT TO THE SOUTH AND
WEST OF THE PREVIOUS TRACK IN BEST AGREEMENT WITH THE NOGAPS AND
THE HWRF.  HOWEVER...THE NEW TRACK IS STILL ON THE NORTHERN SIDE OF
THE GUIDANCE ENVELOPE AND NORTH OF THE CONSENSUS MODELS.

THE CURRENT SHEAR WAS NOT WELL FORECAST BY THE LARGE-SCALE
MODELS...AND IT IS UNCLEAR WHETHER THIS IS A TEMPORARY TREND OR A
SIGN OF LONG-TERM TROUBLE FOR ANA.  THE LARGE-SCALE MODELS SUGGEST
THAT LIGHT TO MODERATE SHEAR COULD AFFECT ANA EARLY AND LATE IN THE
FORECAST PERIOD...WITH THE LIGHTEST SHEAR NEAR THE 72 HR TIME. 
BASED ON THIS AND THE INCREASINGLY WARM WATER UNDER THE STORM...
MOST INTENSITY GUIDANCE FORECASTS ANA TO BECOME A HURRICANE.  ON
THE OTHER HAND...THE G-IV MISSION LAST NIGHT SUGGESTED THAT THE
CIRCULATION OF ANA LACKED VERTICAL DEPTH...ENDING AT ABOUT 500 MB. 
ADDITIONALLY...THE CYCLONE IS SURROUNDED BY DRY AIR IN WATER VAPOR
IMAGERY...AND MAY INTERACT WITH THE ISLAND OF HISPANIOLA IN 72 HR. 
BASED ON THIS...THE INTENSITY FORECAST CALLS FOR A PEAK INTENSITY
OF 60 KT...BELOW MOST OF THE GUIDANCE.  THIS INTENSITY FORECAST HAS
GREATER THAN NORMAL UNCERTAINTY.
 
A TROPICAL STORM WATCH MAY BE REQUIRED FOR PORTIONS OF THE LEEWARD
ISLANDS LATER TODAY.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/1500Z 14.3N  48.3W    35 KT
 12HR VT     16/0000Z 14.6N  50.9W    40 KT
 24HR VT     16/1200Z 15.2N  54.4W    45 KT
 36HR VT     17/0000Z 16.1N  58.2W    50 KT
 48HR VT     17/1200Z 17.3N  62.0W    55 KT
 72HR VT     18/1200Z 19.5N  69.0W    60 KT
 96HR VT     19/1200Z 22.0N  74.5W    60 KT
120HR VT     20/1200Z 25.0N  80.0W    60 KT
 
$$
FORECASTER BEVEN
 

WTNT42 KNHC 152048
TCDAT2
TROPICAL STORM ANA DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 PM AST SAT AUG 15 2009
 
THE CENTER OF ANA CONTINUES TO BE EXPOSED TO THE WEST OF THE
CONVECTION BY MODERATE VERTICAL WIND SHEAR.  THE UPPER-LEVEL WINDS
NEAR ANA ARE CURRENTLY LIGHT AND SOUTHERLY...MOST OF THE
CONTRIBUTION TO THE SHEAR SEEMS TO BE FROM THE FAST LOW-LEVEL FLOW
THE CENTER IS EMBEDDED IN.  SATELLITE INTENSITY ESTIMATES FROM TAFB
AND SAB REMAIN 35 KT...AND THAT REMAINS THE INITIAL INTENSITY.
 
