WTNT45 KNHC 131441
TCDAT5
TROPICAL DEPRESSION FIFTEEN DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
1100 AM EDT MON OCT 13 2008
 
THE AREA OF LOW PRESSURE OVER THE EASTERN CARIBBEAN SEA HAS
DEVELOPED ENOUGH CIRCULATION AND DEEP CONVECTION TO BE CLASSIFIED
AS A TROPICAL DEPRESSION. NORMALLY...I WOULD WAIT FOR THE
RECONNAISSANCE PLANE WHICH IN FACT IS SCHEDULE FOR THIS AFTERNOON TO
START ADVISORIES...BUT IN THIS CASE...THERE ARE DATA SUPPORTING THE
PRESENCE OF A TROPICAL DEPRESSION.  THE CYCLONIC CIRCULATION CAN BE
DEPICTED ON THE CURACAO RADAR...SURFACE OBSERVATIONS..CLOUD WIND
VECTORS AND ON THE LATEST QUIKSCAT PASS THIS MORNING. INITIAL
INTENSITY IS 30 KNOTS BASED ON DVORAK CLASSIFICATIONS AND QUIKSCAT.
THE DEPRESSION IS NOT EMBEDDED IN THE BEST ENVIRONMENT FOR
STRENGTHENING SINCE THERE IS SOUTHWESTERLY SHEAR...BUT IS FAVORABLE
ENOUGH TO ALLOW THE CYCLONE TO REACH TROPICAL STORM INTENSITY IN 12
TO 24 HOURS. THEREAFTER...THE SHEAR IS FORECAST TO INCREASE SOME
MAKING THE INTENSITY FORECAST HIGHLY UNCERTAIN. AT THIS TIME...THE
OFFICIAL FORECAST IS A BLEND OF THE STATISTICAL MODEL SHIPS AND THE
DYNAMICAL MODELS GFDL AND HWRF. IN FACT...THE GFDL AND HWRF
FORECAST THE DEPRESSION TO BE A HURRICANE AS IT MOVES NEAR
PUERTO RICO.
  
THE DEPRESSION IS EMBEDDED WITHIN LIGHT STEERING CURRENTS AND IS
DRIFTING NORTHWESTWARD. SINCE NO CHANGE IN STEERING IS EXPECTED FOR
A DAY OR TWO...NO SIGNIFICANT MOTION IS ANTICIPATED DURING THAT
PERIOD. THEREAFTER...GLOBAL MODELS DEVELOP A LARGE AND STRONG MID-
LATITUDE TROUGH OVER THE WESTERN ATLANTIC. THE CYCLONE IS EXPECTED
TO BECOME EMBEDDED WITHIN THE SOUTHWESTERLY FLOW AHEAD OF THIS
TROUGH AND RECURVE. THIS TRACK SHOULD BRING THE CYCLONE VERY CLOSE
TO PUERTO RICO BETWEEN 48 AND 72 HOURS AND OVER THE OPEN ATLANTIC
THEREAFTER. THIS TRACK IS VERY CLOSE TO THE MODEL CONSENSUS AND
ALSO IS HEAVILY BIASED TOWARD THE GFDL AND HWRF MODELS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/1500Z 14.8N  69.6W    30 KT
 12HR VT     14/0000Z 15.1N  70.0W    35 KT
 24HR VT     14/1200Z 15.5N  70.0W    45 KT
 36HR VT     15/0000Z 16.0N  69.0W    50 KT
 48HR VT     15/1200Z 17.0N  67.5W    55 KT
 72HR VT     16/1200Z 20.0N  63.5W    65 KT
 96HR VT     17/1200Z 24.0N  59.5W    65 KT
120HR VT     18/1200Z 30.0N  55.0W    65 KT
 
$$
FORECASTER AVILA
 

WTNT45 KNHC 132037
TCDAT5
TROPICAL DEPRESSION FIFTEEN DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
500 PM EDT MON OCT 13 2008
 
