000
WTNT44 KNHC 180305
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  20...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT FRI AUG 17 2007

...CORRECTED ERRONEOUS INDICATOR OF INLAND AT 96 HOURS IN TABLE...
 
DEAN HAS BEEN STEADILY INTENSIFYING TONIGHT.  THE U.S. AIR FORCE
RECONNAISSANCE AIRCRAFT RECENTLY MEASURED MAXIMUM FLIGHT-LEVEL
WINDS OF 138 KT...CORRESPONDING TO ABOUT 124 KT AT THE SURFACE.  IN
ADDITION...THE AIRCRAFT IS EQUIPPED WITH THE STEPPED-FREQUENCY
MICROWAVE RADIOMETER WHICH MEASURED WINDS AS STRONG AS 123 KT THIS
EVENING.  NOT SURPRISINGLY...THE CENTRAL PRESSURE HAS BEEN
DROPPING...WITH THE LATEST AIRCRAFT MEASUREMENT BEING 937 MB.  THE
ADVISORY INTENSITY IS SET TO 125 KT...WHICH IS ALSO CONSISTENT WITH
DVORAK INTENSITY ESTIMATES.  THE AIRCRAFT DATA ALSO INDICATE THE
STORM HAS BECOME A GOOD BIT LARGER...AND WIND RADII HAVE BEEN
EXPANDED IN ALL QUADRANTS.  DEAN MIGHT ALSO HAVE A CLOSE ENCOUNTER
WITH NOAA BUOY 42059...LESS THAN 100 N MI DIRECTLY AHEAD OF THE
CENTER OF THE HURRICANE...IN A FEW HOURS.

THE INITIAL MOTION ESTIMATE IS 275/16...JUST A LITTLE SLOWER THAN
BEFORE.  THE OVERALL TRACK FORECAST REASONING HAS NOT CHANGED...AND
THE MODELS ARE IN GOOD AGREEMENT THROUGH 72 HOURS ON A TRACK TOWARD
THE NORTHWESTERN CARIBBEAN.  THEREAFTER...THE MODELS NOTABLY
DISAGREE AND HAVE GENERALLY SHIFTED A BIT TO THE SOUTH...INCLUDING
THE NORTHERN OUTLYING GFDL.  THE OFFICIAL FORECAST...HOWEVER...HAS
NOT CHANGED NOTICEABLY...SINCE THE MODELS MIGHT SHIFT BACK THE
OTHER WAY.  THE SIGNIFICANT SPREAD IN THE MODELS AT DAYS FOUR AND
FIVE IS INDICATIVE OF THE LARGE UNCERTAINTIES TYPICAL OF THOSE
LONGER FORECAST RANGES.  THE NHC WIND SPEED PROBABILITY TEXT AND
GRAPHICAL PRODUCTS INCLUDED IN THIS ADVISORY PACKAGE ALSO REFLECT
THESE UNCERTAINTIES.  THE CHANCES OF TROPICAL STORM FORCE WINDS ARE
SIMILAR AT EACH LOCATION ALONG THE ENTIRE WESTERN AND NORTHERN
COASTS OF THE GULF OF MEXICO...AND IT IS TOO EARLY TO DIFFERENTIATE
THE RISK OF HURRICANE FORCE WINDS BETWEEN ANY OF THESE LOCATIONS.

THE FUTURE INTENSITY OF DEAN...GIVEN THE WEAK SHEAR AND WARM WATERS
AHEAD...WILL LIKELY BE CONTROLLED BY INTERNAL STRUCTURAL CHANGES
AND/OR BRIEF INTERACTIONS WITH LAND.  THE OFFICIAL FORECAST CALLS
FOR AN INTENSITY NEAR THE CATEGORY 4/5 THRESHOLD THROUGH 72
HOURS...AND IS ONLY LOWERED ON DAYS 4 AND 5 DUE TO POTENTIAL
PASSAGE OVER YUCATAN.

 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/0300Z 14.9N  65.9W   125 KT
 12HR VT     18/1200Z 15.5N  68.4W   130 KT
 24HR VT     19/0000Z 16.4N  71.7W   135 KT
 36HR VT     19/1200Z 17.3N  75.0W   135 KT
 48HR VT     20/0000Z 18.2N  78.4W   135 KT
 72HR VT     21/0000Z 20.0N  85.5W   140 KT
 96HR VT     22/0000Z 22.5N  91.5W   110 KT
120HR VT     23/0000Z 25.0N  97.5W   110 KT...NEAR COAST OF MEXICO
 
$$
FORECASTER KNABB