000 WTNT45 KNHC 270246 TCDAT5 TROPICAL STORM DANNY DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL052009 1100 PM EDT WED AUG 26 2009 AFTER THE AIR FORCE HURRICANE HUNTER AIRCRAFT LEFT DANNY EARLIER THIS AFTERNOON...VISIBLE SATELLITE IMAGERY SEEMED TO SUGGEST THAT A NEW LOW-LEVEL CENTER WAS FORMING FARTHER TO THE NORTHEAST CLOSER TO THE DEEP CONVECTION. THE OVERALL CIRCULATION REMAINS DISTORTED AND LIKELY CONSISTS OF A BROAD CENTER WITH A SHARP SURFACE TROUGH EXTENDING TO THE SOUTHWEST. NONETHELESS...A NOAA HURRICANE HUNTER AIRCRAFT CONDUCTING A RESEARCH MISSION THIS EVENING DID RELAY SOME RELIABLE SFMR DATA WHICH SUGGESTED THAT THE MAXIMUM WINDS ARE NEAR 45 KT WITHIN THE DEEP CONVECTION ABOUT 100 N MI TO THE NORTHEAST OF THE CENTER. A DROPSONDE FROM THIS FLIGHT ALSO INDICATED THAT THE MINIMUM PRESSURE HAS FALLEN TO NEAR 1006 MB. THE INITIAL MOTION IS ESTIMATED AT 310/9...BUT THIS IS HIGHLY UNCERTAIN SINCE THE CENTER APPEARS TO BE REFORMING. THE FORECAST TRACK REASONING HAS NOT CHANGED...AND THE MODELS ARE IN GOOD AGREEMENT THROUGH 72 HOURS. DANNY IS EXPECTED TO MOVE NORTHWESTWARD AND THEN TURN NORTHWARD WITHIN 48 HOURS AS IT IS STEERED BETWEEN THE SUBTROPICAL RIDGE AND A EASTWARD-MOVING MID-LEVEL LOW CURRENTLY LOCATED OVER THE NORTHERN GULF COAST. THEREAFTER...DANNY IS EXPECTED TO ACCELERATE NORTH-NORTHEASTWARD... PARALLELING THE MID-ATLANTIC AND NEW ENGLAND COASTS...AS IT BECOMES EMBEDDED IN THE FLOW AHEAD OF A DEEPENING UPPER LEVEL TROUGH OVER THE GREAT LAKES. IT SHOULD STILL BE NOTED THAT ANY DEVIATION TO THE LEFT OF THE FORECAST TRACK THROUGH 72 HOURS WOULD BRING DANNY CLOSER TO THE U.S. EAST COAST. ALL THE INTENSITY GUIDANCE CONTINUES TO STRENGTHEN DANNY...BUT IT IS NOT CLEAR WHY THEY MAKE THE CYCLONE SO STRONG. THE UPPER-LEVEL ENVIRONMENT IS EXPECTED TO BE FAVORABLE FOR STRENGTHENING OVER THE NEXT 36-48 HOURS...BUT THEN THE VERTICAL SHEAR IS FORECAST TO INCREASE TO 40 KT...AND MUCH MORE...ONCE DANNY ACCELERATES TO THE NORTH AND NORTHEAST. THE SHIPS AND LGEM MODELS MYSTERIOUSLY SHOW THE SYSTEM STRENGTHENING TO 70-75 KT ONCE THE SHEAR INCREASES. SINCE THIS DOES NOT SEEM VERY REALISTIC...THE OFFICIAL FORECAST LIMITS THE INTENSITY AT 65 KT. ALTHOUGH THE OFFICIAL FORECAST KEEPS DANNY AS A TROPICAL CYCLONE THROUGH 72 HOURS...THE GLOBAL MODEL FIELDS AND FSU CYCLONE PHASE SPACE DIAGRAMS SUGGEST THAT DANNY COULD BE EXTRATROPICAL BY THE TIME IT IS NEAR THE NEW ENGLAND COAST. FORECAST POSITIONS AND MAX WINDS INITIAL 27/0300Z 26.0N 71.6W 45 KT 12HR VT 27/1200Z 26.8N 72.7W 45 KT 24HR VT 28/0000Z 28.1N 74.0W 50 KT 36HR VT 28/1200Z 30.0N 74.6W 55 KT 48HR VT 29/0000Z 32.8N 74.2W 65 KT 72HR VT 30/0000Z 41.5N 69.5W 65 KT 96HR VT 31/0000Z 49.0N 58.5W 55 KT...EXTRATROPICAL 120HR VT 01/0000Z 53.5N 43.0W 40 KT...EXTRATROPICAL $$ FORECASTER BERG/PASCH