HOME	ARCHIVES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDEP2 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ISELLE DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
8 AM PDT MON SEP 16 2002
 
THE INITIAL POSITION IS VERY DIFFICULT TO DETERMINE ON INFRARED 
IMAGERY...AND IS BASED ESSENTIALLY ON CONTINUITY WITH THE PREVIOUS 
ADVISORY...ALTHOUGH IT MAY BE A LITTLE NORTH OF WHERE WE ARE 
CARRYING IT.  THE SYSTEM IS GENERATING DEEP CONVECTION WITH SOME 
CURVATURE...AND APPEARS TO BE CONSOLIDATING...BUT STILL IS UNDER 
EASTERLY SHEAR.  DVORAK CLASSIFICATIONS ARE A CONSENSUS 3.0...SO THE 
INITIAL INTENSITY REMAINS 45 KT.

THE SUBTROPICAL RIDGE TO THE NORTH OF ISELLE DOES NOT APPEAR TO BE 
PARTICULARLY STRONG AND IS FORECAST BY GLOBAL MODELS TO WEAKEN 
FURTHER. THEREFORE I EXPECT THE FORWARD SPEED TO GRADUALLY SLOW 
DURING THE FORECAST PERIOD.  NEAR THE END OF THE PERIOD...THE RIDGE 
APPEARS TO BREAK DOWN ENTIRELY.  MODEL GUIDANCE IS IN GOOD AGREEMENT 
FOR THE NEXT 48 HOURS ON A WEST-NORTHWESTERLY TRACK.  AFTER 
THAT...THE AMOUNT OF RECURVATURE IS LIKELY TO DEPEND ON HOW MUCH OF 
A SYSTEM IS PRESENT WHEN ISELLE MOVES OVER COOLER WATERS.  THE 
OFFICIAL FORECAST IS NORTH OF AND SLOWER THAN THE PREVIOUS 
ADVISORY...AND IS IN GOOD AGREEMENT WITH THE AVN ENSEMBLE MEAN.

AS ISELLE GAINS LATITUDE IT SHOULD GET OUT FROM UNDER THE EASTERLY 
SHEAR...AND THE WATER SHOULD REMAIN WARM ENOUGH FOR THE NEXT 36 
HOURS OR SO TO ALLOW THE SYSTEM TO STRENGTHEN.  HOWEVER...THE WINDOW 
OF OPPORTUNITY IS NOT LARGE.
 
FORECASTER FRANKLIN/MAINELLI
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     16/1500Z 18.3N 109.5W    45 KTS
12HR VT     17/0000Z 19.2N 111.2W    50 KTS
24HR VT     17/1200Z 20.2N 113.0W    55 KTS
36HR VT     18/0000Z 21.2N 114.7W    65 KTS
48HR VT     18/1200Z 22.2N 116.0W    65 KTS
72HR VT     19/1200Z 24.0N 118.0W    55 KTS
 
 
NNNN