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TROPICAL STORM DOLLY DISCUSSION NUMBER  23
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT TUE SEP 03 2002
 
THE INITIAL INTENSITY REMAINS A VERY GENEROUS 45 KT BASED ON 
SATELLITE INTENSITY ESTIMATES OF 45 KT FROM TAFB AND AFWA...AND 
55 KT FROM SAB. HOWEVER...SATELLITE IMAGERY DURING PAST 3 HOURS 
INDICATES THE CONVECTION HAS WEAKENED AND THE LOW-LEVEL CENTER HAS 
BECOME EXPOSED AGAIN TO THE SOUTHWEST OF THE STRONGEST CONVECTION. 
BUT RATHER THAN YOYO-ING THE INTENSITY UP AND DOWN...I HAVE OPTED 
INSTEAD TO MAINTAIN THE PREVIOUS INTENSITY SINCE DOLLY IS PREPARING 
TO GO THROUGH THE DIURNAL CONVECTIVE MAXIMUM PERIOD AND THERE COULD 
BE ANOTHER FLARE UP OF THUNDERSTORMS NEAR THE CENTER. HOWEVER...IF 
CONVECTION DOES NOT RE-DEVELOP...THEN THE INTENSITY WILL CERTAINLY 
BE LOWERED ON THE NEXT ADVISORY.
 
THE INITIAL MOTION ESTIMATE IS 360/10. THERE HAS BEEN A MAJOR 
WESTWARD SHIFT IN THE NHC MODEL GUIDANCE...ESPECIALLY AMONG THE 
AVN...GFDL...NOGAPS AND GFDN MODELS. ONLY THE UKMET HAS REMAINED 
CONSISTENT OVER THE LAST COUPLE OF MODEL RUNS. THERE IS ALSO 
CONSIDERABLE DIVERGENCE IN THE NHC MODEL SUITE AFTER 48 HOURS...WITH 
THE AVN BEING THE FASTEST AND FARTHEST LEFT OF ALL THE MODELS. IT 
TAKES DOLLY TO SOUTHEAST NEWFOUNDLAND IN 72 HOURS AND IS JUST A 
LITTLE WEST OF THE GFDN AND GFDL POSITIONS FOR THE SAME TIME.  THE 
OFFICIAL TRACK WAS SHIFTED WEST OF AND FASTER THAN THE PREVIOUS 
FORECAST...BUT NOT NEARLY AS FAR WEST OR AS FAST AS THE AVN MODEL. 
THE AVN 10-MEMBER ENSEMBLE MEAN FORECAST IS MUCH SLOWER AND FARTHER 
EAST THAN THE AVN...AND THIS SCENARIO WAS FOLLOWED SINCE IT IS 
SIMILAR TO THE NOGAPS AND UKMET SOLUTIONS.

THERE WILL LIKELY BE DIURNAL FLUCTUATIONS IN THE INTENSITY FOR THE 
NEXT 36 TO 48 HOURS. HOWEVER...NO SIGNIFICANT STRENGTHENING IS 
FORECAST SINCE DOLLY IS EXPECTED TO REMAIN UNDER 20 TO 25 KT 
SOUTHWESTERLY TO SOUTHERLY SHEAR. AFTER 48 HOURS AND ESPECIALLY BY 
72 HOURS...DOLLY IS FORECAST TO MOVE UNDER AN AMPLIFYING RIDGE TO 
THE EAST OF A DIGGING AND NEGATIVELY-TILTED UPPER-LEVEL TROUGH. THIS 
SHOULD ALLOW THE SHEAR TO WEAKEN SOME AND MAY PERMIT DOLLY TO 
STRENGTHEN A LITTLE SINCE THE CYCLONE WILL STILL BE OVER 26C SSTS. 
HOWEVER...THE OFFICIAL INTENSITY FORECAST IS NOT NEARLY AS ROBUST AS 
THE SHIPS AND GFDL MODELS WHICH BRING DOLLY TO 76 KT AND 104 KT... 
RESPECTIVELY...BY 72 HOURS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     04/0300Z 23.6N  52.4W    45 KTS
12HR VT     04/1200Z 25.1N  52.3W    40 KTS
24HR VT     05/0000Z 27.6N  52.1W    40 KTS
36HR VT     05/1200Z 30.1N  51.8W    40 KTS
48HR VT     06/0000Z 33.0N  51.0W    45 KTS
72HR VT     07/0000Z 39.0N  48.5W    50 KTS
 
 
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