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#105802 (Received by flhurricane at: 5:03 AM 24.Aug.2006) TCDAT4 TROPICAL STORM DEBBY DISCUSSION NUMBER 11 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL042006 500 AM EDT THU AUG 24 2006 CONVECTION HAS BEEN PULSING IN THE SOUTHERN AND WESTERN PORTION OF THE STORM WITH A SYMMETRIC OUTFLOW PATTERN FORMING. THE INITIAL INTENSITY WILL BE CONSERVATIVELY KEPT AT 40 KT IN BETWEEN SUBJECTIVE DVORAK INTENSITY ESTIMATES OF 35-45 KT. A GRADUAL STRENGTHENING APPEARS LIKELY DUE TO SLOWLY INCREASING SSTS AND FAIRLY LIGHT SOUTHERLY SHEAR IN THE NEXT DAY OR SO. THEREAFTER... SSTS RISE A BIT FASTER BUT GLOBAL MODELS SUGGEST THAT SOUTHERLY SHEAR WILL INCREASE. INTENSITY GUIDANCE DIVERGES BEYOND TWO DAYS... AS SHIPS NEVER MAKES DEBBY A HURRICANE WHILE THE GFDL INTENSIFIES THE SYSTEM INTO A CATEGORY 2 HURRICANE BY DAY THREE. THE INTENSITY FORECAST IS A COMPROMISE BETWEEN THESE MODELS AND SIMILAR TO THE PREVIOUS FORECAST. THE INITIAL MOTION ESTIMATE IS ABOUT THE SAME...300/17. THIS GENERAL TRACK IS ANTICIPATED IN THE NEAR-TERM AS THE CYCLONE MOVES IN BETWEEN A BUILDING MIDDLE-LEVEL HIGH TO THE NORTH-NORTHEAST AND A MIDDLE TO UPPER-LEVEL TROUGH TO THE SOUTHWEST. BEYOND 24-36 HOURS... A BREAK IN THE TROPICAL RIDGE FORMS NEAR 55W. THIS BREAK SHOULD ALLOW THE TROPICAL CYCLONE TO MOVE MORE TO THE NORTHWEST THEN NORTH... THOUGH MODELS DISAGREE ON HOW FAST TO TAKE DEBBY NORTHWARD. THE GFDL IS THE FASTEST MODEL.... SHOOTING THE STORM INTO THE MID-LATITUDES NORTH OF 40N IN ABOUT 5 DAYS. THE NOGAPS IS CONSIDERABLY SLOWER... SHOWING A WEAKER TROUGH AND KEEPING DEBBY SOUTH OF 32N THROUGHOUT THE PERIOD. THE MODELS ARE GENERALLY A LITTLE FASTER THAN 6 HOURS AGO... AND THE OFFICIAL FORECAST FOLLOWS SUIT... A BIT SOUTH OF THE GUNS CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 24/0900Z 19.6N 36.3W 40 KT 12HR VT 24/1800Z 20.6N 38.7W 40 KT 24HR VT 25/0600Z 21.8N 41.6W 45 KT 36HR VT 25/1800Z 23.0N 44.5W 50 KT 48HR VT 26/0600Z 24.5N 47.0W 55 KT 72HR VT 27/0600Z 27.5N 50.5W 65 KT 96HR VT 28/0600Z 30.5N 51.0W 65 KT 120HR VT 29/0600Z 34.5N 49.5W 65 KT |