THE INITIAL MOTION IS 270/15.  OVERALL...A LOW/MID-LEVEL RIDGE
SHOULD STEER ANA QUICKLY WESTWARD TO WEST-NORTHWESTWARD...WITH ALL
THE TRACK GUIDANCE AGREEING WITH THIS SCENARIO.  HOWEVER...THERE
REMAINS A SIGNIFICANT SPREAD IN THE 120 HR FORECAST POINTS.  THE
ECMWF AND BAMS ARE AT THE NORTHERN EXTREME...FORECASTING ANA TO
PASS OVER OR NEAR THE SOUTHERN FLORIDA PENINSULA BY 120 HR.
AT THE OTHER EXTREME ARE THE UKMET...GFDN...AND BAMM...WHICH
FORECAST ANA TO PASS SOUTH OF HISPANIOLA AND BE OVER THE
NORTHWESTERN CARIBBEAN AT 120 HR.  THE NEW FORECAST TRACK IS AGAIN
SHIFTED SOUTHWARD FROM THE PREVIOUS TRACK IN BEST AGREEMENT WITH
THE NOGAPS.  HOWEVER...THE NEW TRACK IS STILL ON THE NORTHERN SIDE
OF THE GUIDANCE ENVELOPE AND NOTABLY NORTH OF THE CONSENSUS MODELS.
 
IT IS UNCLEAR WHETHER THE CURRENT SHEAR IS A TEMPORARY TREND OR A
SIGN OF LONG-TERM TROUBLE FOR ANA.  THE LARGE-SCALE MODELS SUGGEST
THE FORMER IS THE CASE...AND SO THE INTENSITY FORECAST CONTINUES TO
CALL FOR STRENGTHENING.  HOWEVER...THE CYCLONE IS STILL SURROUNDED
BY DRY AIR IN WATER VAPOR IMAGERY...AND THE NEW FORECAST TRACK NOW
CALLS FOR THE SYSTEM TO MAKE LANDFALL ON HISPANIOLA...AN OCCURRENCE
THAT HAS DESTROYED STORMS MUCH STRONGER THAN ANA.  THE INTENSITY
FORECAST ASSUMES THAT THE CIRCULATION WILL SURVIVE THIS PASSAGE AND
INTENSIFY OVER THE WATERS NORTH OF CUBA.  AS BEFORE...THIS
INTENSITY FORECAST HAS GREATER THAN NORMAL UNCERTAINTY.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/2100Z 14.4N  50.0W    35 KT
 12HR VT     16/0600Z 14.7N  52.5W    35 KT
 24HR VT     16/1800Z 15.4N  56.0W    40 KT
 36HR VT     17/0600Z 16.1N  59.5W    45 KT
 48HR VT     17/1800Z 17.2N  63.2W    50 KT
 72HR VT     18/1800Z 19.0N  70.0W    50 KT...INLAND
 96HR VT     19/1800Z 21.5N  76.0W    55 KT...OVER WATER
120HR VT     20/1800Z 24.5N  82.0W    60 KT
 
$$
FORECASTER BEVEN
 

WTNT42 KNHC 160247
TCDAT2
TROPICAL STORM ANA DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 PM AST SAT AUG 15 2009
 
THE CONVECTION NEAR THE CENTER OF ANA HAS BEEN PULSATING AND AFTER
AN INCREASE FOR A FEW HOURS...THE LOW LEVEL CENTER HAS BECOME
EXPOSED AGAIN. THIS MEANS ANNA IS NOT STRENGTHENING AND THE INITIAL
INTENSITY IS KEPT AT 35 KNOTS. A NOAA JET FLEW AGAIN TONIGHT AND ONE
OF THE DROPS NEAR THE CENTER MEASURED A SURFACE PRESSURE OF 1004 MB
WHICH WAS USED FOR THIS ADVISORY. THE SHEAR IS NOT VERY STRONG AS
DIAGNOSED BY THE SHIPS MODELS BUT THE LOW-LEVEL CENTER OF ANA IS
SIMPLY MOVING TOO FAST. THIS RAPID MOTION IS PROBABLY NOT TOO
CONDUCIVE FOR INTENSIFICATION.  IN FACT...THE ONLY DYNAMICAL MODELS
THAT KEEP ANA ARE THE UK AND THE NOGAPS.  THE REST OF THEM WEAKEN
ANA TO A TROPICAL WAVE. I AM TEMPTED TO SHOW WEAKENING BUT FOR
NOW...I AM GOING TO FOLLOW THE PREVIOUS FORECAST AND SHIPS MODEL
GUIDANCE. THE OFFICIAL FORECAST SHOWS SLOW STRENGTHENING THROUGH 48
HOURS FOLLOWED BY WEAKENING AS THE CYCLONE INTERACTS WITH
HISPANIOLA AND CUBA.

