Tropical Depression NINETEEN

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TROPICAL DEPRESSION NINETEEN DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT SAT OCT 01 2005
 
TROPICAL DEPRESSION NINETEEN IS FEELING THE EFFECTS OF WESTERLY
SHEAR THIS EVENING.  THE LOW-LEVEL CENTER IS PARTLY EXPOSED BETWEEN
CONVECTIVE CLUSTERS TO THE NORTHEAST AND SOUTHWEST.  SATELLITE
INTENSITY ESTIMATES REMAIN 35 KT FROM TAFB AND SAB.  HOWEVER...A
QUIKSCAT OVERPASS SHOW NO WINDS HIGHER THAN 25 KT THAT WERE NOT IN
THE CONVECTIVE CLUSTERS.  BLENDING THESE DATA PRODUCES AN INITIAL
INTENSITY OF 30 KT.

THE INITIAL MOTION IS 350/6.  A LARGE-DEEP LAYER LOW NORTH OF THE
DEPRESSION IS FORECAST TO MOVE WESTWARD FOR THE NEXT 3-4 DAYS...
ALLOWING THE DEPRESSION TO MOVE GENERALLY NORTH-NORTHWESTWARD TO
NORTHWARD ON THE EAST SIDE OF THE LOW.  AFTER THAT...THE FORECAST
BECOME MORE UNCERTAIN.  MUCH OF THE GUIDANCE WANTS TO TURN THE
CYCLONE EASTWARD AFTER 72 HR EVEN THOUGH THE MODEL MASS FIELDS
INDICATE RIDGING NORTH OF THE DEPRESSION.  BASED ON THE RIDGING...
THE FORECAST TRACK WILL CALL FOR A MUCH SLOWER NORTHEASTWARD TURN
THAT THAT CURRENTLY CALLED FOR BY THE GUIDANCE.
 
THE BIG QUESTION IS HOW LONG WILL THE SYSTEM SURVIVE?  ALL THE
LARGE-SCALE MODELS FORECAST SIGNIFICANT SOUTHWESTERLY TO WESTERLY
SHEAR THROUGH THE FORECAST PERIOD...PARTICULARLY NORTH OF 20N WHERE
IT IS FORECAST TO BE IN EXCESS OF 40 KT AND THE SEA SURFACE
TEMPERATURES ARE BARELY 26C.  BASED ON THIS...THE INTENSITY
FORECAST IS LOWERED SLIGHTLY FROM THE PREVIOUS ADVISORY.  THE
FORECAST CALLS FOR SOME SLIGHT STRENGTHENING DURING THE NEXT 24 HR
IN CASE SOME TEMPORARY DECREASE IN THE SHEAR OCCURS OR A STRONG
CONVECTIVE BURST SPINS THE SYSTEM UP.  IT THEN CALLS FOR THE SYSTEM
TO WEAKEN AS THE SHEAR INCREASES...BECOMING A REMNANT LOW BY 120
HR.  IT IS POSSIBLE GIVEN CURRENT TRENDS THAT THE DEPRESSION MAY
NOT STRENGTHEN AT ALL...AND DISSIPATE SOONER THAN CURRENTLY
FORECAST.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/0300Z 15.3N  34.0W    30 KT
 12HR VT     02/1200Z 16.6N  34.4W    30 KT
 24HR VT     03/0000Z 18.2N  35.3W    35 KT
 36HR VT     03/1200Z 19.9N  36.0W    35 KT
 48HR VT     04/0000Z 22.0N  36.4W    30 KT
 72HR VT     05/0000Z 25.0N  36.5W    25 KT
 96HR VT     06/0000Z 27.5N  36.0W    25 KT...DISSIPATING
120HR VT     07/0000Z 29.5N  34.0W    20 KT...REMNANT LOW
 
 
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