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TROPICAL STORM DOLLY DISCUSSION NUMBER   3
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT THU AUG 29 2002

DOLLY IS PRESENTING AN INCREASINGLY IMPRESSIVE APPEARANCE THIS
EVENING WITH A LARGE AREA OF COLD CONVECTIVE TOPS IN A LOOSE BAND
OVER THE WESTERN SEMICIRCLE OF THE CIRCULATION.  SATELLITE
INTENSITY ESTIMATES ARE 45 KT FROM SAB...35 KT FROM TAFB...AND
30 KT FROM AFWA.  BASED ON THESE AND THE IMPROVED APPEARANCE
SINCE THE PREVIOUS ADVISORY...THE MAXIMUM WINDS ARE RAISED TO
40 KT.
 
THERE IS THE USUAL UNCERTAINTY OF FINDING THE CENTER TONIGHT...WITH
THE IR-BASED FIXES COMING IN A LITTLE TO THE SOUTH...AND QUIKSCAT
AND SSM/I DATA SUGGESTING AN ELONGATED CENTER A LITTLE FURTHER
NORTH.  THE SYNOPTIC AND ADVISORY POSITIONS SOMEWHAT COMPROMISE
BETWEEN THE EXTREMES AND PRODUCE AN INITIAL MOTION OF 270/11.
DOLLY IS SOUTH OF A LOW/MID LEVEL RIDGE...WHICH SHOULD MORE OR LESS
CONTINUE THROUGH THE FORECAST PERIOD AND KEEP DOLLY ON A WESTWARD
OR WEST-NORTHWESTWARD TRACK.  THE BIG QUESTIONS ARE HOW STRONG WILL
THE RIDGE BE IN 48-72 HR AND JUST HOW FAR NORTH WILL DOLLY GO.
TRACK GUIDANCE IS SPLIT INTO TWO CAMPS.  THE FIRST...WHICH INCLUDES
THE UKMET...NOGAPS...AND GFDL...CALLS FOR A WEST-NORTHWESTWARD
MOTION THROUGH THE FORECAST PERIOD.  THE SECOND CAMP...WHICH
INCLUDES THE BAM MODELS...NHC98...AND LBAR...CALLS FOR A WESTWARD
MOTION FOR 24 HR FOLLOWED BY A GRADUAL TURN TO THE WEST-NORTHWEST.
THE GLOBAL MODELS ALL HAD POOR INITIALIZATIONS OF DOLLY AND THERE
IS NO OBVIOUS SIGN OF ANY TURN YET.  THUS...THE OFFICIAL FORECAST
WILL FOLLOW THE MORE WESTWARD MODELS AND IS IN BEST AGREEMENT WITH
NHC98 AND CLIPER. 
 
DOLLY IS CURRENTLY IN A LIGHT SHEAR ENVIRONMENT AND SHOWS FAIR TO
GOOD OUTFLOW IN ALL DIRECTIONS EXCEPT EASTWARD.  THERE IS NO
OBVIOUS REASON FOR IT NOT TO STRENGTHEN IN THE SHORT TERM...AND
THE INTENSITY FORECAST REFLECTS THIS.  IN THE LONG TERM...ALL 
LARGE-SCALE MODELS DEVELOP AN UPPER-LEVEL TROUGH NORTHEAST OF THE 
LESSER ANTILLES BY 72 HR AND DEVELOP UNFAVORABLE WESTERLIES NORTH
OF 15N-17N. SHOULD DOLLY VEER MORE NORTHWARD...IT WOULD ENCOUNTER
THESE WINDS...WHICH WOULD STOP INTENSIFICATION AND POSSIBLY WEAKEN
THE STORM.  ON THE OTHER HAND...A MORE SOUTHERLY TRACK WOULD BE
THROUGH A MORE FAVORABLE ENVIRONMENT AND ALLOW MORE STRENGTHENING.
THE INTENSITY FORECAST WILL COMPROMISE BETWEEN THESE EXTREMES...
TAKING DOLLY TO JUST UNDER HURRICANE STRENGTH IN 48-72 HR.  IT
SHOULD BE NOTED THAT THE SHIPS MODEL FORECASTS SHEAR TO BE 10 KT
OR LESS ALONG THE FORECAST TRACK THROUGH 72 HR.  SHOULD THIS
VERIFY...DOLLY COULD STRENGTHEN MORE THAN CURRENTLY FORECAST.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     30/0300Z  9.7N  33.7W    40 KTS
12HR VT     30/1200Z  9.7N  35.5W    45 KTS
24HR VT     31/0000Z 10.0N  38.0W    50 KTS
36HR VT     31/1200Z 10.5N  40.3W    55 KTS
48HR VT     01/0000Z 11.1N  42.8W    60 KTS
72HR VT     02/0000Z 12.5N  47.0W    60 KTS
 
 
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