Tropical Storm DENNIS

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TROPICAL STORM DENNIS DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
11 PM EDT TUE JUL 05 2005
 
DENNIS HAS CONTINUED TO GET BETTER ORGANIZED AND HAS INTENSIFIED
DURING THE PAST 6 HOURS. A NOAA RECON REPORT AT 650 MB INDICATED
FLIGHT-LEVEL WINDS OF 45 KT IN THE NORTHEAST QUADRANT AT 05/2114Z
AND A CENTRAL PRESSURE OF 1001 MB. USING ABOUT 95 PERCENT OF THE
FLIGHT-LEVEL WINDS AND A T3.0/45 KT SATELLITE INTENSITY ESTIMATE
FROM TAFB AND SAB SUPPORT INCREASING THE INITIAL INTENSITY TO 45
KT. UPPER-LEVEL OUTFLOW REMAINS IMPRESSIVE IN ALL QUADRANTS.

THE INITIAL MOTION ESTIMATE IS 295/15. DENNIS HAS SLOWED ITS FORWARD
SPEED SOMEWHAT...POSSIBLY DUE TO RE-ORGANIZATION OF THE DEEP
CONVECTION AROUND THE CENTER. THE NHC MODEL GUIDANCE REMAINS
TIGHTLY CLUSTERED ABOUT THE PREVIOUS FORECAST TRACKS AND TAKES
DENNIS BETWEEN HAITI AND JAMAICA AND THEN BETWEEN JAMAICA AND
SOUTHEASTERN CUBA THROUGH 72 HOURS AS THE CYCLONE MOVES AROUND THE
SOUTHWEST PERIPHERY OF A DEEP-LAYERED SUBTROPICAL RIDGE THAT LIES
EAST-WEST ACROSS THE WESTERN ATLANTIC AND FLORIDA. HOWEVER...AFTER
THAT...THE FORECAST BECOMES A LITTLE MURKY. ALL OF THE MODELS
WEAKEN THE WESTERN PORTION OF THE RIDGE OVER FLORIDA AS A SHARP
SHORTWAVE TROUGH OVER THE CENTRAL U.S. DIGS SOUTHEASTWARD INTO THE
CENTRAL GULF OF MEXICO BY DAYS 4 AND 5...BEFORE LIFTING OUT SLOWLY
TO THE NORTHEAST AFTER THAT. SINCE DENNIS IS A LARGER THAN AVERAGE
TROPICAL CYCLONE THAT IS FORECAST TO BECOME A MAJOR HURRICANE IN
DAYS 3-5...THE LARGE OUTER CIRCULATION COULD ERODE THE RIDGE EVEN
MORE...RESULTING IN WEAKER STEERING CURRENTS THAN THE 5-8 KT THAT
THE MODELS ARE FORECASTING. THE OFFICIAL TRACK IS ALMOST IDENTICAL
TO THE PREVIOUS FORECAST AND IS ALONG THE EXTREME EASTERN..OR
RIGHT...SIDE OF THE MODEL GUIDANCE ENVELOPE.
 
DENNIS IS EXPECTED TO REMAIN IN A VERY LOW SHEAR AND HIGH SST
ENVIRONMENT..WHICH UNFORTUNATELY ARE PRIME CONDITIONS FOR PRODUCING
INTENSE HURRICANES. THE OFFICIAL INTENSITY FORECAST IS MUCH HIGHER
THAN THE PREVIOUS FORECASTS...BUT IS LESS THAN THE SHIPS AND GFDL
INTENSITY MODELS...WHICH BRING DENNIS TO 108 KT IN 96 HOURS AND 113
KT IN 60 HOURS...RESPECTIVELY.

FORECASTER STEWART
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      06/0300Z 14.6N  69.2W    45 KT
 12HR VT     06/1200Z 15.8N  71.3W    55 KT
 24HR VT     07/0000Z 17.4N  74.0W    70 KT
 36HR VT     07/1200Z 18.8N  76.5W    80 KT
 48HR VT     08/0000Z 20.1N  78.8W    90 KT
 72HR VT     09/0000Z 22.4N  82.4W   100 KT
 96HR VT     10/0000Z 24.5N  84.5W   100 KT
120HR VT     11/0000Z 27.0N  86.5W   100 KT
 
 
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