THE DEPRESSION HAS NOT CHANGED SIGNIFICANTLY IN ORGANIZATION DURING
THE DAY AND THE APPARENT CENTER HAS BEEN AT TIMES EXPOSED DUE TO
SHEAR. THERE ARE SOME INDICATIONS THAT THE CIRRUS CLOUDS ARE
EXPANDING WESTWARD SUGGESTING THAT THE SHEAR IS RELAXING A BIT.
SURFACE OBSERVATIONS FROM THE CARIBBEAN INDICATE THAT THERE IS A
LARGE CIRCULATION ASSOCIATED WITH THE CYCLONE.  A RECONNAISSANCE
PLANE IS SCHEDULED TO BE IN THE DEPRESSION SHORTLY.  NO SIGNIFICANT
CHANGE FROM THE PREVIOUS INTENSITY FORECAST IS INDICATED AND IT
CONTINUES TO BE A BLEND OF THE SHIPS MODEL AND THE GFDL/HWRF MODEL
PAIR. THE LATTER MODELS MAKE THE DEPRESSION A HURRICANE AS IT MOVES
NEAR PUERTO RICO.  

THE DEPRESSION IS EMBEDDED WITHIN VERY LIGHT STEERING CURRENTS AND
LITTLE MOTION IS INDICATED FOR THE NEXT DAY OR SO. THEREAFTER...
GLOBAL MODELS CONTINUE TO SHOW THE DEVELOPMENT OF A LARGE AND
STRONG MID-LATITUDE TROUGH OVER THE WESTERN ATLANTIC. THE
SOUTHWESTERLY FLOW AHEAD OF THIS TROUGH SHOULD FORCE THE CYCLONE TO
RECURVE AND MOVE TOWARD THE NORTHEAST WITH INCREASING FORWARD
SPEED.  ON THIS TRACK...THE CYCLONE WILL BE NEAR PUERTO RICO IN
ABOUT 48 HOURS AND THEN OVER THE ATLANTIC OCEAN. ALTHOUGH A
FORECAST POSITION IS INDICATED AT 120 HOURS OVER THE ATLANTIC...
THERE IS A POSSIBILITY THE CYCLONE WILL BECOME ABSORBED BY
A LARGE EXTRATROPICAL STORM BY THAT TIME.  THIS OFFICIAL FORECAST
FOLLOWS THE MODEL CONSENSUS AND IS IN THE MIDDLE OF THE GUIDANCE
ENVELOPE DURING THE FIRST 3 DAYS.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      13/2100Z 14.8N  69.9W    30 KT
 12HR VT     14/0600Z 14.9N  69.9W    40 KT
 24HR VT     14/1800Z 15.5N  69.5W    45 KT
 36HR VT     15/0600Z 16.5N  68.4W    50 KT
 48HR VT     15/1800Z 17.7N  66.6W    55 KT
 72HR VT     16/1800Z 20.0N  63.5W    65 KT
 96HR VT     17/1800Z 23.5N  59.5W    60 KT
120HR VT     18/1800Z 27.5N  56.0W    50 KT
 
$$
FORECASTER AVILA
 

WTNT45 KNHC 140252
TCDAT5
TROPICAL DEPRESSION FIFTEEN DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
1100 PM EDT MON OCT 13 2008
 
THE RECONNAISSANCE AIRCRAFT INVESTIGATING THE TROPICAL DEPRESSION
FOUND PEAK FLIGHT-LEVEL WINDS OF 34 KT FROM 925 MB...WHICH DOES NOT
SUPPORT AN UPGRADE TO A TROPICAL STORM.  THERE WERE SFMR WINDS OF
TROPICAL STORM FORCE...BUT IN RAINY CONDITIONS THIS WIND SPEED
RANGE IS NOT WHERE THE INSTRUMENT PERFORMS BEST.  THE CENTER OF
CIRCULATION IS ON THE WESTERN EDGE OF THE DEEP CONVECTION WITH SOME
WESTERLY SHEAR STILL EVIDENT IN INFRARED AND WATER VAPOR IMAGERY. 
WITH THE EXCEPTION OF THE GFS...ALL AVAILABLE GUIDANCE INDICATES
THAT THE CYCLONE SHOULD BE ABLE TO STRENGTHEN IN WHAT SHOULD BE A
MODERATE SHEAR ENVIRONMENT OVER THE NEXT FEW DAYS...WITH THE GFDL
AND HWRF BOTH MAKING THE SYSTEM A HURRICANE BEFORE IT EXITS THE
CARIBBEAN.  THE OFFICIAL FORECAST IS CLOSE TO THE CONSENSUS OF THE
INTENSITY GUIDANCE.  

