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| #287442 (Received by flhurricane at: 4:43 PM 11.Aug.2009) TCDAT2 TROPICAL DEPRESSION TWO DISCUSSION NUMBER 3 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009 500 PM AST TUE AUG 11 2009 THE DEPRESSION IS HAVING SOME TROUBLE DEVELOPING WELL-DEFINED CONVECTIVE BANDING...AND THE DEEP CONVECTION THAT DOES EXIST IS LIMITED TO THE WESTERN SEMICIRCLE. THERE HAS BEEN NO IMPROVEMENT TO THE CONVECTIVE STRUCTURE SINCE THIS MORNING...AND DVORAK FINAL T-NUMBERS ARE T1.5 FROM BOTH TAFB AND SAB. THIS SUPPORTS KEEPING THE INITIAL INTENSITY AT 25 KT. THIS FORECAST PACKAGE MAKES NO CHANGES TO THE INTENSITY FORECAST. THE DEPRESSION WILL BE TRAVERSING MARGINALLY WARM WATER AND BE UNDER LIGHT SHEAR CONDITIONS DURING THE NEXT 3 TO 4 DAYS...ALTHOUGH THE AMBIENT MID-LEVEL ENVIRONMENT IS EXPECTED TO REMAIN DRY AND STABLE. SLOW STRENGTHENING IS STILL INDICATED IN THE OFFICIAL FORECAST...PEAKING NEAR 50 KT IN ABOUT 4 DAYS. THEREAFTER...THE DEPRESSION IS EXPECTED TO REACH LATITUDES WHERE IT WILL BECOME IMPACTED BY STRONGER UPPER-LEVEL WESTERLY WINDS...AND SOME WEAKENING IS SHOWN AT THE END OF THE FORECAST PERIOD. THE CENTER OF THE DEPRESSION IS A LITTLE DIFFICULT TO LOCATE...BUT IT APPEARS TO BE MOVING AT AN AVERAGE MOTION OF 275/10 AS IT IS STEERED BY THE LOW- TO MID-LEVEL FLOW SOUTH OF THE SUBTROPICAL RIDGE. INTERESTINGLY...THE GFS...UKMET...AND CANADIAN MODELS ALL SHOW A WEST-SOUTHWESTWARD MOTION OCCURRING FOR THE NEXT 48 HOURS OR SO...SO THE OFFICIAL FORECAST INDICATES THAT THE DEPRESSION WILL MOVE DUE WEST OVER THE NEXT 24 HOURS. THEREAFTER...THE MODELS ALL INDICATE A WEST-NORTHWESTWARD TURN AS A WEAKNESS DEVELOPS IN THE RIDGE...BUT THE BULK OF THEM LIE SOUTH OF THE PREVIOUS FORECAST. THE NEW FORECAST IS THEREFORE SHIFTED JUST A LITTLE TO THE WEST ON DAYS 4 AND 5. FORECAST POSITIONS AND MAX WINDS INITIAL 11/2100Z 14.6N 30.4W 25 KT 12HR VT 12/0600Z 14.7N 32.0W 30 KT 24HR VT 12/1800Z 14.7N 34.3W 35 KT 36HR VT 13/0600Z 14.8N 36.7W 35 KT 48HR VT 13/1800Z 15.0N 39.1W 40 KT 72HR VT 14/1800Z 16.0N 44.0W 45 KT 96HR VT 15/1800Z 18.0N 49.0W 50 KT 120HR VT 16/1800Z 21.0N 54.5W 45 KT $$ FORECASTER BERG |
