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TROPICAL STORM DOLLY DISCUSSION NUMBER  24
NATIONAL WEATHER SERVICE MIAMI FL
5 AM EDT WED SEP 04 2002
 
THE INITIAL INTENSITY IS NOW A VERY GENEROUS 35 KT BASED ON A DVORAK
SATELLITE INTENSITY ESTIMATE OF 35 KT FROM ALL THREE SATELLITE 
AGENCIES. DOLLY HAS A FULLY EXPOSED LOW-LEVEL CIRCULATION LOCATED 
SOUTHWEST OF THE MAIN CONVECTION AND BANDING FETAURES.
 
THE INITIAL MOTION ESTIMATE IS 360/06. THERE IS NO SIGNIFICANT 
CHANGE TO THE PREVIOUS FORECAST TRACK OR REASONING. THE NHC MODEL 
GUIDANCE REMAINS IN GOOD AGREEMENT ON A GENERAL NORTHWARD MOTION 
THROUGH 36 HOURS AND THEN DIVERGES SIGNIFICANTLY AFTER THAT. THE AVN 
REMAINS THE FASTEST AND FARTHEST WEST OF ALL THE MODELS...WHILE THE 
GFDL HAS SLOWED ITS FORWARD SPEED AND HAS SHIFTED ITS TRACK TO THE 
EAST...WHICH IS MORE IN LINE WITH THE UKMET AND NOGAPS MODELS. THE 
MAIN CONCERN IS THE FORWARD SPEED EARLY IN THE PERIOD...AND WHETHER 
DOLLY EVEN EXISTS AFTER 24 HOURS. GIVEN THE TENACITY OF THIS SYSTEM 
IN THE FACE OF SUCH STRONG SHEAR IN THE PAST...I HAVE DECIDED TO 
HOLD ONTO THE CYCLONE THROUGH THE FORECAST PERIOD. IF DOLLY MOVES 
SLOWER THAN THE AVN MODEL IS INDICATING...THEN THE SYSTEM WILL GET 
PICKED UP BY AN APPROACHING MID-LATITUDE TROUGH MUCH LATER AND MOVE 
MORE SLOWLY TO THE NORTHEAST RATHER THAN FASTER TO THE NORTH LIKE 
THE AVN IS FORECASTING. THE OFFICIAL TRACK IS JUST AN UPDATE OF THE 
PREVIOUS FORECAST TRACK...ALBEIT SLOWER THROUGH 24 HOURS...AND IS 
SIMILAR TO THE UKMET-GFDL-NOGAPS CONSENSUS.
 
NO SIGNIFICANT STRENGTHENING IS FORECAST DURING THE NEXT 36 HOURS 
DUE TO STRONG SOUTHWESTERLY TO SOUTHERLY SHEAR. IN FACT...DOLLY MAY 
NOT EVEN SURVIVE THE DAY IF DEEP CONVECTION DOES NOT REDEVELOP NEAR 
THE LOW-LEVEL CENTER WITHIN THE NEXT 12 HOURS. ASSUMING DOLLY DOES 
SURVIVE...BY 48 HOURS UPPER-LEVEL CONDITIONS WILL BECOME LESS 
HOSTILE AS THE CYCLONE MOVES UNDER AN AMPLIFYING RIDGE TO THE EAST 
OF A NEGATIVELY-TILTED UPPER-LEVEL TROUGH THAT IS FORECAST BY ALL 
THE MODELS TO DEVELOP TO THE WEST OF THE CYCLONE. THIS SHOULD HELP 
TO DECREASE THE VERTICAL SHEAR AND ALLOW FOR SOME STRENGTHENING TO 
OCCUR. HOWEVER...THE OFFICIAL INTENSITY FORECAST REMAINS WELL BELOW 
THE THE SHIPS AND GFDL MODELS WHICH BRING DOLLY TO 66 KT AND 94 
KT...RESPECTIVELY...BY 72 HOURS.
 
FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     04/0900Z 23.8N  52.4W    35 KTS
12HR VT     04/1800Z 25.5N  52.3W    35 KTS
24HR VT     05/0600Z 28.1N  52.1W    35 KTS
36HR VT     05/1800Z 31.0N  51.4W    40 KTS
48HR VT     06/0600Z 34.0N  50.4W    45 KTS
72HR VT     07/0600Z 42.0N  47.0W    50 KTS
 
 
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