THE INITIAL MOTION IS 270/15. ANA IS EMBEDDED WITHIN STRONG AND
PERSISTENT TRADE WINDS AND ONLY A SMALL TURN TO THE WEST-NORTHWEST
WITH AN INCREASE IN FORWARD SPEED IS ANTICIPATED. THE OFFICIAL
FORECAST IS A LITTLE BIT SLOWER THAN MOST OF THE GUIDANCE BUT IS
WELL INSIDE THE ENVELOPE THROUGH 48 HOURS. THEREAFTER...SOME MODELS
KEEP A WEAKER ANA SOUTH OF CUBA AND OTHERS BRING THE CYCLONE OVER
CUBA AND INTO THE GULF OF MEXICO.  THE OFFICIAL TRACK FORECAST IS
VERY SIMILAR TO THE PREVIOUS ONE AND FOLLOWS THE NORTHERNMOST GROUP
OF MODELS. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0300Z 14.4N  51.5W    35 KT
 12HR VT     16/1200Z 14.7N  54.1W    35 KT
 24HR VT     17/0000Z 15.5N  57.5W    40 KT
 36HR VT     17/1200Z 16.5N  61.2W    45 KT
 48HR VT     18/0000Z 17.5N  65.0W    50 KT
 72HR VT     19/0000Z 19.5N  73.0W    30 KT...INLAND
 96HR VT     20/0000Z 22.5N  78.9W    35 KT...OVER WATER
120HR VT     21/0000Z 25.0N  83.6W    40 KT
 
$$
FORECASTER AVILA
 

WTNT42 KNHC 160904
TCDAT2
TROPICAL STORM ANA DISCUSSION NUMBER  17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 AM AST SUN AUG 16 2009
 
AN ASCAT PASS AT 00Z SUGGESTED THAT ANA WAS STILL A TROPICAL STORM
AT THAT TIME...BUT IT CONTINUES MOVING RAPIDLY WESTWARD WITH VERY
LITTLE ASSOCIATED CONVECTION...AND MAY HAVE WEAKENED.  FOR NOW
HOWEVER...THE ADVISORY INTENSITY IS UNCHANGED.  THE ENVIRONMENT
THROUGH WHICH ANA IS MOVING IS VERY DRY...AND THE SYSTEM HAS HAD
DIFFICULTY MAINTAINING CONVECTION.  THERE IS STILL INTENSITY
GUIDANCE SHOWING AT LEAST SOME SHORT TERM INTENSIFICATION...AND SO
THE OFFICIAL FORECAST WILL REFLECT THAT.  LATER ON...THE INTENSITY
FORECAST HAS BEEN LOWERED DUE TO ANTICIPATED INTERACTION WITH LAND.

THERE HAS BEEN LITTLE CHANGE TO THE TRACK FORECAST PHILOSOPHY.  ANA
REMAINS EMBEDDED WITHIN A STRONG TRADE WIND FLOW AND THE MODEL
GUIDANCE IS WELL CLUSTERED.  THE NEW OFFICIAL FORECAST IS A LITTLE
FASTER THAN THE PREVIOUS ONE BUT IS STILL SLOWER THAN MOST OF THE
GUIDANCE.   
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0900Z 14.6N  53.8W    35 KT
 12HR VT     16/1800Z 15.0N  56.6W    35 KT
 24HR VT     17/0600Z 15.9N  60.4W    40 KT
 36HR VT     17/1800Z 16.8N  64.6W    40 KT
 48HR VT     18/0600Z 17.6N  68.2W    45 KT
 72HR VT     19/0600Z 20.0N  76.0W    30 KT...INLAND
 96HR VT     20/0600Z 23.0N  82.0W    30 KT...INLAND
120HR VT     21/0600Z 25.0N  85.0W    30 KT
 
$$
FORECASTER FRANKLIN
 

WTNT42 KNHC 161443
TCDAT2
TROPICAL STORM ANA DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 AM AST SUN AUG 16 2009
 
