Tropical Depression NINETEEN

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TROPICAL DEPRESSION NINETEEN DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
5 AM EDT TUE OCT 14 2003
 
TROPICAL DEPRESSION NINETEEN HAS CHANGED LITTLE OVERNIGHT. WHILE
CONVECTIVE TOPS HAVE WARMED...THE OVERALL CONVECTIVE PATTERN HAS
BECOME A LITTLE BETTER ORGANIZED WITH THE CONVECTION HAVING
DEVELOPED CLOSER AND POSSIBLY OVER THE LOW-LEVEL CENTER. THE
INITIAL INTENSITY IS BEING MAINTAINED AT 30 KT BASED ON A DVORAK
INTENSITY ESTIMATE OF T2.0/30 KT FROM ALL THREE AGENCIES.
 
THE INITIAL POSITION AND MOTION ESTIMATE OF 285/08 IS BASED ON
CONTINUITY WITH THE PREVIOUS 6-HR MOTION AND FORECAST TRACK. THE
NHC MODEL GUIDANCE IS SPREAD ALL OVER THE COMPASS IN THE NORTHERN
SEMICIRCLE. THE NOGAPS MODEL IS THE EASTERNMOST OF THE MODELS AND
TAKES THE DEPRESSION ALMOST DUE NORTH AND THEN NORTHEASTWARD FROM
ITS CURRENT POSITON...WHICH SEEMS HIGHLY UNLIKELY AND WAS THEREFORE
IGNORED. THE GFS MODEL DEVELOPS WHAT APPEARS TO BE A BOGUS TROPICAL
STORM IN 36-48 HOURS TO THE EAST OF TD-19...WHICH ACTS TO PULL THE
DEPRESSION NORTHEASTWARD BY 48 HOURS...AND THIS UNLIKELY SCENARIO
WAS ALSO DISCOUNTED. THE REMAINING MODEL GUIDANCE CONSISTS OF THE
UKMET AND GFDL MODELS...WHICH TAKE TD-19 NORTHWESTWARD FROM ITS
CURRENT POSTION FOR THE NEXT 72 HOURS AND THEN TURN IT SLOWLY
NORTHWARD AFTER THAT. THE THREE BAM MODELS AND THE LBAR MODEL TAKE
TD-19 BASICALLY WEST-NORTHWESTWARD. THE FUTURE TRACK OF TD-19
DEPENDS HEAVILY ON WHAT EFFECT THE DIGGING TROUGH TO THE NORTH WILL
HAVE ON THE NARROW AND WEAK SUBTROPICAL RIDGE THAT HAS BEEN
STEERING THE DEPRESSION WESTWARD. THE TROUGH AXIS IS ALREADY ALONG
THE SAME LONGITUDE AS TD-19 AND IT IS FORECAST TO CONTINUE MOVING
EASTWARD...PERHAPS BYPASSING THE CYCLONE. AS SUCH... THE OFFICIAL
FORECAST TRACK IS TO THE LEFT OF THE PREVIOUS TRACK AND IS CLOSE TO
A BLEND OF THE GFS...GFDL...AND THE BAM MODELS. IT SHOULD BE NOTED
THAT THE CANADIAN MODEL MAINTAINS THE RIDGE TO THE NORTH THROUGHOUT
THE FORECAST PERIOD AND HAS TD-19 NEAR THE NORTHERN LEEWARD ISLANDS
IN 120 HOURS. THIS IS CERTAINLY A VIABLE FORECAST POSSIBILITY IF
THE CYCLONE DOES NOT MOVED NORTHWARD BY 48 HOURS.

SOME UPPER-LEVEL SOUTH TO SOUTHWESTERLY SHEAR IS FORECAST TO REMAIN
ON THE DEPRESSION THROUGH AT LEAST THE NEXT 48-72 HOURS...SO ONLY
MODEST STRENGTHENING IS FORECAST. THIS IS BELOW THE SHIPS MODEL AND
WELL BELOW THE GFDL MODEL FORECASTS...WHICH BRING THE CYCLONE UP TO
72 KT IN 72 HOURS AND 95 KT IN 60 HOURS...RESPECTIVELY.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/0900Z 10.1N  40.5W    30 KT
 12HR VT     14/1800Z 10.4N  41.6W    35 KT
 24HR VT     15/0600Z 10.9N  43.0W    40 KT
 36HR VT     15/1800Z 11.4N  44.1W    45 KT
 48HR VT     16/0600Z 12.0N  45.0W    50 KT
 72HR VT     17/0600Z 13.0N  45.7W    55 KT
 96HR VT     18/0600Z 15.0N  46.0W    65 KT
120HR VT     19/0600Z 17.5N  46.0W    65 KT
 
 
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