000
WTNT44 KNHC 171457
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT FRI AUG 17 2007
 
THE CENTER OF DEAN CROSSED THE LESSER ANTILLES THIS MORNING BETWEEN
ST. LUCIA AND MARTINIQUE AS INDICATED BY THE MARTINIQUE RADAR.  AT
0842 UTC...THE METEOROLOGICAL SERVICE OF MARTINIQUE REPORTED
SUSTAINED WINDS OF 66 KNOTS WITH GUSTS TO 90 KNOTS. AN AIR FORCE
PLANE REACHED THE HURRICANE AND MEASURED A MINIMUM PRESSURE OF 964
MB...FLIGHT LEVEL WINDS OF 100 KNOTS AND A CLOSED EYEWALL.  THE
CLOUD PATTERN HAS BECOME BETTER ORGANIZED SINCE YESTERDAY WITH
PLENTY OF BANDING FEATURES AND OUTFLOW IN ALL QUADRANTS. LATEST
VISIBLE IMAGE SHOWS AN EYE FEATURE.  BOTH SATELLITE PRESENTATION
AND DATA FROM THE SFMR ON THE PLANE SUPPORT AN INITIAL INTENSITY OF
90 KNOTS. THE OFFICIAL INTENSITY FORECAST CALLS FOR STRENGTHENING
SINCE GUIDANCE SUGGESTS THAT THE SHEAR WILL BE LOW ACROSS THE
CARIBBEAN. DEAN COULD BECOME A VERY DANGEROUS HURRICANE WHEN IT
REACHES THE WESTERN CARIBBEAN WHERE THE OCEAN HEAT CONTENT IS THE
HIGHEST. IN FACT THE OFFICIAL FORECAST IS A CONSENSUS OF
SHIPS...GFDL AND HWRF MODELS.
 
THE MOTION OF DEAN...280/18...CONTINUES TO BE CONTROLLED BY A STRONG
RIDGE TO THE NORTH. A MID- TO UPPER-LEVEL LOW OVER THE WESTERN
BAHAMAS IS EXPECTED TO RUN WESTWARD AHEAD OF THE HURRICANE AND THE
ONLY POSSIBLE INFLUENCE ON THE TRACK OF THE HURRICANE IS TO ADD A
SMALL WEST-NORTHWESTWARD COMPONENT IN THE LATER PERIODS.  THE
OFFICIAL FORECAST FOLLOWS THE MIDDLE OF THE GUIDANCE ENVELOPE WITH A
SLIGHT ADJUSTMENT TO THE NORTH DUE TO THE GFDL AND UKMET MODELS.
THE GFDL SOLUTION INSISTS ON A MORE WEST-NORTHWEST TRACK THROUGH THE
YUCATAN CHANNEL...BRINGING DEAN INTO THE NORTHWEST GULF OF MEXICO
AS A STRONGER HURRICANE THAN INDICATED IN THE OFFICIAL FORECAST. IT
SHOULD BE NOTED THAT GUIDANCE FOR DAY 4 AND 5 IS MORE UNCERTAIN
TODAY THAN YESTERDAY.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/1500Z 14.6N  62.6W    90 KT
 12HR VT     18/0000Z 15.0N  65.5W   100 KT
 24HR VT     18/1200Z 15.8N  69.0W   105 KT
 36HR VT     19/0000Z 16.7N  72.3W   110 KT
 48HR VT     19/1200Z 17.5N  75.5W   120 KT
 72HR VT     20/1200Z 19.5N  82.0W   130 KT
 96HR VT     21/1200Z 21.5N  88.0W   100 KT...INLAND
120HR VT     22/1200Z 24.0N  94.0W   105 KT
 
$$
FORECASTER AVILA