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| #147132 (Received by flhurricane at: 4:37 PM 20.Aug.2007) TCDAT4 HURRICANE DEAN DISCUSSION NUMBER 31 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042007 500 PM EDT MON AUG 20 2007 COMMUNICATIONS PROBLEMS ARE PREVENTING THE RECEIPT OF MOST DATA FROM THE AIR FORCE RECONNAISSANCE AIRCRAFT THIS AFTERNOON...ALTHOUGH A 1930Z VORTEX FIX WAS RECEIVED. AT THAT TIME THE MINIMUM PRESSURE WAS 918 MB...WITH MAXIMUM FLIGHT-LEVEL WINDS OF 151 KT. EARLIER IN THE FLIGHT...A PEAK SFMR WIND OF 123 KT WAS OBSERVED. DVORAK CLASSIFICATIONS FROM TAFB AND SAB WERE 127 KT AT 18Z. BASED ON THESE DATA...THE INITIAL INTENSITY IS HELD AT 130 KT. ALL OBJECTIVE GUIDANCE SHOWS ADDITIONAL INTENSIFICATION OVER THE DEEP WARM WATERS OF THE WESTERN CARIBBEAN...AND DEAN COULD REACH CATEGORY FIVE STATUS BEFORE MAKING LANDFALL. A 15Z MICROWAVE PASS SHOWS A PARTIAL OUTER EYEWALL...BUT THIS WILL PROBABLY NOT HAVE ENOUGH TIME TO INDUCE ANY WEAKENING BEFORE LANDFALL. DEAN IS EXPECTED TO MAINTAIN HURRICANE STRENGTH AS IT TRAVERSES THE YUCATAN PENINSULA...AND APPROACH MAJOR HURRICANE STRENGTH AGAIN BEFORE ITS FINAL LANDFALL. THE INITIAL MOTION IS 275/17. DEAN IN EXPECTED TO MAINTAIN A TRACK BETWEEN WEST AND WEST-NORTHWEST TO THE SOUTH OF THE WESTWARD- BUILDING SUBTROPICAL RIDGE. MOST OF THE DYNAMICAL MODEL GUIDANCE HAS TRENDED SOUTH AND THE OFFICIAL FORECAST HAS BEEN NUDGED SOUTHWARD. ALL THE LARGE-SCALE MODELS TAKE THE MID-LEVEL VORTICITY OF DEAN WEST-SOUTHWESTWARD ACROSS THE MOUNTAINS OF CENTRAL MEXICO...AND THE OFFICIAL FORECAST NOW SHOWS A LEFTWARD BEND OF THE TRACK AFTER FINAL LANDFALL. I DO NOT ACTUALLY EXPECT A WELL- DEFINED SURFACE CIRCULATION TO EXIST AT 72 HOURS...BUT A POINT IS PROVIDED SO THAT IT DOESN'T APPEAR THAT THE TRACK ENDS IN THE GULF OF MEXICO. FORECAST POSITIONS AND MAX WINDS INITIAL 20/2100Z 18.2N 84.2W 130 KT 12HR VT 21/0600Z 18.5N 86.7W 140 KT 24HR VT 21/1800Z 19.3N 90.2W 75 KT...INLAND 36HR VT 22/0600Z 20.2N 93.6W 85 KT 48HR VT 22/1800Z 21.0N 97.0W 95 KT 72HR VT 23/1800Z 21.5N 103.0W 30 KT...INLAND 96HR VT 24/1800Z...DISSIPATED $$ FORECASTER FRANKLIN |
