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TROPICAL STORM DOLLY DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
11 PM EDT FRI AUG 30 2002

DESPITE A LACK OF OBVIOUS SHEAR AND A WELL-DEFINED OUTFLOW 
PATTERN...CONVECTION ASSOCIATED WITH DOLLY COLLAPSED FOR A TIME LATE 
THIS AFTERNOON.  THE PRIME SUSPECT AT THE MOMENT IS DRY AIR WRAPPING
AROUND THE WEST SIDE OF THE STORM.  AN SSM/I OVERPASS AT 2055Z 
SHOWED A COMPLETELY EXPOSED CENTER...AND A LATER OVERPASS AT 2339Z 
SHOWED THE CENTER TO THE EAST OR NORTHEAST OF THE NEW BURST OF
CONVECTION THAT HAS RECENTLY DEVELOPED.  SATELLITE INTENSITY
ESTIMATES ARE 45 KT FROM TAFB AND AFWA...AND 35 KT FROM SAB.  THE
MAXIMUM WINDS ARE DECREASED TO 45 KT FOR THIS PACKAGE.

THE SSM/I DATA INDICATES THE CENTER WAS FARTHER NORTH AND EAST
THAN PREVIOUSLY THOUGHT.  THEREFORE...THE INITIAL MOTION IS ADJUSTED
TO A SOMEWHAT UNCERTAIN 290/15.  DOLLY REMAINS SOUTH OF A LOW/MID-
LEVEL RIDGE...BUT IS HEADED FOR A PORTION OF THE RIDGE THAT LARGE-
SCALE MODELS FORECAST TO WEAKEN STARTING IN 36-48 HR.  GUIDANCE
MODELS RESPOND TO THIS PATTERN WITH A SPREAD.  THE AVN...WHICH
SHOWS A POORLY DEVELOPED SYSTEM...CALLS FOR A WEST-NORTHWESTWARD
MOTION WHILE THE UKMET...WHICH MAINTAINS OR DEVELOPS DOLLY...TURNS
THE STORM ALMOST DUE NORTHWARD AFTER 48 HR.  THE BAMD IS TO THE
RIGHT OF EVEN THE UKMET...WHILE THE OTHER MODELS ARE SPREAD BETWEEN
THE AVN AND UKMET.  THE OFFICIAL FORECAST CALLS FOR A WEST-
NORTHWESTWARD MOTION IN PARTIAL CONTINUITY WITH THE PREVIOUS
FORECAST AND ON THE PREMISE THAT DOLLY WILL NOT GET AS DEEP AND
STRONG AS INDICATED IN THE UKMET.  HOWEVER...THE FORECAST TRACK
MAY HAVE TO BE SHIFTED MORE TO THE RIGHT IN LATER PACKAGES IF DOLLY
STRENGTHENS MORE THAN CURRENTLY FORECAST...OR IF THE GUIDANCE
CONTINUES TO CALL FOR AS MUCH OF A WEAKNESS IN THE RIDGE AS
CURRENTLY FORECAST.
 
THE INTENSITY FORECAST IS EVEN MORE PROBLEMATIC.  THE UPPER-LEVEL
OUTFLOW CENTER THAT WAS OVER THE STORM EARLIER HAS MOVED TO THE
SOUTHWEST OF THE CENTER.  THIS SUGGESTS THAT THE ENVIRONMENT IS
LESS FAVORABLE THAN IT WAS EARLIER.  HOWEVER...CONVECTION IS 
TRYING TO MAKE A COMEBACK...AND AS LONG AS THERE IS CONVECTION
NEAR THE CENTER IN A LIGHT-SHEAR ENVIRONMENT THERE IS A CHANCE
DOLLY CAN STRENGTHEN.  THE INTENSITY FORECAST IS BASED ON THE
PREMISE THAT THE CURRENT ARRESTED DEVELOPMENT IS TEMPORARY...AND
THAT THE STORM WILL BEGIN TO INTENSIFY AGAIN AFTER 12 HR.  THIS
INTENSIFICATION WOULD LAST UNTIL ABOUT 48 HR WHEN DOLLY WOULD MOVE
INTO SIGNIFICANT WESTERLY SHEAR.  AN ALTERNATIVE FORECAST SCENARIO
IS THAT DOLLY DOES NOT RECOVER FROM THE CONVECTIVE COLLAPSE AND
WEAKENS FROM THIS POINT ON.
 
FORECASTER BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     31/0300Z 11.8N  39.8W    45 KTS
12HR VT     31/1200Z 12.6N  42.0W    45 KTS
24HR VT     01/0000Z 13.6N  44.7W    50 KTS
36HR VT     01/1200Z 14.6N  47.0W    55 KTS
48HR VT     02/0000Z 15.6N  49.2W    60 KTS
72HR VT     03/0000Z 17.0N  52.0W    60 KTS
 
 
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