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| #213921 (Received by flhurricane at: 4:47 PM 05.Sep.2008) TCDAT3 TROPICAL STORM HANNA DISCUSSION NUMBER 36 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL082008 500 PM EDT FRI SEP 05 2008 REPORTS FROM AN AIR FORCE RESERVE HURRICANE HURRICANE HUNTER AIRCRAFT INDICATE THAT HANNA IS JUST BELOW HURRICANE STRENGTH. THE STEPPED FREQUENCY MICROWAVE REPORTED TWO AREAS OF WIND OF ABOUT 65 KT. HOWEVER...DROPSONDE DATA SUGGESTS THAT THE SFMR ESTIMATES WERE A LITTLE TOO HIGH. THE MAXIMUM 850 MB FLIGHT-LEVEL WINDS WERE 75 KT ABOUT 75 N MI EAST OF THE CENTER. THE LAST REPORTED CENTRAL PRESSURE WAS 984 MB...UP A LITTLE FROM THIS MORNING. BASED ON ALL THIS...THE INITIAL INTENSITY IS SET AT 60 KT. IT SHOULD BE NOTED THAT THERE IS NOT MUCH DIFFERENCE METEOROLOGICALLY BETWEEN A 60-KT TROPICAL STORM AND A 65-KT HURRICANE. THE MOTION IS A SOMEWHAT WOBBLY 360/17...WITH A RE-ANALYSIS OF AIRCRAFT DATA SUGGESTING THIS MOTION BEGAN JUST AFTER THE 11Z AIRCRAFT FIX. HANNA IS MOVING AROUND THE WESTERN END OF THE SUBTROPICAL RIDGE OVER THE WESTERN ATLANTIC AND SHOULD ENTER THE WESTERLIES IN 24-36 HR. THIS SHOULD RESULT IN RECURVATURE TO THE NORTHEAST AND ACCELERATION. ALL GUIDANCE AGREES WITH THIS SCENARIO...AND THERE ARE NO SIGNIFICANT OUTLIERS AMONGST THE DYNAMICAL MODELS. THE NEW FORECAST TRACK IS ADJUSTED A LITTLE TO THE RIGHT OF THE PREVIOUS TRACK AND LIES DOWN THE MIDDLE OF THE GUIDANCE ENVELOPE. VERTICAL WIND SHEAR AND DRY AIR ENTRAINMENT ARE STILL ISSUES FOR HANNA...AND SIGNIFICANT STRENGTHENING APPEARS UNLIKELY BEFORE LANDFALL. HOWEVER...THERE IS A POSSIBILITY THAT A CONVECTIVE BURST COULD CAUSE THE STORM TO REACH HURRICANE STRENGTH. THE CYCLONE SHOULD WEAKEN AFTER LANDFALL AND BECOME EXTRATROPICAL IN ABOUT 36 HR. THE GFS AND UKMET CONTINUE TO SUGGEST THE POSSIBILITY OF DEEPENING AS AN EXTRATROPICAL SYSTEM LATE IN THE FORECAST PERIOD...AND THIS IS REFLECTED IN THE 96 AND 120 HR FORECASTS. FORECAST POSITIONS AND MAX WINDS INITIAL 05/2100Z 30.8N 78.7W 60 KT 12HR VT 06/0600Z 33.2N 78.5W 60 KT 24HR VT 06/1800Z 36.7N 76.8W 50 KT...INLAND 36HR VT 07/0600Z 40.7N 72.4W 45 KT...EXTRATROPICAL 48HR VT 07/1800Z 44.5N 65.6W 40 KT...INLAND EXTRATROPICAL 72HR VT 08/1800Z 50.0N 47.5W 40 KT...EXTRATROPICAL 96HR VT 09/1800Z 51.0N 30.0W 45 KT...EXTRATROPICAL 120HR VT 10/1800Z 52.5N 14.0W 45 KT...EXTRATROPICAL $$ FORECASTER BEVEN |
