HOME	ACTIVE CYCLONES	FORECASTS	IMAGERY	ABOUT TPC	RECONNAISSANCE

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TROPICAL STORM DENNIS DISCUSSION NUMBER   7
NATIONAL WEATHER SERVICE MIAMI FL
11 AM EDT WED AUG 25 1999
 
RECON INDICATE THAT THE SURFACE PRESSURE DECREASED ONLY TO 1004
MB...NOT MUCH SINCE YESTERDAY. HIGH RESOLUTION VISIBLE SATELLITE
IMAGES INDICATE THAT CENTER OF DENNIS IS BETTER DEFINED TODAY BUT
STILL PARTIALLY EXPOSED AND LOCATED TO THE NORTHWEST OF THE
CONVECTION. DESPITE MODELS FORECASTING A 200 MB ANTICYCLONE OVER THE
SYSTEM...IT HAS NOT MATERIALIZED YET AND SHEAR CONTINUES. 
HOWEVER...THE OVERALL OUTFLOW IS NOW BEGINNING TO BECOME BETTER
ESTABLISHED...AS FORECAST BY GLOBAL MODELS AND CONVECTION CONTINUES
TO INCREASE.  BOTH SHIPS AND GFDL MODELS STRENGTHEN THE TROPICAL
CYCLONE.  THEREFORE...DENNIS IS FORECAST TO BECOME A HURRICANE BY 36
HOURS OR SO.
 
DENNIS IS NEARLY STATIONARY AS INDICATED BY RECON DATA...PERHAPS
BECAUSE IT IS STILL IN A FORMATIVE STAGE BUT IS FORECAST TO RESUME A
SLOW WEST-NORTHWEST TRACK LATER TODAY. THE MAIN PLAYER IS THE LARGE
MID-TO UPPER LEVEL TROUGH WHICH IS FORECAST BY GLOBAL MODELS TO BE
ALONG THE EASTERN UNITED STATES.  THE TIMING OF THE INTERACTION OF
THE TROUGH WITH DENNIS IS CRITICAL BECAUSE IT MAY DETERMINE IF THE
TROPICAL CYCLONE EVENTUALLY MOVES NORTHWARD OR NOT.  IF DENNIS
CONTINUES TO MOVE LITTLE AND MISSES THE TROUGH...THIS WOULD GIVE
TIME FOR THE LARGE SCALE PATTERN TO CHANGE IN THE LONGER TERM.  THE
OFFICIAL FORECAST KEEPS A WEST-NORTHWEST TRACK WITH A GRADUAL TURN
TO THE NORTHWEST AND NORTH-NORTHWEST AHEAD OF THE TROUGH...WHICH IS
THE MOST LIKELY SCENARIO AT THIS TIME.   THIS TRACK IS IN BETWEEN
TWO SOLUTIONS...GFDL WITH BAM... AND NOGAPS WITH UK...MODELS.
 
AVILA
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL     25/1500Z 23.3N  72.5W    40 KTS
12HR VT     26/0000Z 23.5N  73.5W    45 KTS
24HR VT     26/1200Z 24.2N  75.0W    55 KTS
36HR VT     27/0000Z 25.2N  76.0W    65 KTS
48HR VT     27/1200Z 26.5N  77.5W    75 KTS
72HR VT     28/1200Z 30.0N  78.5W    85 KTS
 
 
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