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| #45635 (Received by flhurricane at: 5:03 AM 13.Sep.2005) TCDAT1 TROPICAL STORM OPHELIA DISCUSSION NUMBER 28 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT TUE SEP 13 2005 SATELLITE IMAGERY AND RADAR DATA INDICATE THAT OPHELIA IS GRADUALLY BECOMING BETTER ORGANIZED. THE CONVECTIVE TOPS HAVE COOLED... ESPECIALLY TO THE SOUTHEAST OF THE CENTER...AND THE CONVECTION IS STARTING TO WRAP AROUND THE WEST SIDE OF THE CIRCULATION. THE LAST AIR FORCE RESERVE HURRICANE HUNTER IN THE STORM REPORTED A CENTRAL PRESSURE OF 990 MB...WITH MAXIMUM FLIGHT-LEVEL WINDS BETWEEN 60-65 KT AND SURFACE WINDS OF 55 KT FROM DROPSONDES. THIS WOULD NOT NORMALLY SUPPORT 60 KT SURFACE WINDS...BUT THE INITIAL INTENSITY WILL REMAIN 60 KT BASED ON THE IMPROVED ORGANIZATION SINCE THE AIRCRAFT LEFT. OPHELIA HAS MOVED LITTLE SINCE 00Z...WITH THE CENTER MEANDERING AROUND INSIDE THE BROAD CIRCULATION. WATER VAPOR IMAGERY SHOWS THE MID/UPPER-LEVEL RIDGE AXIS NORTH OF OPHELIA IS NOW ALONG 81W... MOVING STEADILY EASTWARD. ONCE THE RIDGE MOVES EAST OF 78W...WHICH SHOULD TAKE 12-18 HR...OPEHLIA SHOULD BEGIN A SLOW NORTHWARD MOTION THROUGH ABOUT 36 HR. AFTER THAT...INCREASING DEEP-LAYER SOUTHWESTERLY FLOW SHOULD TURN OPHELIA NORTHEASTWARD WITH SOME ACCELERATION. MODEL GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT ON THIS SCENARIO...WITH THE GFDL AND THE GLOBAL MODELS FORECASTING OPHELIA TO BE NEAR CAPE FEAR IN 30-36 HR...FOLLOWED BY PASSAGE ACROSS EXTREME EASTERN NORTH CAROLINA INTO THE ATLANTIC. THE NEW FORECAST TRACK IS AN UPDATE OF THE PREVIOUS PACKAGE THROUGH 48 HR...ALONG THE LEFT SIDE OF THE MAIN ENVELOPE OF GUIDANCE. IT IS ALSO FASTER THAN THE PREVIOUS FORECAST...ALTHOUGH NOT AS FAST AS MOST OF THE GLOBAL MODELS. IT SHOULD BE NOTED THAT SOME WESTERLY COMPONENT OF MOTION IS STILL POSSIBLE IN THE NEXT 12-18 HR BEFORE THE NORTHWARD TURN OCCURS. THE INTENSITY FORECAST REMAINS SOMEWHAT PROBLEMATIC. WHILE THE CORE OF OPHELIA IS OVER THE GULF STREAM WITH SEA SURFACE TEMPERATURES OF NEAR 28C...MUCH OF THE WATER ON EITHER SIDE OF THE GULF STREAM IS 27C OR COLDER. WATER VAPOR IMAGERY CONTINUES TO INDICATE MID/UPPER-LEVEL DRY AIR SURROUNDING THE STORM...AND SURFACE DATA SHOWS COOLER AND DRIER AIR TRYING TO ENTRAIN INTO THE SOUTHWEST SIDE. COMBINE THESE FACTORS WITH THE LARGE RADIUS OF MAXIMUM WINDS AND IT SUGGESTS THAT OPHELIA SHOULD NOT STRENGTHEN VERY QUICKLY EVEN THOUGH THE UPPER-LEVEL WINDS ARE GENERALLY FAVORABLE. NONE OF THE INTENSITY GUIDANCE CALLS FOR MORE THAN 67 KT WINDS...SO THE INTENSITY FORECAST WILL ONLY STRENGTHEN OPHELIA BACK TO 65 KT. THAT BEING SAID...IF THE STORM CONTINUES TO GENERATE CONVECTION AS STRONG AS CURRENTLY OCCURRING THERE IS A CHANCE IT COULD GET A LITTLE STRONGER. AFTER CROSSING NORTH CAROLINA...OPHELIA SHOULD WEAKEN AS IT MOVES INTO THE WESTERLIES AND BECOME EXTRATROPCIAL BY 120 HR. FORECASTER BEVEN FORECAST POSITIONS AND MAX WINDS INITIAL 13/0900Z 32.0N 78.0W 60 KT 12HR VT 13/1800Z 32.4N 78.2W 65 KT 24HR VT 14/0600Z 33.1N 78.2W 65 KT 36HR VT 14/1800Z 34.0N 77.8W 65 KT 48HR VT 15/0600Z 34.9N 76.9W 65 KT...INLAND 72HR VT 16/0600Z 36.5N 74.0W 55 KT...OVER WATER 96HR VT 17/0600Z 39.0N 69.0W 50 KT 120HR VT 18/0600Z 44.0N 60.0W 40 KT...EXTRATROPICAL |