THERE IS VERY LITTLE SURROUNDING MID-LEVEL FLOW AND THE DEPRESSION
IS ESSENTIALLY STATIONARY.  A LARGE UPPER-LOW EAST OF NEW ENGLAND
IS DRIVING SOUTHWARD IN THE WESTERN ATLANTIC...AND THIS FEATURE IS
EXPECTED TO BEGIN LIFTING THE TROPICAL CYCLONE NORTHEASTWARD IN
ANOTHER 24-36 HOURS.  COMPARED TO SIX HOURS AGO THE GUIDANCE HAS
SHIFTED WESTWARD...WITH SOME UNCERTAINTY AS TO WHETHER THE CYCLONE
WILL BE CAPTURED BY THE UPPER LOW.  A MAJORITY OF THE MODELS NOW
SHOW THE CYCLONE BEING LEFT BEHIND BY THIS FEATURE.  THE OFFICIAL
FORECAST HAS BEEN SHIFTED TO THE LEFT AT THE LONGER RANGES AND IS
IN BEST AGREEMENT WITH THE ECMWF.  THE HWRF AND GFDL ARE MUCH
SLOWER BRINGING THE SYSTEM OUT OF THE CARIBBEAN AND CONSEQUENTLY
ARE EVEN FARTHER TO THE LEFT.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/0300Z 14.6N  69.4W    30 KT
 12HR VT     14/1200Z 14.8N  69.2W    40 KT
 24HR VT     15/0000Z 15.5N  68.6W    45 KT
 36HR VT     15/1200Z 16.5N  67.4W    50 KT
 48HR VT     16/0000Z 18.0N  66.0W    55 KT
 72HR VT     17/0000Z 21.0N  63.0W    65 KT
 96HR VT     18/0000Z 24.0N  60.0W    65 KT
120HR VT     19/0000Z 29.0N  58.0W    65 KT
 
$$
FORECASTER FRANKLIN
 

WTNT45 KNHC 140832
TCDAT5
TROPICAL DEPRESSION FIFTEEN DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
500 AM EDT TUE OCT 14 2008

ALTHOUGH DVORAK INTENSITY ESTIMATES HAVE BEEN SUGGESTING THAT THE
SYSTEM IS NEAR TROPICAL STORM STRENGTH...SATELLITE IMAGES INDICATE
THAT THE CYCLONE HAS NOT BECOME SIGNIFICANTLY BETTER ORGANIZED
SINCE THE RECONNAISSANCE AIRCRAFT DEPARTED THE AREA.  THEREFORE THE
CURRENT INTENSITY IS HELD AT 30 KT FOR THIS PACKAGE.  THE
CIRCULATION CENTER APPEARS TO BE NEAR THE NORTHWEST SIDE OF THE
DEEP CONVECTION...INDICATIVE OF NORTHWESTERLY SHEAR ON THE SYSTEM. 
GLOBAL MODELS INDICATE MODERATELY STRONG VERTICAL SHEAR WILL
CONTINUE TO IMPACT THE CYCLONE OVER THE NEXT SEVERAL DAYS. 
NONETHELESS THE CONSENSUS OF DYNAMICAL AND STATISTICAL/DYNAMICAL
GUIDANCE INDICATES THAT THE SHEAR WILL NOT BE STRONG ENOUGH TO
PREVENT SOME INTENSIFICATION.  THE OFFICIAL WIND SPEED FORECAST IS
VERY CLOSE TO THIS CONSENSUS. 

THE DEPRESSION HAS BEEN DRIFTING SOUTHEASTWARD...OR 130/2. 
OBVIOUSLY THE STEERING WINDS OVER THE EASTERN CARIBBEAN ARE VERY
WEAK AT THIS TIME.  OVER THE NEXT FEW DAYS...THE GLOBAL MODELS SHOW
A MID-TROPOSPHERIC TROUGH DEEPENING TO THE NORTH OF THE TROPICAL
CYCLONE AND A RIDGE BUILDING TO ITS EAST.  THESE DEVELOPMENTS
SHOULD CAUSE THE CYCLONE TO TURN EASTWARD AND NORTHEASTWARD WITH A
GRADUAL INCREASE IN FORWARD SPEED.  THE OFFICIAL TRACK FORECAST IS
VERY SIMILAR TO THE PREVIOUS ONE...AND IS ALSO QUITE CLOSE TO THE
DYNAMICAL MODEL CONSENSUS.

