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#106157 (Received by flhurricane at: 11:21 PM 25.Aug.2006) TCDAT5 TROPICAL STORM ERNESTO DISCUSSION NUMBER 6...CORRECTED NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL052006 1100 PM EDT FRI AUG 25 2006 ...CORRECTED TO INDICATE NEAR JAMAICA AT 36 HOURS... SINCE THE RECONNAISSANCE AIRCRAFT DEPARTED FROM THE TROPICAL STORM...CONVECTION HAS DEEPENED AND EXPANDED...BUT IS STILL DISPLACED MOSTLY EAST OF THE LOW-LEVEL CENTER. THE UW-CIMSS SHEAR ANALYSES ESTIMATE ABOUT 15 KTS OF WESTERLY SHEAR CURRENTLY AFFECTING ERNESTO WITH STRONGER SHEAR TO THE NORTHWEST. IT HAS BEEN A BIT DIFFICULT TO DETERMINE THE LOW-LEVEL CENTER LOCATION AND CONSEQUENTLY THE INITIAL INTENSITY BASED UPON THE DVORAK SHEAR PATTERN. DUE TO THE DEEPENING CONVECTION AND DATA T-NUMBERS FROM TAFB AND SAB RANGING FROM 35 KT TO 45 KT...THE INITIAL INTENSITY HAS BEEN BUMPED UP TO 40 KT. RECONNAISSANCE AIRCRAFT WILL BE BACK IN TO INVESTIGATE ERNESTO AT 0600 UTC TO GET A BETTER HANDLE ON THE CURRENT POSITION AND INTENSITY. THE INITIAL MOTION IS 285/14. A LOW- TO MID-LEVEL RIDGE ACROSS THE SOUTHWEST ATLANTIC CONTINUES TO STEER ERNESTO ON A WEST-NORTHWEST TRACK AND SHOULD CONTINUE TO DO SO FOR THE NEXT 48 TO 72 HOURS...AND THE MODELS ARE IN TIGHT AGREEMENT DURING THIS PERIOD. THE TRACK FORECAST BECOMES A BIT TRICKY ON DAYS 4 AND 5...WHEN A WEAKNESS IN THE STEERING PATTERN DEVELOPS ACROSS THE CENTRAL GULF OF MEXICO FORECAST BY MOST OF THE MODELS. THE OFFICIAL TRACK FORECAST KEEPS ERNESTO ON A GENERAL NORTHWESTWARD TRACK OVER THE GULF OF MEXICO. CURRENTLY AN UPPER-LEVEL LOW IS SITUATED OVER EASTERN CUBA AND JAMAICA WITH STRONG WEST-SOUTHWESTERLY WINDS TO ITS SOUTHEAST. WATER VAPOR IMAGERY INDICATES THIS UPPER-LEVEL LOW IS MOVING RAPIDLY TO THE WEST-SOUTHWEST...AND THE MODELS ARE IN CLOSE AGREEMENT THAT THE LOW SHOULD END UP ALONG THE EASTERN COAST OF MAINLAND MEXICO IN 3 TO 4 DAYS. THIS SCENARIO SHOULD PROVIDE A VERY WEAK SHEAR ENVIRONMENT FOR ERNESTO TO STRENGTHEN...AND IN FACT THE SHIPS GUIDANCE FORECASTS THE SHEAR TO WEAKEN CONSIDERABLY IN 36-48 HOURS AND REMAIN WEAK THROUGH DAY 5. THE OFFICIAL INTENSITY FORECAST OVER THE GULF OF MEXICO IS NUDGED UPWARD...SINCE MOST OF THE INTENSITY GUIDANCE INDICATES AN EVEN STRONGER INTENSITY THAN SHOWN BELOW. FORECAST POSITIONS AND MAX WINDS INITIAL 26/0300Z 14.8N 69.1W 40 KT 12HR VT 26/1200Z 15.6N 71.1W 45 KT 24HR VT 27/0000Z 16.6N 73.7W 50 KT 36HR VT 27/1200Z 17.8N 76.4W 55 KT...NEAR JAMAICA 48HR VT 28/0000Z 19.0N 79.0W 60 KT 72HR VT 29/0000Z 22.0N 84.0W 70 KT 96HR VT 30/0000Z 24.0N 87.0W 80 KT 120HR VT 31/0000Z 26.0N 90.0W 85 KT |