HOME	ARCHIVES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

ZCZC MIATCDEP2 ALL
TTAA00 KNHC DDHHMM
TROPICAL STORM ISELLE DISCUSSION NUMBER   6
NATIONAL WEATHER SERVICE MIAMI FL
2 AM PDT MON SEP 16 2002

ISELLE CONTINUES TO GET BETTER ORGANIZED THIS MORNING WITH COOLING
CONVECTIVE TOPS AND SOMEWHAT INCREASED CONVECTIVE BANDING.  HOW
ORGANIZED IS SOMEWHAT OF A QUESTION...AS A 0408Z SSM/I OVERPASS
HINTED THAT THE LOW-LEVEL CENTER MIGHT BE PARTLY EXPOSED NEAR THE
EASTERN END OF THE BAND RATHER THAN WRAPPED INTO IT.  SUBSEQUENT
IR IMAGERY DOES NOT CONCLUSIVELY SHOW AN EXPOSED CENTER...SO IT
IS BELIEVED THAT THE CENTER IS NOW BETTER INVOLVED WITH THE 
CONVECTION.  SATELLITE INTENSITY ESTIMATES ARE 45 KT FROM TAFB AND
AFWA...AND 30 KT FROM SAB.  THE MAXIMUM WINDS ARE INCREASED TO 45
KT.
 
GIVEN THE UNCERTAINTIES IN THE INITIAL POSITION...WHICH IS EAST
OF ALL THE FIXES...THE INITIAL MOTION IS 295/12.  WATER VAPOR
IMAGERY INDICATES MID-LEVEL RIDGING TO THE NORTH OF ISELLE...AND
LARGE-SCALE MODELS INDICATE THAT THIS SHOULD PERSIST FOR 36-48 HR
BEFORE A WEAKNESS OR BREAK DEVELOPS.  THIS SCENARIO SUGGESTS
ISELLE SHOULD CONTINUE WEST-NORTHWESTWARD FOR 36-48 HR...FOLLOWED
BY SOME MORE NORTHWARD TURN.  TRACK GUIDANCE IS SOMEWHAT SPLIT
ON WHETHER SUCH A TURN WILL OCCUR...WITH EXTREMES RANGING BETWEEN
THE GFDL AND GFDN CURVING ISELLE NORTHWARD AND NORTHEASTWARD AND
THE BAMM AND BAMS BENDING IT WESTWARD.  THE OFFICIAL FORECAST WILL
CALL FOR A NORTHWESTWARD TURN AFTER 48 HR AND IS IN BEST AGREEMENT
WITH THE AVN.
 
SOME EASTERLY SHEAR CONTINUES...AND LARGE-SCALE MODELS SUGGEST
PERHAPS 12 HR OR SO BEFORE IT DIMINISHES.  THE INTENSITY FORECAST
THUS CALLS FOR SLOW STRENGTHENING DURING THAT TIME...WITH FASTER
STRENGTHENING TO A HURRICANE THEREAFTER.  BY 48 HR...ISELLE SHOULD
BE OVER COLD ENOUGH WATER TO CHANGE STRENGTHENING TO WEAKENING.

ALTHOUGH WARNINGS HAVE BEEN DISCONTINUED ALONG THE MEXICAN COAST...
THERE IS STILL THE POSSIBILITY THAT GUSTS TO TROPICAL STORM FORCE
MAY OCCUR IN SQUALLS ALONG THE COAST BETWEEN MANZANILLO AND CABO
CORRIENTES.  THIS IS ESPECIALLY THE CASE IF THE CENTER IS CLOSER
TO LAND THAN CURRENTLY ANALYZED.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     16/0900Z 17.6N 108.6W    45 KTS
12HR VT     16/1800Z 18.4N 110.3W    50 KTS
24HR VT     17/0600Z 19.4N 112.6W    60 KTS
36HR VT     17/1800Z 20.4N 115.0W    65 KTS
48HR VT     18/0600Z 21.3N 116.8W    65 KTS
72HR VT     19/0600Z 23.0N 119.0W    60 KTS
 
 
NNNN