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| #147029 (Received by flhurricane at: 11:11 PM 19.Aug.2007) TCDAT4 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 |
