Hurricane DEAN

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HURRICANE DEAN DISCUSSION NUMBER  28
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT SUN AUG 19 2007
 
THE EYE OF DEAN HAS BEEN PASSING JUST SOUTH OF JAMAICA SINCE ABOUT
1900 UTC AND HAS JUST CROSSED THE LONGITUDE OF NEGRIL ON THE
WESTERN END OF THE ISLAND.  THE CENTER CAME WITHIN ABOUT 20 N MI OF
PORTLAND POINT ON THE SOUTH-CENTRAL COAST...CLOSE ENOUGH TO BRING
HURRICANE-FORCE WINDS TO KINGSTON.  WHILE PASSING BY JAMAICA...
SATELLITE IMAGERY SUGGESTED THE EYE DIAMETER WAS GRADUALLY
SHRINKING.  AN AIR FORCE HURRICANE HUNTER AIRCRAFT ARRIVED IN THE
EYE OF DEAN AT 0130 UTC AND REVEALED THAT THE PRESSURE HAD FALLEN
TO NEAR 925 MB...AND THAT DEAN NOW HAS A SINGLE EYEWALL AT A
DIAMETER OF ABOUT 15 N MI.  MAXIMUM SURFACE WINDS FROM THE SFMR
HAVE BEEN 121 KT...AND FLIGHT-LEVEL WINDS HAVE BEEN AS HIGH AS 143
KT...BOTH OF WHICH SUPPORT MAINTAINING THE ADVISORY INTENSITY AT
125 KT.
 
DEAN IS HEADING TOWARD 280 DEGREES AT ABOUT 17 KT WITH STEERING
PROVIDED BY A STRENGTHENING MID-LEVEL RIDGE OVER THE SOUTHEASTERN
UNITED STATES.  THE MODELS ALL AGREE THAT THE RIDGE WILL GET EVEN
STRONGER AND MOVE A LITTLE WESTWARD WITH DEAN...MEANING THAT DEAN
WILL PROBABLY MOVE IN A RATHER STRAIGHT LINE UNTIL FINAL LANDFALL
IN MEXICO.  OVERALL THE MODELS HAVE AGAIN EDGED A LITTLE
SOUTHWARD...AND SO HAS THE OFFICIAL FORECAST.  THE NOAA
GULFSTREAM-IV JET CONDUCTED A SYNOPTIC SURVEILLANCE MISSION THIS
EVENING TO PROVIDE DATA FOR THE 0000 UTC MODEL CYCLE.  THE JET WILL
CONTINUE TO FLY MISSIONS EVERY 12 HOURS TO COLLECT DATA THROUGH THE
12Z MODEL CYCLE TUESDAY MORNING.
 
ALL OF THE OBJECTIVE GUIDANCE CALLS FOR STRENGTHENING IN THE
NORTHWESTERN CARIBBEAN WHERE THE SHEAR WILL REMAIN WEAK AND THE
OCEAN HEAT CONTENT VERY HIGH.  THE OFFICIAL FORECAST FOLLOWS SUIT
AND INDICATES THAT DEAN COULD REACH CATEGORY FIVE STATUS DURING THE
NEXT DAY OR SO.  THE HURRICANE WILL WEAKEN WHILE OVER YUCATAN IN
PROPORTION TO JUST HOW LONG IT SPENDS OVER LAND.  THE OPPORTUNITY
FOR RESTRENGTHENING OVER THE SOUTHWESTERN GULF LIKEWISE DEPENDS ON
THE EXACT TRACK...AND THAT WINDOW HAS BEEN SHORTENING WITH THE
SOUTHWARD SHIFTS IN TRACK.  ALTHOUGH NOT EXPLICITLY INDICATED IN
THE NEW OFFICIAL FORECAST...IT IS STILL POSSIBLE THAT DEAN COULD
RESTRENGTHEN AND AGAIN REACH MAJOR HURRICANE STATUS PRIOR TO FINAL
LANDFALL ALONG THE COAST OF MAINLAND MEXICO.

 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/0300Z 17.6N  78.8W   125 KT
 12HR VT     20/1200Z 18.0N  81.4W   130 KT
 24HR VT     21/0000Z 18.5N  84.9W   140 KT
 36HR VT     21/1200Z 19.2N  88.4W   105 KT...INLAND
 48HR VT     22/0000Z 19.8N  91.9W    80 KT
 72HR VT     23/0000Z 21.0N  99.0W    55 KT...INLAND
 96HR VT     24/0000Z...DISSIPATED
 
$$
FORECASTER KNABB
 
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