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| #52226 (Received by flhurricane at: 4:43 PM 17.Oct.2005) TCDAT4 TROPICAL STORM WILMA DISCUSSION NUMBER 9 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 PM EDT MON OCT 17 2005 A RECONNAISSANCE AIRCRAFT HAS JUST ARRIVED IN THE CENTER OF WILMA...FINDING A MINIMUM PRESSURE OF 989 MB...AND PEAK 850 MB FLIGHT-LEVEL WINDS OF 51 KT IN THE SOUTHEAST QUADRANT. WHILE THIS MINIMUM PRESSURE OFTEN CORRESPONDS TO NEAR HURRICANE INTENSITY... ENVIRONMENTAL PRESSURES ARE UNUSUALLY LOW...FLATTENING THE PRESSURE GRADIENT. THOUGH THE OVERALL AMOUNT OF DEEP CONVECTION HAS DECREASED WITH THE DIURNAL MINIMUM...BANDING CONTINUES TO DEVELOP AND NEW CONVECTION IS GOING OFF DIRECTLY OVER THE CENTER. WILMA CONTINUES TO MAINTAIN A STRONG UPPER-LEVEL OUTFLOW PATTERN...ONE WHICH IS FORECAST TO PERSIST BY THE GLOBAL MODELS. CONTINUED DEVELOPMENT IS EXPECTED...WITH BOTH THE SHIPS AND GFDL MODELS MAKING WILMA A MAJOR HURRICANE IN THE NORTHWESTERN CARIBBEAN. ONCE WILMA GETS INTO THE GULF OF MEXICO...THE UPPER FLOW WILL BECOME MORE HOSTILE AS SHEAR INCREASES...AND SOME WEAKENING IS THEREFORE EXPECTED AT THAT TIME. WILMA CONTINUES TO DRIFT MOSTLY SOUTHWARD...OR 190/2. CERTAINLY THERE HAS BEEN MORE SOUTHWARD MOTION THAN ANTICIPATED...WITH THIS POSSIBLY ASSOCIATED WITH THE CONVECTIVE ASYMMETRY OBSERVED OVERNIGHT AND THROUGH MUCH OF THE DAY TODAY. HOWEVER...THE CORE CONVECTION HAS BECOME MORE SYMMETRIC THIS AFTERNOON...AND I AM EXPECTING WILMA TO SOON BEGIN MOVING SLOWLY WESTWARD IN BETTER ACCORD WITH THE GUIDANCE. THE BASIC SYNOPTIC REASONING IS UNCHANGED FROM PREVIOUS ADVISORIES. HIGH PRESSURE OVER THE WESTERN GULF OF MEXICO IS EXPECTED TO WEAKEN AS THE LARGE LOW OFF OF BAJA CALIFORNIA MOVES EASTWARD. THIS IS EXPECTED TO ALLOW WILMA TO GRADUALLY TURN NORTHWESTWARD OVER THE NEXT TWO TO THREE DAYS. FOR REASONS UNKNOWN...THE MODEL GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT THIS AFTERNOON. THE 12Z RUNS OF THE NOGAPS AND UKMET MODELS HAVE SHIFTED NORTHWARD BY ABOUT 200 MILES AND NO LONGER DRIVE WILMA INTO BELIZE. THE GFS AND GFDL...ON THE OTHER HAND...HAVE SHIFTED WESTWARD...RESULTING IN A RATHER NARROW GUIDANCE ENVELOPE RATHER CLOSE TO THE PREVIOUS OFFICIAL FORECAST. CONSEQUENTLY...LITTLE CHANGE HAS BEEN MADE TO THE PREVIOUS ADVISORY...EXCEPT THAT BY THE VERY END OF THE FORECAST PERIOD WILMA IS EXPECTED TO BE ENCOUNTERING WESTERLY FLOW IN THE GULF OF MEXICO THAT SHOULD FORCE A FAIRLY SHARP RIGHT TURN. HOW SHARP A TURN WILMA TAKES IS OBVIOUSLY OF INTEREST TO ALL ALONG THE EASTERN GULF OF MEXICO...BUT IT IS FAR TOO EARLY TO IDENTIFY SPECIFIC AREAS AT GREATEST RISK. FORECASTER FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 17/2100Z 15.8N 79.9W 45 KT 12HR VT 18/0600Z 15.9N 80.7W 55 KT 24HR VT 18/1800Z 16.3N 81.8W 65 KT 36HR VT 19/0600Z 16.9N 82.8W 75 KT 48HR VT 19/1800Z 17.7N 84.0W 85 KT 72HR VT 20/1800Z 19.5N 85.5W 100 KT 96HR VT 21/1800Z 21.5N 86.5W 100 KT 120HR VT 22/1800Z 23.5N 85.0W 90 KT |