ANA CONTINUES TO RACE WESTWARD...WITH LIMITED DEEP CONVECTION OVER
THE LOW-LEVEL CENTER. A 0950 UTC QUIKSCAT PASS SHOWED SOME
BELIEVABLE 30 KT WINDS...AND ASSUMING WINDS ARE HIGHER IN THE
CONVECTION NEAR THE CENTER THE INTENSITY IS HELD GENEROUSLY AT 
35 KT FOR THIS PACKAGE. AIRCRAFT RECONNAISSANCE WILL BE
INVESTIGATING THE CYCLONE EARLY THIS AFTERNOON AND SHOULD HELP
DETERMINE IF ANA IS STILL A TROPICAL STORM.

THE ENVIRONMENT NEAR AND AHEAD OF ANA IS RATHER DRY AND DOMINATED BY
SUBSIDENCE...AS INDICATED BY WATER VAPOR IMAGERY AND RADIOSONDE
DATA FROM THE LESSER ANTILLES. THE GFDL...SHIPS...AND LGEM CONTINUE
TO SUGGEST THAT ANA WILL INTENSIFY SOMEWHAT OVER THE NEXT COUPLE OF
DAYS. HOWEVER...GIVEN THE NEGATIVE FACTORS DISCUSSED ABOVE...ONLY
SLIGHT INTENSIFICATION IS SHOWN THROUGH 48 HOURS. BEYOND THAT
TIME...THE INTENSITY OF ANA WILL BE DICTATED PRIMARILY BY ITS
INTERACTION WITH HISPANIOLA AND CUBA...AND THE INTENSITY FORECAST
ACCOUNTS FOR THIS WITH WEAKENING. 

THE TRACK FORECAST IS QUITE SIMILAR TO THE PREVIOUS PACKAGE...
SHOWING A QUICK WESTWARD TO WEST-NORTHWESTWARD MOTION THROUGH THE
FIRST 3 OR 4 DAYS OF THE FORECAST PERIOD. BEYOND THAT TIME THERE
IS A SPLIT IN THE TRACK GUIDANCE...WITH THE ECMWF AND HWRF SHOWING
A TURN TOWARD THE NORTHWEST...WHILE THE UKMET AND NOGAPS SHOW A
CONTINUED WEST-NORTHWEST HEADING. THE OFFICIAL FORECAST IS NUDGED
TOWARD THE MULTI-MODEL CONSENSUS AT DAY 5 AND SHOWS A DECREASE IN
FORWARD SPEED. 

GIVEN THE UNCERTAINTY IN THE INITIAL INTENSITY OF ANA...TROPICAL
STORM WATCHES CONTINUE FOR MOST OF THE NORTHERN LEEWARD ISLANDS...
THE VIRGIN ISLANDS...AND PUERTO RICO. IF AIRCRAFT RECONNAISSANCE
FINDS ANA IS A TROPICAL STORM...WARNINGS WILL LIKELY BE REQUIRED
LATER TODAY. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/1500Z 14.8N  55.8W    35 KT
 12HR VT     17/0000Z 15.2N  58.7W    35 KT
 24HR VT     17/1200Z 16.1N  62.7W    40 KT
 36HR VT     18/0000Z 17.1N  66.7W    40 KT
 48HR VT     18/1200Z 18.3N  70.7W    45 KT
 72HR VT     19/1200Z 21.0N  77.5W    30 KT...INLAND
 96HR VT     20/1200Z 23.5N  83.0W    30 KT
120HR VT     21/1200Z 25.5N  85.5W    30 KT
 
$$
FORECASTER BRENNAN/ROBERTS
 

WTNT42 KNHC 162042
TCDAT2
TROPICAL DEPRESSION ANA DISCUSSION NUMBER  19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 PM AST SUN AUG 16 2009
 
