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| #52152 (Received by flhurricane at: 5:14 AM 17.Oct.2005) TCDAT4 TROPICAL STORM WILMA DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT MON OCT 17 2005 A TREMENDOUS BURST OF DEEP CONVECTION...WITH TOPS AS COLD AS -87C TO -89C... HAS DEVELOPED DURING THE PAST 6 HOURS NEAR AND TO THE SOUTH AND SOUTHWEST OF THE ALLEGED CENTER OF NOW TROPICAL STORM WILMA. MICROWAVE SATELLITE DATA ALONG WITH WIND DATA FROM NOAA BUOY 42057 INDICATE THAT THE CYCLONE HAS BEEN MOVING SLOWLY SOUTH OR SOUTHWESTWARD. HOWEVER... THE LOW-LEVEL CENTER DOES NOT APPEAR TO BE LOCATED IN THE CENTER OF THE DEEP CONVECTION... RATHER IT IS LIKELY LOCATED NEAR THE NORTHEASTERN EDGE OF THE -50C CLOUD TOPS. SATELLITE INTENSITY ESTIMATES ARE A CONSENSUS T2.5 FROM TAFB... SAB...AND AFWA... AND A UW-CIMSS 3-HR AVERAGE ODT INTENSITY ESTIMATE AT 17/0545Z WAS T2.8/41 KT. IN ADDITION... GRADIENT WIND CALCULATIONS USING THE CENTRAL PRESSURE AND NEARBY PRESSURE VALUES FROM THE NOAA BUOY AND JAMAICA SUPPORT 35-KT WINDS SOMEWHERE WITHIN 60 NMI OF THE CENTER. IF ANY 35-KT WINDS EXISTS... THEN THEY ARE LIKELY IN THE SOUTHWESTERN QUADRANT WHERE THE STRONG CONVECTION IS LOCATED. THEREFORE... THE INITIAL INTENSITY IS SET AT 35 KT... WHICH MAKES WILMA THE 21ST NAMED TROPICAL STORM OF THE VERY BUSY 2005 ATLANTIC HURRICANE SEASON. THIS TIES THE RECORD SET BACK IN 1933. THE INITIAL MOTION IS AN UNCERTAIN 235/03. THE GENERAL TREND IN THE CONVECTIVE CLOUD PATTERN HAS BEEN TO SHIFT SLOWLY SOUTH OR SOUTHWESTWARD AS MID-LEVEL RIDGING TO THE NORTH OVER FLORIDA AND CUBA APPEAR TO BE THE ONLY STEERING FLOW AVAILABLE. BUT ON A LARGER SCALE... WILMA REMAINS TRAPPED BETWEEN TO HIGH PRESSURE CELLS TO THE NORTHWEST AND EAST OF THE CYCLONE. THE 00Z GLOBAL MODELS AND THE MAJORITY OF THE NHC MODEL GUIDANCE HAS SHIFTED SIGNIFICANTLY WESTWARD OR TO THE LEFT OF THE PREVIOUS GUIDANCE AND FORECAST TRACK. THE ONLY MODELS NOT CLOSE TO THE NHC CONSENSUS OR GUNA MODEL ARE THE ECMWF... CANADIAN... AND THE GFS 10-MEMBER ENSEMBLE MODELS. THE ECWMF HAS BEEN REMARKABLY CONSISTENT WITH ITS TRACK THE PAST 5 DAYS IN MOVING THE CYCLONE TOWARD THE YUCATAN CHANNEL. IT ALSO WAS THE ONLY MODEL TO EARLY AND ACCURATELY PREDICT CYCLOGENESIS. THE ECMWF AND THE CANADIAN MODELS ARE ALSO THE ONLY MODELS THAT DO NOT LOSE THE SHORTWAVE TROUGH LOCATED OVER THE CENTRAL U.S. THAT IS CURRENTLY MOVING EASTWARD THROUGH THE AXIS OF THE LONGWAVE RIDGE. UPPER-AIR DATA AT 00Z INDICATE A GOOD THERMAL PATTERN ASSOCIATED WITH THIS TROUGH... WHICH ONLY THE ECMWF AND CANADIAN HAVE PICKED UP ON. THE SHORTWAVE IS FORECAST TO DIG SOUTHEASTWARD DOWN THE EAST SIDE OF THE LONGWAVE RIDGE AND GRADUALLY WEAKEN/ERODE THE SUBTROPICAL RIDGE ACROSS FLORIDA... CUBA...AND THE EASTERN GULF OF MEXICO BY 48 HOURS. ALSO... THE DEEP-LAYER LOW OFF THE COAST OF BAJA CALIFORNIA IN COMBINATION WITH THE DEEP LOW OVER THE CANADIAN MARITIMES SHOULD HELP MAINTAIN A BLOCKING-TYPE PATTERN ACROSS THE U.S.... WHICH MEANS THE STEERING FLOW SHOULD CHANGE LITTLE FOR AT LEAST THE NEXT 2-3 DAYS. THE OFFICIAL FORECAST TRACK WAS ONLY SHIFTED SLIGHTLY TO THE LEFT... OR WEST... OF THE PREVIOUS TRACK OUT OF RESPECT FOR THE CONSISTENT ECMWF MODEL... AND ALSO UNTIL THE EVOLUTION OF THE SHORTWAVE TROUGH OVER THE CENTRAL U.S. BECOMES MORE CERTAIN BY LATER TODAY OR TONIGHT. SOME MID-LEVEL DRY AIR AND SHEAR ARE STILL UNDERCUTTING THE IMPRESSIVE UPPER-LEVEL OUTFLOW PATTERN. HOWEVER... THESE ADVERSE CONDITIONS APPEAR TO BE SLOWLY DIMINISHING BASED ON CONVENTIONAL WATER VAPOR IMAGERY AND A 17/0155Z SSMI WATER VAPOR ANALYSIS. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO REMAIN VERY FAVORABLE FOR CONTINUED INTENSIFICATION THROUGHOUT THE FORECAST PERIOD. ONLY POSSIBLE LAND INTERACTION WITH THE NORTHEASTERN YUCATAN PRECLUDES FORECASTING WILMA TO BECOME A MAJOR HURRICANE BY 120 HOURS. THE OFFICIAL INTENSITY FORECAST IS A BLEND OF THE LESS ROBUST SHIPS MODEL AND THE VERY BULLISH GFDL MODEL... WITH THE LATTER MODEL MAKING WILMA A 109-KT HURRICANE BY 60 HOURS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 17/0900Z 17.2N 79.7W 35 KT 12HR VT 17/1800Z 17.1N 80.3W 40 KT 24HR VT 18/0600Z 17.2N 81.1W 50 KT 36HR VT 18/1800Z 17.4N 82.0W 60 KT 48HR VT 19/0600Z 17.8N 83.3W 70 KT 72HR VT 20/0600Z 18.5N 85.0W 80 KT 96HR VT 21/0600Z 20.0N 86.5W 90 KT...NEAR NORTHEAST YUCATAN 120HR VT 22/0600Z 22.5N 87.5W 90 KT...NEAR NORTHEAST YUCATAN |
