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| #147206 (Received by flhurricane at: 5:11 AM 21.Aug.2007) TCDAT4 HURRICANE DEAN DISCUSSION NUMBER 33 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042007 500 AM EDT TUE AUG 21 2007 DEAN MADE LANDFALL ON THE EAST COAST OF THE YUCATAN PENINSULA NEAR THE CRUISE SHIP PORT OF COSTA MAYA AROUND 0830 UTC...AND THE EYE IS NOW JUST INLAND. OBSERVATIONS FROM AN AIR FORCE HURRICANE HUNTER PLANE INDICATE THAT THE HURRICANE WAS INTENSIFYING RIGHT UP TO LANDFALL. A PEAK FLIGHT-LEVEL WIND OF 165 KT WAS MEASURED JUST NORTH OF THE EYE. MAXIMUM SURFACE WINDS FROM THE SFMR WERE 124 KT...BUT IT IS HIGHLY LIKELY THAT THE MAXIMUM SURFACE WIND SPEED WAS NOT REPORTED BY THE SFMR INSTRUMENT. A GPS DROPSONDE IN THE NORTHERN EYEWALL MEASURED A WIND SPEED OF 178 KT AVERAGED OVER THE LOWEST 150 METERS OF THE SOUNDING. BASED ON THE DROPSONDE AND THE FLIGHT-LEVEL WINDS...THE INTENSITY IS SET AT 145 KT. A DROPSONDE IN THE EYE MEASURED A CENTRAL PRESSURE OF 906 MB JUST PRIOR TO LANDFALL. SOME HISTORIC NOTES ARE IN ORDER HERE. THE 906 MB CENTRAL PRESSURE IS THE NINTH LOWEST ON RECORD FOR AN ATLANTIC BASIN HURRICANE...AND THE THIRD LOWEST AT LANDFALL BEHIND THE 1935 LABOR DAY HURRICANE IN THE FLORIDA KEYS AND HURRICANE GILBERT OF 1988 IN CANCUN MEXICO. DEAN IS ALSO THE FIRST CATEGORY FIVE HURRICANE TO MAKE LANDFALL IN THE ATLANTIC BASIN SINCE ANDREW OF 1992. DEAN WILL WEAKEN AS IT TRAVERSES THE YUCATAN PENINSULA AND THE AMOUNT OF WEAKENING WILL DEPEND ON HOW LONG THE CENTER REMAINS OVER LAND. OUR CURRENT THINKING IS THAT THE CYCLONE WILL STILL BE A BORDERLINE CAT 1/2 HURRICANE WHEN IT EMERGES OVER THE BAY OF CAMPECHE...BUT THERE IS CONSIDERABLE UNCERTAINTY IN THIS FORECAST. ASSUMING THAT THE INNER CORE IS NOT TOO DISRUPTED BY ITS INTERACTION WITH LAND...DEAN SHOULD REGAIN MAJOR HURRICANE STATUS BEFORE ITS FINAL LANDFALL IN MAINLAND MEXICO. INITIAL MOTION IS ESTIMATED TO BE 285/17. DEEP LAYER HIGH PRESSURE NEAR THE NORTHERN GULF COAST SHOULD STEER THE HURRICANE ON A WEST-NORTHWESTWARD TO WESTWARD HEADING FOR THE NEXT COUPLE OF DAYS. THE OFFICIAL TRACK FORECAST IS SIMILAR TO THE PREVIOUS ONE. THE HURRICANE WARNING IS EXTENDED WESTWARD ALONG THE BAY OF CAMPECHE COASTLINE OF MEXICO. FORECAST POSITIONS AND MAX WINDS INITIAL 21/0900Z 18.7N 87.8W 145 KT 12HR VT 21/1800Z 19.1N 90.4W 85 KT...INLAND 24HR VT 22/0600Z 19.6N 93.9W 95 KT...OVER BAY OF CAMPECHE 36HR VT 22/1800Z 20.1N 96.8W 105 KT...INLAND 48HR VT 23/0600Z 20.5N 100.0W 25 KT...INLAND...DISSIPATING 72HR VT 24/0600Z...DISSIPATED $$ FORECASTER PASCH/BROWN |