AN AIR FORCE HURRICANE HUNTER AIRCRAFT INVESTIGATING ANA DID NOT
FIND ANY WINDS TO SUPPORT TROPICAL STORM INTENSITY. IN FACT...ALL
OF THE STRONG WINDS WERE WELL NORTH OF THE PRESSURE MINIMUM IN THE
EASTERLY TRADE WIND FLOW. THE INITIAL INTENSITY IS SET AT 30 KT FOR
THIS PACKAGE. THE AIRCRAFT ALSO STRUGGLED TO CLOSE OFF A
WELL-DEFINED CENTER...HOWEVER...WE WILL CONTINUE ADVISORIES FOR NOW
SINCE THE AIRCRAFT WILL STILL BE IN THE SYSTEM UNTIL 0000 UTC. IF
A WELL-DEFINED CENTER CANNOT BE FOUND AT THAT TIME...ADVISORIES MAY
BE DISCONTINUED.
 
ANA CONTINUES MOVING WESTWARD VERY QUICKLY...ALONG A HEADING OF
280/20. THIS QUICK MOTION IS EXPECTED TO CONTINUE THROUGH THE NEXT
COUPLE OF DAYS...WITH A GRADUAL TURN TOWARD THE WEST-NORTHWEST. THE
OFFICIAL FORECAST IS VERY CLOSE TO THE PREVIOUS PACKAGE...EXCEPT A
LITTLE FASTER TO ACCOUNT FOR THE QUICK INITIAL MOTION.
 
THE INTENSITY FORECAST SHOWS LITTLE CHANGE...WITH A POSSIBILITY FOR
SLIGHT STRENGTHENING PRIOR TO THE CYCLONE REACHING HISPANIOLA. AFTER
THAT TIME...THE INTENSITY IS HELD AT 30 KT GIVEN THE POTENTIAL FOR
LAND INTERACTION WITH HISPANIOLA AND CUBA.
 
TROPICAL STORM WATCHES ARE CONTINUED...GIVEN THAT THE CYCLONE IS NOT
FAR BELOW TROPICAL STORM STRENGTH AND APPROACHING THE ISLANDS SOON.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/2100Z 15.1N  58.8W    30 KT
 12HR VT     17/0600Z 15.7N  62.0W    30 KT
 24HR VT     17/1800Z 16.7N  66.1W    30 KT
 36HR VT     18/0600Z 17.8N  70.0W    35 KT
 48HR VT     18/1800Z 18.8N  73.6W    30 KT
 72HR VT     19/1800Z 21.5N  80.0W    30 KT
 96HR VT     20/1800Z 23.5N  84.5W    30 KT
120HR VT     21/1800Z 25.0N  87.0W    30 KT
 
$$
FORECASTER BRENNAN/ROBERTS
 

WTNT42 KNHC 170250
TCDAT2
TROPICAL DEPRESSION ANA DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 PM AST SUN AUG 16 2009
 
