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| #294728 (Received by flhurricane at: 10:43 PM 10.Sep.2009) TCDAT2 HURRICANE FRED DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009 1100 PM AST THU SEP 10 2009 SOUTHWESTERLY SHEAR CONTINUES TO DISRUPT THE STRUCTURE OF FRED. A COMPARISON OF THE 37- AND 85-GHZ CHANNEL IMAGERY FROM A 2212 UTC TRMM PASS INDICATES THAT THE MID-LEVEL CENTER OF ROTATION IS DISPLACED ABOUT 20-25 N MI NORTH OF THE LOW-LEVEL CENTER...AND THE MID-LEVEL REMNANT EYEWALL IS COMPLETELY ERODED ON THE SOUTHERN SIDE. THIS PATTERN HAS YIELDED DVORAK CURRENT INTENSITY ESTIMATES OF 77 KT FROM BOTH TAFB AND SAB...SO THE INITIAL INTENSITY IS DECREASED TO 75 KT FOR THIS ADVISORY. ALL OF THE INTENSITY GUIDANCE GRADUALLY WEAKENS FRED DUE TO 20-30 KT OF SOUTHWESTERLY SHEAR AND MARGINALLY WARM SEA SURFACE TEMPERATURES OVER THE NEXT 48 HOURS... WITH EVEN STRONGER SHEAR AFTER THAT. THERE IS VERY LITTLE SPREAD IN THE INTENSITY MODELS...AND THE NHC FORECAST CALLS FOR FRED TO WEAKEN TO A TROPICAL STORM BY 24 HOURS AND ULTIMATELY A REMNANT LOW BY DAY 4. THE STEERING CURRENTS AROUND FRED ARE BEGINNING TO COLLAPSE AND THE INITIAL MOTION IS ESTIMATED AT 350 DEGREES AT 3 KT. ONLY A SLOW NORTH TO NORTH-NORTHEASTWARD DRIFT IS EXPECTED DURING THE NEXT 48 HOURS AS FRED TEMPORARILY RESPONDS TO A MID-LEVEL TROUGH TO ITS NORTH. ONCE IT WEAKENS AND BECOMES A SHALLOWER SYSTEM...THE CYCLONE IS EXPECTED TO TURN NORTHWESTWARD AND WEST-NORTHWESTWARD WITH AN INCREASE IN FORWARD SPEED UNDER THE INFLUENCE OF THE LOW-LEVEL SUBTROPICAL RIDGE. THE NEW OFFICIAL FORECAST IS SLIGHTLY EAST OF THE PREVIOUS TRACK DURING THE FIRST 48 HOURS BUT DOES NOT SHOW AS MUCH OF AN EASTWARD BEND AS THE TVCN MODEL CONSENSUS. STILL...THE MOTION WILL BE SLOW...AND FRED COULD MEANDER A BIT DURING THE FIRST COUPLE OF DAYS OF THE FORECAST PERIOD BEFORE ACCELERATING NORTHWESTWARD AFTER 72 HOURS. FORECAST POSITIONS AND MAX WINDS INITIAL 11/0300Z 17.4N 35.1W 75 KT 12HR VT 11/1200Z 17.7N 35.0W 65 KT 24HR VT 12/0000Z 17.9N 34.9W 55 KT 36HR VT 12/1200Z 18.0N 34.8W 45 KT 48HR VT 13/0000Z 18.3N 34.7W 35 KT 72HR VT 14/0000Z 20.0N 36.5W 30 KT 96HR VT 15/0000Z 21.5N 41.0W 25 KT...REMNANT LOW 120HR VT 16/0000Z 23.0N 45.5W 20 KT...REMNANT LOW $$ FORECASTER BERG |
