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Hurricane DEAN


ZCZC MIATCDAT4 ALL
TTAA00 KNHC DDHHMM
HURRICANE DEAN DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT FRI AUG 17 2007
 
THE CONVECTIVE ORGANIZATION OF DEAN IS NOT VERY IMPRESSIVE IN EITHER
SATELLITE IMAGERY OR IMAGERY FROM THE FRENCH RADAR ON MARTINIQUE. 
THERE ARE ONLY OCCASIONAL GLIMPSES OF A RAGGED EYE ON RADAR...AND
THE EYEWALL HAS BEEN AT BEST ABOUT 50 PERCENT COVERAGE.  SATELLITE
INTENSITY ESTIMATES ARE 77 KT FROM BOTH TAFB AND SAB...WHICH ARE
UNCHANGED FROM EARLIER.  THE INITIAL INTENSITY WILL REMAIN 85 KT
FOR THIS ADVISORY...BUT IT IS POSSIBLE THIS IS A LITTLE GENEROUS.

THE INITIAL MOTION IS 275/21.  DEAN IS ON THE SOUTH SIDE OF A
DEEP-LAYER RIDGE...AND THIS SHOULD CONTINUE FOR THE NEXT 72 HR WITH
DEAN REMAINING ON A GENERAL WESTWARD TO WEST-NORTHWESTWARD TRACK. 
THE LARGE-SCALE MODELS HAVE SEEMINGLY RESPONDED TO THE G-IV JET
MISSION BY SHOWING A SLIGHTLY WEAKER RIDGE NORTH OF DEAN...WITH A
MOTION THAT IS SLOWER AND A LITTLE TO THE RIGHT OF PREVIOUS
FORECASTS.  GIVEN THE INITIAL MOTION...THE FIRST 12 HR OF THE
FORECAST TRACK WILL BE ESSENTIALLY UNCHANGED FROM THE PREVIOUS
PACKAGE...WITH A SLIGHT NUDGE TO THE RIGHT FROM 12-72 HR.  AFTER 72
HR...THE FORECAST IS BECOMING MORE PROBLEMATIC DUE TO UNCERTAINTIES
IN THE EVENTUAL INTERACTION OF DEAN AND THE UPPER-LEVEL LOW
FORECAST TO BE OVER THE GULF OF MEXICO.  THE GFDL AND UKMET MODELS
NOW CALL FOR DEAN TO TURN NORTHWESTWARD INTO THE CENTRAL
GULF...WHILE THE CANADIAN...NOGAPS...AND EUROPEAN MODELS CONTINUE
TO FORECAST A WESTWARD MOTION ACROSS THE YUCATAN PENINSULA INTO THE
BAY OF CAMPECHE.  THE GFS AND THE VARIOUS CONSENSUS MODELS ARE
BETWEEN THESE TWO EXTREMES.  THE FORECAST TRACK AFTER 72 HR IS ALSO
NUDGED A LITTLE TO THE RIGHT IN AGREEMENT WITH THE CONSENSUS
GUIDANCE.
 
THE DEVELOPMENT OF DEAN HAS APPARENTLY BEEN SLOWED BY A COMBINATION
OF DRY AIR INTRUSION IN THE WESTERN SEMICIRCLE AND LIGHT WESTERLY
SHEAR.  THESE CONDITIONS MAY PERSIST FOR ANOTHER 12-24 HR...SO THE
INTENSITY FORECAST CALLS FOR SLOW STRENGTHENING DURING THIS TIME. 
AFTER 24 HR...CONDITIONS SHOULD BE FAVORABLE FOR SIGNIFICANT
STRENGTHENING...WITH MOST OF THE INTENSITY GUIDANCE CALLING FOR
DEAN TO REACH AT LEAST CATEGORY 4 STRENGTH.  THE INTENSITY FORECAST
IS THE SAME AS IN THE EARLIER ADVISORY THROUGH 72 HR...THEN
SLIGHTLY STRONGER THEREAFTER.  IT SHOULD BE NOTED THAT THE
WEAKENING FROM 96 TO 120 HR IS BASED ON DEAN CROSSING THE YUCATAN
PENINSULA...AND IF IT INSTEAD MOVES THROUGH THE YUCATAN CHANNEL IT
COULD REMAIN STRONGER.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0900Z 14.3N  60.9W    85 KT
 12HR VT     17/1800Z 14.7N  63.6W    90 KT
 24HR VT     18/0600Z 15.3N  67.0W    95 KT
 36HR VT     18/1800Z 16.1N  70.5W   105 KT
 48HR VT     19/0600Z 16.9N  74.0W   115 KT
 72HR VT     20/0600Z 18.5N  81.0W   120 KT
 96HR VT     21/0600Z 20.5N  87.0W   125 KT
120HR VT     22/0600Z 23.0N  92.0W    95 KT
 
$$
FORECASTER BEVEN
 
NNNN


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Page last modified: Friday, 02-Nov-2007 21:20:43 UTC