RADAR IMAGERY FROM GUADELOUPE SUGGESTS THAT THE LOW-LEVEL CENTER OF
ANA HAS TURNED TOWARD THE WEST-NORTHWEST AND IS MOVING QUICKLY AT
AN INITIAL MOTION OF 285/23.  ALTHOUGH SOME DEEP CONVECTION HAS
RECENTLY RE-DEVELOPED...IT IS ORIENTED LINEARLY ALONG A NORTH-SOUTH
AXIS AND APPEARS MORE REPRESENTATIVE OF A TROPICAL WAVE. THE CENTER
APPEARS REASONABLY WELL-DEFINED ON THE GUADELOUPE RADAR BUT THIS IS
LIKELY DEPICTING A MID-LEVEL CIRCULATION RATHER THAN ONE AT THE
SURFACE.  AT THIS TIME WE WOULD RATHER NOT STOP ADVISORIES WHILE
THE SYSTEM IS MOVING ACROSS THE LESSER ANTILLES.  HOWEVER IF
SURFACE OBSERVATIONS FROM THOSE ISLANDS CONFIRM THE LACK OF A
CENTER...ADVISORIES WILL BE TERMINATED EARLY MONDAY.
 
VERY FEW OF THE DYNAMICAL MODELS SHOW ANY RE-STRENGTHENING...AND A
FEW SUCH AS THE GFS...HWRF...AND GFDL LOSE THE VORTEX AFTER ABOUT
36 HOURS.  THE TRACK GUIDANCE INDICATES THAT ANA SHOULD BE MOVING
OVER THE HIGH TERRAIN OF HISPANIOLA IN 24-36 HOURS...AND IT IS
DOUBTFUL THAT ITS CIRCULATION WILL MAKE IT ACROSS THAT ISLAND
INTACT.  THE OFFICIAL FORECAST SHOWS ANA BECOMING A REMNANT LOW BY
36 HOURS AFTER IT BEGINS CROSSING LAND...BUT IT IS POSSIBLE THAT IT
COULD BECOME AN OPEN WAVE AT ANY TIME.  THE TRACK FORECAST IS
SHIFTED NORTH OF THE PREVIOUS FORECAST TOWARD THE SHALLOW LAYER BAM
TRACK AND IN LINE WITH THE GFS AND ECMWF SINCE IT IS ASSUMED THAT
THE REMNANT CIRCULATION WILL BE STEERED BY THE LOW-LEVEL FLOW.
 
TROPICAL STORM WATCHES WILL REMAIN IN EFFECT UNTIL IT IS CLEAR THAT
ANA WILL NOT RE-STRENGTHEN OR UNTIL IT PASSES THE LEEWARD ISLANDS
LATER TONIGHT.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0300Z 16.0N  61.2W    30 KT
 12HR VT     17/1200Z 16.7N  64.4W    30 KT
 24HR VT     18/0000Z 18.1N  68.6W    30 KT
 36HR VT     18/1200Z 19.6N  72.6W    25 KT...REMNANT LOW
 48HR VT     19/0000Z 21.2N  76.0W    25 KT...REMNANT LOW
 72HR VT     20/0000Z 24.0N  81.0W    25 KT...REMNANT LOW
 96HR VT     21/0000Z 26.0N  84.0W    25 KT...REMNANT LOW
120HR VT     22/0000Z 28.0N  86.0W    25 KT...REMNANT LOW
 
$$
FORECASTER BERG
 

WTNT42 KNHC 170849
TCDAT2
TROPICAL DEPRESSION ANA DISCUSSION NUMBER  21
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 AM AST MON AUG 17 2009
 
IT IS UNCLEAR IF ANA STILL HAS A CLOSED LOW-LEVEL WIND FIELD.  A
MID-LEVEL CIRCULATION IS NOTED IN RADAR IMAGERY FROM GUADELOUPE AND
SAN JUAN PUERTO RICO...BUT NO SURFACE OBSERVATIONS FROM THE
NORTHERN LEEWARD ISLANDS HAVE SHOWN A WESTERLY WIND COMPONENT.  IN
ADDITION...AN ASCAT PASS AROUND 0140 UTC STRONGLY SUGGESTED THAT
THE SYSTEM IS A SHARP TROPICAL WAVE.  BECAUSE OF THE RECENT
CONVECTIVE DEVELOPMENT...ADVISORIES ARE BEING CONTINUED FOR THE
DEPRESSION AT THIS TIME UNTIL VISIBLE SATELLITE IMAGERY CAN CONFIRM
OR DENY THE EXISTENCE OF A WELL-DEFINED LOW-LEVEL CENTER LATER THIS
MORNING.
 
