Tropical Storm DEAN

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TROPICAL STORM DEAN DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT WED AUG 15 2007

SATELLITE IMAGES INDICATE THAT DEAN HAS A SMALL CENTRAL DENSE
OVERCAST CLOUD PATTERN.  HINTS OF A BANDING EYE HAVE BEEN SEEN ON
VISIBLE AND MICROWAVE IMAGERY...AND SATELLITE INTENSITY ESTIMATES
HAVE BEEN INCREASING.  THE CURRENT INTENSITY ESTIMATE OF 50 KT IS A
BLEND OF TAFB/SAB SUBJECTIVE DVORAK ESTIMATES OF 45 KT AND AMSU/AODT
ESTIMATES OF NEAR 55 KT.

THE INITIAL MOTION IS ABOUT THE SAME AS BEFORE...275/17. A STRONG
DEEP-LAYERED RIDGE LIES TO THE NORTH OF DEAN AND IS FORECAST TO
REMAIN WELL-ESTABLISHED FOR THE NEXT FEW DAYS. NUMERICAL TRACK
FORECAST MODELS HAVE COME INTO BETTER AGREEMENT THAT THE STORM WILL
MAINTAIN THE SAME GENERAL MOTION FOR THE NEXT COUPLE OF DAYS.
BEYOND THREE DAYS...THE FATE OF THE STORM WILL BE PARTIALLY
CONTROLLED BY A MIDDLE-LEVEL TROUGH CURRENTLY OVER THE BAHAMAS.
THIS TROUGH IS FORECAST TO CUT OFF INTO A LOW AND HEAD WESTWARD
UNDER A BUILDING SOUTHEAST UNITED STATES HIGH. MOST OF THE GUIDANCE
SHOWS THE LOW REMAINING FARTHER AWAY FROM DEAN WITH STRONGER
RIDGING CONTINUING ACROSS THE SOUTHWESTERN ATLANTIC OCEAN THAN IN
PREVIOUS MODEL RUNS. THIS SOLUTION WOULD FAVOR A MORE WESTWARD
TRACK IN THE LONG-RANGE..AND THE OFFICIAL FORECAST IS SHIFTED IN
THAT DIRECTION NEAR THE END OF THE FORECAST.

STEADY INTENSIFICATION OF THIS SYSTEM SEEMS TO BE THE BEST BET AS
VERTICAL WIND SHEAR IS FORECAST TO BE LIGHT BY ALL MODELS AND SEA
SURFACE TEMPERATURES UNDER THE STORM START TO RISE.  THE ONLY
NEGATING FACTOR TO INTENSIFICATION MIGHT BE THE ATMOSPHERIC
STABILITY AS SUGGESTED BY THE SHIPS MODEL.  HOWEVER...INTENSITY
GUIDANCE INDICATES THAT DEAN WILL BE A HURRICANE BEFORE IT
ENTERS THE EASTERN CARIBBEAN. THE GFDL/HWRF/SHIPS MODELS ALL
FORECAST DEAN TO BE A MAJOR HURRICANE BY DAY 5...AND SO DOES THE
OFFICIAL FORECAST.  

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/1500Z 12.4N  46.0W    50 KT
 12HR VT     16/0000Z 12.7N  48.6W    55 KT
 24HR VT     16/1200Z 13.1N  52.2W    60 KT
 36HR VT     17/0000Z 13.7N  55.8W    65 KT
 48HR VT     17/1200Z 14.2N  59.2W    75 KT
 72HR VT     18/1200Z 15.5N  66.0W    85 KT
 96HR VT     19/1200Z 16.5N  72.0W    95 KT
120HR VT     20/1200Z 18.0N  78.0W   105 KT
 
$$
FORECASTER BLAKE
 
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