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| #59802 (Received by flhurricane at: 4:17 AM 04.Dec.2005) TCDAT4 TROPICAL STORM EPSILON DISCUSSION NUMBER 20 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 4 AM EST SUN DEC 04 2005 WATER VAPOR IMAGERY SHOWS DRY AIR PENETRATING THE SOUTHWEST QUADRANT OF THE CIRCULATION UNDERNEATH THE CIRRUS CANOPY...AND THE EYEWALL CONVECTION HAS THINNED TO THE SOUTH OF THE CENTER. DATA T NUMBERS FROM TAFB AND SAB ARE NOW BELOW HURRICANE STRENGTH...AND EPSILON IS DOWNGRADED TO A TROPICAL STORM ON THIS BASIS. THE INITIAL MOTION IS 090/11. EPSILON CONTINUES TO BE EMBEDDED IN A WEAK WESTERLY STEERING CURRENT. A BAROCLINIC ZONE TO THE NORTHWEST OF EPSILON IS ALSO MOVING EASTWARD...BUT MORE RAPIDLY THAN THE TROPICAL CYCLONE. THIS ZONE IS FORECAST BY THE GLOBAL MODELS TO PASS NEAR BUT NORTH OF EPSILON IN ABOUT 36 HOURS OR SO...AFTER WHICH HIGH PRESSURE IS FORECAST TO BUILD IN...BLOCKING EPSILON'S PATH. MODEL GUIDANCE IS IN EXCELLENT AGREEMENT ON A SOUTHWESTWARD TURN AFTER 48 HOURS. THE UKMET IS STILL SOMETHING OF AN OUTLIER FOR THE FIRST 48 HOURS WITH AN EAST-NORTHEASTERLY TRACK. THE OFFICIAL FORECAST DISCOUNTS THE UKMET...WHICH MISSED YESTERDAY'S EASTWARD MOTION...AND IS BASED ON A CONSENSUS OF THE GFS...GFDL...AND NOGAPS MODELS. ON THE FORECAST TRACK...WATER TEMPERATURES WILL DECREASE ONLY SLIGHTLY OVER THE NEXT COUPLE OF DAYS...AND THE GFDL SHOWS LITTLE CHANGE IN STRENGTH DURING THIS TIME. EPSILON HAS CARVED OUT FOR ITSELF A LITTLE POCKET OF MODERATE SHEAR...OF ABOUT 20-25 KT ACCORDING TO THE LATEST ANALYSIS FROM UW/CIMSS. HIGHER VALUES EXIST IN THE NEAR ENVIRONMENT OF THE CYCLONE THOUGH...AND IF THE AFOREMENTIONED DRY AIR CONTINUES TO WEAKEN THE CORE CONVECTION THEN EPSILON COULD QUICKLY FIND ITSELF OVERTAKEN BY THE SHEAR AND DEGENERATE TO A NON-CONVECTIVE REMNANT LOW WITHIN A COUPLE OF DAYS. IT IS POSSIBLE THAT EPSILON COULD BECOME EXTRATROPICAL BEFORE THAT...WHEN THE BAROCLINIC ZONE APPROACHES IN ABOUT 36 HOURS. FORECASTER FRANKLIN FORECAST POSITIONS AND MAX WINDS INITIAL 04/0900Z 34.3N 40.4W 60 KT 12HR VT 04/1800Z 34.3N 38.4W 55 KT 24HR VT 05/0600Z 34.2N 36.3W 45 KT 36HR VT 05/1800Z 34.0N 34.4W 40 KT...EXTRATROPICAL 48HR VT 06/0600Z 33.0N 33.0W 35 KT...REMNANT LOW 72HR VT 07/0600Z 30.0N 35.0W 25 KT...REMNANT LOW 96HR VT 08/0600Z 26.0N 39.0W 25 KT...REMNANT LOW 120HR VT 09/0600Z 22.0N 44.0W 25 KT...REMNANT LOW |
