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| #38843 (Received by flhurricane at: 4:46 AM 11.Aug.2005) TCDAT4 TROPICAL STORM IRENE DISCUSSION NUMBER 27 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT THU AUG 11 2005 THE ORGANIZATION OF IRENE APPEARS TO BE GRADUALLY IMPROVING...WITH A LITTLE MORE CONVECTIVE BANDING IN THE NORTHEAST QUADRANT OF THE CYCLONE AND IN INCREASE IN CONVECTION NEAR MY ESTIMATED CENTER POSITION. THE UPPER-LEVEL OUTFLOW PATTERN ALSO APPEARS STRONG. HOWEVER...A GOOD LOW-LEVEL CENTER IS STILL HARD TO FIND...WITH 06Z FIXES FROM THE THREE AGENCIES SPREAD BY ABOUT 90 NMI...AND THE CIRCULATION APPEARS TO BE ELONGATED FROM SOUTHEAST TO NORTHWEST. DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB ARE 35 KT AND THE ADVISORY INTENSITY WILL REMAIN 35 KT. SHEAR IS NOT EXPECTED TO BE AN INHIBITING FACTOR OVER THE NEXT FEW DAYS...AND THE OFFICIAL FORECAST FOLLOWS THE PREVIOUS ADVISORY IN FORECASTING A GRADUAL INTENSIFICATION TO HURRICANE STRENGTH. THIS FORECAST IS CLOSE TO THE SHIPS GUIDANCE. WITH THE UNCERTAINTY IN THE LOCATION OF THE CENTER...THE INITIAL MOTION IS ALSO UNCERTAIN...BUT IT APPEARS TO BE NEAR 295/12. 00Z RAOB DATA AND GLOBAL ANALYSES SHOW A 500 MB SHORT-WAVE TROUGH IS MOVING EASTWARD JUST OFF THE CAROLINAS...WITH THE SUBTROPICAL RIDGE CENTER JUST EAST OF BERMUDA. AS THE SHORT WAVE LIFTS OUT...HEIGHTS WILL BUILD NEAR AND JUST EAST OF THE U.S. MID-ATLANTIC STATES...AND IRENE'S TRACK COULD TAKE A MORE WESTWARD BEND IN A COUPLE OF DAYS. HOWEVER...MOST OF THE GLOBAL MODEL GUIDANCE SHOWS MID-LEVEL SOUTHWESTERLY FLOW RETURNING OVER THE SOUTHEASTERN STATES BY DAYS 4 AND 5...AND THIS FLOW COULD TURN IRENE NORTHWARD BEFORE IT REACHES THE COAST. THIS IS THE SOLUTION FAVORED BY THE UKMET...GFDL...AND NOGAPS MODELS. EVEN THE BAM MODELS...WHICH EARLIER HAD BEEN WELL TO THE LEFT OF THE GLOBAL MODELS...NOW FAVOR A RECURVING TRACK OFFSHORE. THE GFS...ALTHOUGH IT ESSENTIALLY DISSIPATES IRENE...KEEPS ITS REMNANTS UNDERNEATH THE RIDGE...AND THE GFDN ALSO TAKES THE CYCLONE INLAND. THERE IS SUBSTANTIAL UNCERTAINTY IN THE 4 AND 5 DAY POINTS AND IT IS STILL TOO SOON TO TELL WHAT KIND OF THREAT IRENE COULD POSE FOR THE UNITED STATES. THE OFFICIAL FORECAST HAS BEEN ADJUSTED JUST A BIT TO THE RIGHT OF THE PREVIOUS TRACK...BUT IS STILL WELL TO THE LEFT OF MOST OF THE MODEL GUIDANCE. FORECASTER FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 11/0900Z 24.2N 61.0W 35 KT 12HR VT 11/1800Z 24.9N 62.8W 40 KT 24HR VT 12/0600Z 26.0N 64.9W 45 KT 36HR VT 12/1800Z 27.0N 66.7W 50 KT 48HR VT 13/0600Z 27.9N 68.3W 55 KT 72HR VT 14/0600Z 29.5N 71.0W 60 KT 96HR VT 15/0600Z 31.5N 73.0W 65 KT 120HR VT 16/0600Z 34.0N 75.0W 70 KT |