ANA IS MOVING AT AN UNCERTAIN BUT FAST 285/24.  THE MODEL GUIDANCE
IS TIGHTLY CLUSTERED FOR THE NEXT 36 HOURS OR SO AND INDICATES THAT
ANA WILL MOVE OVER HISPANIOLA LATER TODAY.  THEREAFTER...MOST OF
THE DYNAMICAL GUIDANCE WEAKEN THE VORTEX AND BRING THE REMNANTS
TOWARD THE EASTERN GULF OF MEXICO OR FLORIDA BY DAYS 3 THROUGH
5...SIMILAR TO THE SHALLOW LAYER BAM TRACK.  THE OFFICIAL FORECAST
IS CLOSE TO THE MODEL CONSENSUS THROUGH 36 HOURS AND THEN SHOWS A
SLIGHT NORTHEASTWARD SHIFT THEREAFTER TOWARDS BAM SHALLOW SINCE THE
REST OF THE GUIDANCE LOSES THE VORTEX.  THIS FORECAST IS HIGHLY
UNCERTAIN AS IT IS ENTIRELY POSSIBLE THAT THE CIRCULATION MAY NOT
MAKE IT ACROSS HISPANIOLA INTACT.

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0900Z 16.6N  63.9W    30 KT
 12HR VT     17/1800Z 17.6N  67.2W    30 KT
 24HR VT     18/0600Z 19.3N  71.5W    25 KT...REMNANT LOW
 36HR VT     18/1800Z 21.2N  75.2W    25 KT...REMNANT LOW
 48HR VT     19/0600Z 22.8N  78.0W    25 KT...REMNANT LOW
 72HR VT     20/0600Z 25.5N  82.0W    25 KT...REMNANT LOW
 96HR VT     21/0600Z 28.0N  84.0W    25 KT...REMNANT LOW
120HR VT     22/0600Z 30.0N  84.5W    25 KT...REMNANT LOW
 
$$
FORECASTER BERG
 

WTNT42 KNHC 171500
TCDAT2
TROPICAL DEPRESSION ANA DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 AM AST MON AUG 17 2009
 
THE CENTER OR WAVE AXIS OF ANA PASSED OVER BUOY 42060 AROUND
0830Z...AND IF A CENTER EXISTED AT THAT TIME IT WAS SOUTH OF THE
BUOY.  THERE WAS ONE SHIP REPORT WITH A LIGHT WEST WIND AT 12Z. 
SINCE THAT TIME...NEW CONVECTION WITH A MID-LEVEL SPIN HAS
DEVELOPED NEAR THE SOUTHEAST COAST OF PUERTO RICO. GIVEN THESE
HINTS...WE WILL CONTINUE ADVISORIES AT LEAST UNTIL A RECONNAISSANCE
AIRCRAFT INVESTIGATES ANA THIS AFTERNOON.

WITH A CENTER POSITION ESTIMATE BASED ON A BLEND OF CONTINUITY AND
THE MID-LEVEL ROTATION SEEN IN THE RADAR DATA...THE INITIAL MOTION
IS 285/24. ANA IS EXPECTED TO CONTINUE ON A GENERAL WEST-
NORTHWESTWARD TRACK TO THE SOUTH OF THE SUBTROPICAL RIDGE FOR THE
NEXT COUPLE OF DAYS...ALTHOUGH SOME ERRATIC MOTION IS POSSIBLE IN
THE SHORT TERM GIVEN THE POOR DEFINITION OF THE CIRCULATION...
INTERACTION WITH LAND...AND POTENTIAL REFORMATION OF THE CENTER.
THE OFFICIAL FORECAST FOLLOWS A BLEND OF THE GFS AND ECMWF
SOLUTIONS FOR THE 850 MB VORTICITY CENTER. TOWARD THE END OF THE
FORECAST PERIOD...ANA OR ITS REMNANTS COULD BE EMBEDDED WITHIN WEAK
STEERING OVER OR NEAR THE GULF OF MEXICO...AND THE OFFICIAL
FORECAST CALLS FOR A GRADUAL SLOWING OF THE FORWARD SPEED.

