HOME	ACTIVE CYCLONES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

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TROPICAL STORM DENNIS DISCUSSION NUMBER  44
NATIONAL WEATHER SERVICE MIAMI FL
5 PM EDT FRI SEP 03 1999
 
CONVECTION ASSOCIATED WITH DENNIS IS LESS WELL DEFINED THAN
EARLIER...WITH RAGGED BANDS PRIMARILY IN THE NORTHEASTERN
SEMICIRCLE. HOWEVER...AN AIR FORCE RESERVE HURRICANE HUNTER RECENTLY
REPORTED A 985 MB CENTRAL PRESSURE WITH 59 KT FLIGHT LEVEL WINDS
NORTHEAST OF THE CENTER. THUS...THE CURRENT INTENSITY REMAINS AT 50
KT.

OF GREATER CONCERN NOW IS THE MOTION. AFTER A WOBBLE EASTWARD THIS
MORNING...THE LATEST SATELLITE IMAGERY AND RECON FIXES SUGGEST A
NORTHWEST MOTION. IF THIS IS THE START OF THE EXPECTED TURN...IT IS
HAPPENING 12 TO 24 HOURS EARLIER THAN MODEL GUIDANCE HAS FORECAST.
TO GUARD AGAINST THIS BEING YET ANOTHER WOBBLE...THE INITIAL MOTION
IS SET TO 300/2. THERE IS LITTLE CHANGE IN THE SYNOPTIC SITUATION OR
THE FORECAST GUIDANCE FROM THE PREVIOUS PACKAGE...AS THE MODELS
STILL AGREE ON WEAKENING OF THE EASTERN U.S. RIDGE THROUGH THE
FORECAST PERIOD. HOWEVER...THE OFFICIAL FORECAST TRACK IS SHIFTED
NORTH OF THE PREVIOUS TRACK AS THE SYSTEM IS NO LONGER MOVING SOUTH.
IT SHOULD BE NOTED THAT DESPITE THE SHIFT THE FORECAST TRACK IS TO
THE RIGHT OF MOST OF THE GUIDANCE...PARTICULARLY IN THE FIRST 36
HOURS.

THERE IS ALSO LITTLE CHANGE IN THE INTENSITY FORECAST PHILOSOPHY
FROM THIS MORNING. DENNIS IS STILL EMBEDDED IN A UPPER LEVEL
CYCLONIC ENVIRONMENT...WITH STRONG NORTHWESTERLY FLOW JUST SOUTHWEST
OF THE CYCLONE. A SHORTWAVE TROUGH FORECAST TO MOVE INTO THE
CAROLINAS SHOULD BUILD A RIDGE OVER DENNIS...WHICH WOULD BE A MORE
FAVORABLE ENVIRONMENT. THE MAIN LIMITATION IS THE SSTS...WHICH ARE
26C-27C OUTSIDE OF THE GULF STREAM. THE INTENSITY FORECAST CALLS FOR
SLIGHT INTENSIFICATION AS DENNIS PASSES OVER THE GULF STREAM...
FOLLOWED BY WEAKENING AFTER LANDFALL.

WITH THE CHANGES IN THE FORECAST TRACK...TROPICAL STORM WATCHES ARE
BEING ISSUED ON EITHER SIDE OF THE TROPICAL STORM WARNING AREA.

BEVEN
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     03/2100Z 33.1N  73.9W    50 KTS
12HR VT     04/0600Z 33.2N  74.2W    50 KTS
24HR VT     04/1800Z 33.6N  75.1W    50 KTS
36HR VT     05/0600Z 34.1N  75.8W    55 KTS
48HR VT     05/1800Z 35.0N  76.5W    55 KTS...INLAND
72HR VT     06/1800Z 38.0N  78.0W    35 KTS...INLAND
 
 
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