RADAR IMAGES FROM CURACAO SHOW RAIN BANDS ASSOCIATED WITH THE
DEPRESSION PASSING OVER THE NETHERLANDS ANTILLES AND LOCALLY HEAVY
RAINS ARE LIKELY TO CONTINUE OVER PORTIONS OF THESE ISLANDS TODAY.  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/0900Z 14.3N  69.2W    30 KT
 12HR VT     14/1800Z 14.6N  68.9W    40 KT
 24HR VT     15/0600Z 15.3N  68.3W    45 KT
 36HR VT     15/1800Z 16.6N  67.1W    50 KT
 48HR VT     16/0600Z 18.3N  65.5W    55 KT
 72HR VT     17/0600Z 21.6N  62.5W    65 KT
 96HR VT     18/0600Z 26.0N  59.0W    65 KT
120HR VT     19/0600Z 31.0N  57.0W    65 KT
 
$$
FORECASTER PASCH
 

WTNT45 KNHC 140832
TCDAT5
TROPICAL DEPRESSION FIFTEEN DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL152008
500 AM EDT TUE OCT 14 2008

ALTHOUGH DVORAK INTENSITY ESTIMATES HAVE BEEN SUGGESTING THAT THE
SYSTEM IS NEAR TROPICAL STORM STRENGTH...SATELLITE IMAGES INDICATE
THAT THE CYCLONE HAS NOT BECOME SIGNIFICANTLY BETTER ORGANIZED
SINCE THE RECONNAISSANCE AIRCRAFT DEPARTED THE AREA.  THEREFORE THE
CURRENT INTENSITY IS HELD AT 30 KT FOR THIS PACKAGE.  THE
CIRCULATION CENTER APPEARS TO BE NEAR THE NORTHWEST SIDE OF THE
DEEP CONVECTION...INDICATIVE OF NORTHWESTERLY SHEAR ON THE SYSTEM. 
GLOBAL MODELS INDICATE MODERATELY STRONG VERTICAL SHEAR WILL
CONTINUE TO IMPACT THE CYCLONE OVER THE NEXT SEVERAL DAYS. 
NONETHELESS THE CONSENSUS OF DYNAMICAL AND STATISTICAL/DYNAMICAL
GUIDANCE INDICATES THAT THE SHEAR WILL NOT BE STRONG ENOUGH TO
PREVENT SOME INTENSIFICATION.  THE OFFICIAL WIND SPEED FORECAST IS
VERY CLOSE TO THIS CONSENSUS. 

THE DEPRESSION HAS BEEN DRIFTING SOUTHEASTWARD...OR 130/2. 
OBVIOUSLY THE STEERING WINDS OVER THE EASTERN CARIBBEAN ARE VERY
WEAK AT THIS TIME.  OVER THE NEXT FEW DAYS...THE GLOBAL MODELS SHOW
A MID-TROPOSPHERIC TROUGH DEEPENING TO THE NORTH OF THE TROPICAL
CYCLONE AND A RIDGE BUILDING TO ITS EAST.  THESE DEVELOPMENTS
SHOULD CAUSE THE CYCLONE TO TURN EASTWARD AND NORTHEASTWARD WITH A
GRADUAL INCREASE IN FORWARD SPEED.  THE OFFICIAL TRACK FORECAST IS
VERY SIMILAR TO THE PREVIOUS ONE...AND IS ALSO QUITE CLOSE TO THE
DYNAMICAL MODEL CONSENSUS.

RADAR IMAGES FROM CURACAO SHOW RAIN BANDS ASSOCIATED WITH THE
DEPRESSION PASSING OVER THE NETHERLANDS ANTILLES AND LOCALLY HEAVY
RAINS ARE LIKELY TO CONTINUE OVER PORTIONS OF THESE ISLANDS TODAY.  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/0900Z 14.3N  69.2W    30 KT
 12HR VT     14/1800Z 14.6N  68.9W    40 KT
 24HR VT     15/0600Z 15.3N  68.3W    45 KT
 36HR VT     15/1800Z 16.6N  67.1W    50 KT
 48HR VT     16/0600Z 18.3N  65.5W    55 KT
 72HR VT     17/0600Z 21.6N  62.5W    65 KT
 96HR VT     18/0600Z 26.0N  59.0W    65 KT
120HR VT     19/0600Z 31.0N  57.0W    65 KT
 
$$
FORECASTER PASCH
 