THE INTENSITY FORECAST IS COMPLICATED BY THE UNCERTAIN EXISTENCE OF
AN ACTUAL TROPICAL CYCLONE...THE LAND MASSES IN THE PATH OF THE
SYSTEM...AND HIGHLY DIVERGENT OBJECTIVE GUIDANCE. THE ENVIRONMENT
OF ANA IS STILL CHARACTERIZED BY SOUTHWESTERLY SHEAR. THE DYNAMICAL
MODELS...BOTH GLOBAL AND REGIONAL...ALMOST UNANIMOUSLY DISSIPATE
THE CYCLONE...WHILE THE STATISTICAL MODELS SHOW RESTRENGHENING. IF
ANA SURVIVES ITS PATH OVER THE GREATER ANTILLES AND EMERGES TO THE
NORTH OF THE DOMINICAN REPUBLIC...THE GLOBAL MODELS SUGGEST THAT A
MORE FAVORABLE UPPER WIND PATTERN WILL BE PRESENT THERE.
CONSEQUENTLY...THE OFFICIAL FORECAST MAINTAINS ANA AS A TROPICAL
CYCLONE THROUGH THE FORECAST PERIOD. THIS IS...ADMITTEDLY...
SOMETHING OF A HEDGE BETWEEN TWO MORE LIKELY ALTERNATIVES...THAT OF
A TROPICAL STORM NORTH OF THE ISLANDS OR IMMINENT DISSIPATION. 


FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/1500Z 17.3N  66.2W    30 KT
 12HR VT     18/0000Z 18.6N  69.4W    30 KT...INLAND
 24HR VT     18/1200Z 20.5N  73.7W    30 KT
 36HR VT     19/0000Z 22.3N  77.0W    30 KT
 48HR VT     19/1200Z 23.7N  79.4W    30 KT
 72HR VT     20/1200Z 26.5N  82.5W    30 KT
 96HR VT     21/1200Z 28.0N  83.0W    30 KT
120HR VT     22/1200Z 30.0N  83.0W    25 KT...INLAND
 
$$
FORECASTER FRANKLIN/CANGIALOSI
 

WTNT42 KNHC 172041
TCDAT2
TROPICAL DEPRESSION ANA DISCUSSION NUMBER  23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
500 PM AST MON AUG 17 2009
 
AN AIR FORCE RECONNAISSANCE AIRCRAFT INVESTIGATED ANA THIS AFTERNOON
AND DID NOT FIND A CLOSED WIND CIRCULATION. CONSEQUENTLY...ANA IS
NO LONGER A TROPICAL CYCLONE AND THIS WILL BE THE LAST ADVISORY ON
THIS SYSTEM UNLESS REGENERATION OCCURS. 

THE REMNANTS OF ANA ARE MOVING AT 290/21. THE REMNANT TROUGH IS
EXPECTED TO CONTINUE ON THIS PATH...BRINGING THE THREAT FOR HEAVY
RAINFALL AND GUSTY WINDS TO HISPANIOLA AND CUBA OVER THE NEXT
COUPLE OF DAYS. GFS AND ECMWF SOLUTIONS HAVE BOTH SHIFTED SOUTH
FROM EARLIER...TAKING THE 850 MB VORTICITY CENTER OVER OR EVEN
SOUTH OF CUBA...LIMITING THE CHANCES OF REGENERATION.  

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/2100Z 17.5N  68.0W    30 KT
 12HR VT     18/0600Z...DISSIPATED
 
$$
FORECASTER CANGIALOSI/FRANKLIN
 

