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| #52574 (Received by flhurricane at: 4:37 AM 20.Oct.2005) TCDAT4 HURRICANE WILMA DISCUSSION NUMBER 20 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT THU OCT 20 2005 AS ANTICIPATED...WILMA IS GOING THROUGH THE WEAKENING PHASE OF AN EYEWALL CYCLE. THIS IS BASED ON MICROWAVE DATA AND OBSERVATIONS FROM A RECONNAISSANCE PLANE WHICH REPORTED EXCELLENT RADAR PRESENTATION OF CONCENTRIC EYEWALLS OF 4 AND 40 N MI IN DIAMETER RESPECTIVELY. THE PLANE ALSO OBSERVED TWO MAXIMUM WIND BANDS...ONE WITH WINDS OF 121 KNOTS...AND A MINIMUM PRESSURE OF 903 MB MEASURED BY A SONDE...BUT WITH 23 KNOTS AT THE SURFACE. THE PRESSURE COULD THEN BE A FEW MILLIBARS LOWER. SATELLITE IMAGES INDICATE THAT THE CLOUD PATTERN IS NOT AS SPECTACULAR AS IT WAS 12 TO 18 HOURS AGO AND IN FACT...THE EYE IS OBSCURED AT THIS TIME. THE INITIAL INTENSITY IS ADJUSTED DOWN TO 130 KNOTS. THIS MAY BE AN OVERESTIMATE SINCE THE MAXIMUM WINDS REPORTED SO FAR ARE 121 KNOTS. HOWEVER...WE ARE ASSUMING THAT THE PLANE HAS NOT SAMPLED THE ENTIRE CIRCULATION. WE DO NOT KNOW EXACTLY WHEN AND IF THE STRENGTHENING PHASE OF THE EYEWALL REPLACEMENT CYCLE WILL BEGIN. SINCE IT IS ASSUMED THAT IT WILL OCCUR WITHIN THE NEXT 12 TO 24 HOURS...RE-INTENSIFICATION IS FORECAST DURING THIS PERIOD. I WOULD NOT BE SURPRISED IF WE SEE THE FORMATION OF A LARGE EYE LATER TODAY. THEREAFTER...A PORTION OF THE CIRCULATION WILL BE INTERACTING WITH THE YUCATAN PENINSULA AND THERE WILL BE INCREASING WIND SHEAR. WILMA SHOULD THEN BEGIN A STEADY WEAKENING TREND. THE EXPECTED NORTHWEST TURN HAS NOT MATERIALIZED YET AND THE AVERAGE MOTION OF WILMA IS STILL 295 DEGREES AT 7 KNOTS. HOWEVER...THE NORTHWEST MOTION SHOULD BEGIN SOON AS THE SHORT WAVE OVER THE WEST CENTRAL UNITED STATES ADVANCES RAPIDLY EASTWARD. THIS WAVE IS EXPECTED TO CREATE A WEAKNESS OVER THE GULF OE MEXICO AND WILMA SHOULD TURN TO THE NORTHWEST AND NORTH TOWARD THE WEAKNESS. THE SHORT-WAVE IS EXPECTED TO AMPLIFY AND BRING THE WESTERLY FLOW SOUTH ENOUGH TO CARRY WILMA TOWARD THE NORTHEAST. BEFORE THE WESTERLIES BECOME ESTABLISHED...THE STEERING CURRENTS ARE EXPECTED TO BE WEAK. WILMA WILL LIKELY MEANDER FOR A DAY OR SO OVER NORTHEASTERN YUCATAN OR THE YUCATAN CHANNEL BEFORE TAKING OFF TOWARD THE NORTHEAST AS IN A TYPICAL RECURVATURE PATTERN. TRACK GUIDANCE IS SHOWING THE USUAL VARIABILITY BUT THE OVERALL MODEL CONSENSUS IS TO KEEP WILMA MOVING VERY SLOWLY NEAR OR OVER NORTHEASTERN YUCATAN FOR THE NEXT TWO DAYS AND THEN SHARPLY TURNING THE HURRICANE TOWARD THE NORTHEAST. IT IS FAIR TO SAY THAT BY DAY FIVE...WILMA SHOULD BEGIN TO ACQUIRE EXTRATROPICAL CHARACTERISTICS BY JUDGING THE EXPANSION OF THE WIND FIELD AND THE FRONTAL LIKE MOISTURE PATTERN IN MODELS. FORECASTER AVILA FORECAST POSITIONS AND MAX WINDS INITIAL 20/0900Z 18.3N 85.0W 130 KT 12HR VT 20/1800Z 18.9N 85.8W 135 KT 24HR VT 21/0600Z 20.0N 86.5W 145 KT 36HR VT 21/1800Z 21.0N 87.0W 145 KT 48HR VT 22/0600Z 22.0N 86.5W 125 KT 72HR VT 23/0600Z 24.0N 84.5W 110 KT 96HR VT 24/0600Z 27.0N 80.0W 80 KT 120HR VT 25/0600Z 37.1N 70.0W 65 KT...BECOMING EXTRATROPICAL |
