Tropical Depression NINETEEN

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TROPICAL DEPRESSION NINETEEN DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT FRI SEP 30 2005
 
AN SSM/IS OVERPASS AT 2227Z INDICATED THAT THE LOW-LEVEL CENTER OF
TROPICAL DEPRESSION NINETEEN WAS EXPOSED TO THE NORTH OF STRONG AND
PERSISTENT CONVECTION.  SHORTWAVE IMAGERY FROM METEOSAT-8 SINCE
THAT TIME SUGGESTS THIS IS STILL THE CASE...BUT IT CANNOT BE
DETERMINED JUST HOW FAR THE CENTER IS FROM THE CONVECTION AT THE
MOMENT.  SATELLITE INTENSITY ESTIMATES ARE 30 KT FROM TAFB AND
SAB...AND 25 KT FROM AFWA.  THE INITIAL INTENSITY IS INCREASED TO
30 KT.

THE INITIAL MOTION IS A RATHER UNCERTAIN 310/2.  OTHER THAN THAT...
THERE IS LITTLE CHANGE IN THE FORECAST PHILOSOPHY FROM THE PREVIOUS
ADVISORY.  A DEEP LAYER LOW PRESSURE SYSTEM CENTERED ABOUT 700 N MI
NORTH OF THE DEPRESSION IS FORECAST TO MOVED WESTWARD FOR THE NEXT
FEW DAYS...WHICH SHOULD CAUSE THE DEPRESSION TO MOVE IN A GENERAL
NORTHWESTWARD OR NORTHWARD DIRECTION FOR 72-96 HR.  THE TRACK
GUIDANCE GENERALLY AGREES WITH THIS ALTHOUGH THERE IS SOME SPREAD
BETWEEN THE MORE WESTWARD GFS AND THE MORE EASTWARD NOGAPS.  THE
TRACK FORECAST THROUGH 96 HR IS DOWN THE MIDDLE OF THE ENVELOPE OF
DYNAMICAL GUIDANCE.  AFTER 96 HR...THE LARGE-SCALE MODELS SUGGEST A
LOW/MID-LEVEL RIDGE MAY FORM NORTH OF THE CYCLONE...WHICH COULD
STEER IT MORE WESTWARD.  THE FORECAST TRACK WILL NOT SHOW THIS
YET...BUT WILL SLOW THE SYSTEM DOWN IN RESPONSE TO THIS
POSSIBILITY.
 
THE DEPRESSION IS CURRENTLY EXPERIENCING 15-20 KT OF NORTHERLY OR
NORTHWESTERLY VERTICAL SHEAR...ALTHOUGH THIS NOT STOPPING THE
CONVECTION THUS FAR.  THE SHIPS MODEL FORECASTS DECREASING SHEAR IN
ABOUT 12 HR AND MAINTAINS THIS THROUGH ABOUT 60 HR.  THIS SHOULD
ALLOW THE CYCLONE TO STRENGTHEN...AND THE INTENSITY FORECAST CALLS
FOR A PEAK INTENSITY OF 50 KT IN 48-72 HR.  THIS IS A BIT LESS THAN
EITHER THE SHIPS OR GFDL ARE FORECASTING.  THE LARGE-SCALE MODELS
ARE FORECASTING SIGNIFICANT SOUTHWESTERLY SHEAR ON THE SOUTH AND
SOUTHEAST SIDE OF THE DEEP-LAYER LOW...AND IF THE DEPRESSION GETS
TOO CLOSE TO THAT THE SHEAR WILL BE MUCH STRONGER THAN SHIPS IS
FORECASTING.  THUS...THE INTENSITY FORECAST WILL REMAIN ON THE
CONSERVATIVE SIDE UNTIL IT IS MORE APPARENT THAT THE CYCLONE WILL
STAY SOUTH OF THE STRONGER SHEAR.
 
FORECASTER BEVEN
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      01/0300Z 12.3N  33.1W    30 KT
 12HR VT     01/1200Z 12.5N  33.3W    35 KT
 24HR VT     02/0000Z 13.0N  33.9W    40 KT
 36HR VT     02/1200Z 14.2N  34.6W    45 KT
 48HR VT     03/0000Z 15.8N  35.2W    50 KT
 72HR VT     04/0000Z 19.5N  36.5W    50 KT
 96HR VT     05/0000Z 23.5N  36.5W    45 KT
120HR VT     06/0000Z 26.5N  36.5W    45 KT
 
 
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