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| #57544 (Received by flhurricane at: 3:37 AM 19.Nov.2005) TCDAT2 TROPICAL STORM GAMMA DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 4 AM EST SAT NOV 19 2005 SINCE THE LAST RECON FLIGHT... DEEP CONVECTION HAS REDEVELOPED OVER AND NORTH OF THE LOW-LEVEL CENTER... AND HAS ALSO BECOME BETTER ORGANIZED. THE INITIAL INTENSITY REMAINS AT 40 KT FOR THIS ADVISORY BASED ON A BLEND OF SATELLITE INTENSITY ESTIMATES OF T3.0/45 KT FROM TAFB AND T2.5/35 KT FROM SAB AND AFWA. THE INITIAL MOTION ESTIMATE IS 325/05. UPPER-AIR DATA AT 00Z... ALBEIT LIMITED ACROSS THE CARIBBEAN AREA EXCEPT FOR BELIZE... INDICATE A BREAK IN THE 500 MB AND 400 MB RIDGE AXES ACROSS THE NORTHWESTERN CARIBBEAN SEA...YUCATAN CHANNEL... WESTERN CUBA AND SOUTHEASTERN GULF OF MEXICO. A WEAKNESS IN THE RIDGE TO THE NORTH OF GAMMA IS ALSO BEGINNING TO APPEAR AT THE 700 MB LEVEL. THE COMBINATION OF THE WEAKENING RIDGE ALONG 85W LONGITUDE AND THE MODERATE TO STRONG UPPER-LEVEL SOUTHERLY FLOW ACROSS THE WESTERN CARIBBEAN SHOULD OPEN AN ALLEY FOR GAMMA TO MOVE NORTHWARD THROUGH OVER THE NEXT COUPLE OF DAYS. AFTER THAT... A SERIES OF SHORTWAVE TROUGHS CURRENTLY OVER THE U.S. PLAINS STATES ARE FORECAST BY ALL THE MODELS TO MERGE AND DEVELOP INTO A HIGH-AMPLITUDE TROUGH OVER THE EASTERN U.S. AND THE EASTERN GULF OF MEXICO BY 72 HOURS. THIS FEATURE IS EXPECTED TO INDUCE SOUTHWESTERLY TO WESTERLY STEERING FLOW NORTH OF 20N LATITUDE BY 60-72 HOURS... WHICH SHOULD RESULT IN GAMMA LIFTING OUT TO THE NORTHEAST ACROSS WESTERN CUBA... THE BAHAMAS... AND POSSIBLY SOUTH FLORIDA. THE GLOBAL MODELS DISSIPATE GAMMA OR KEEP IT TRAPPED IN THE WESTERN CARIBBEAN SEA DURING THE NEXT 5 DAYS... WHICH SEEMS UNREASONABLE GIVEN THE VERTICALLY DEEP CIRCULATION NOTED IN THE 00Z UPPER-AIR DATA. AS SUCH...THE OFFICIAL FORECAST TRACK LEANS MORE TOWARD THE GFDL SOLUTION SINCE THAT MODEL MAINTAINS A DEEP TROPICAL CYCLONE THROUGH 120 HOURS. SINCE SIGNIFICANT VERTICAL SHEAR IS FORECAST TO REMAIN ACROSS GAMMA THROUGHOUT THE PERIOD... ONLY SLIGHT INTENSIFICATION IS EXPECTED. THE OFFICIAL FORECAST IS A BLEND OF THE GFDL AND SHIPS MODELS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 19/0900Z 16.9N 86.2W 40 KT 12HR VT 19/1800Z 17.5N 86.7W 45 KT 24HR VT 20/0600Z 18.4N 86.8W 45 KT 36HR VT 20/1800Z 20.0N 86.3W 45 KT 48HR VT 21/0600Z 22.0N 84.3W 45 KT 72HR VT 22/0600Z 26.0N 79.0W 45 KT...BECOMING EXTRATROPICAL 96HR VT 23/0600Z 38.0N 67.0W 40 KT...EXTRATROPICAL 120HR VT 24/0600Z...ABSORBED BY LARGER EXTRATROPICAL LOW |
