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#199030 (Received by flhurricane at: 4:40 PM 04.Jul.2008) TCDAT2 TROPICAL STORM BERTHA DISCUSSION NUMBER 7 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 500 PM EDT FRI JUL 04 2008 BERTHA HAD A RATHER RAGGED APPEARANCE IN SATELLITE IMAGERY AROUND MID-DAY...HOWEVER...SINCE THEN A NEW BURST OF CONVECTION WITH VERY COLD CLOUD TOPS HAS DEVELOPED NEAR AND NORTH OF THE CENTER. DVORAK INTENSITY ESTIMATES FROM TAFB AND SAB STILL SUPPORT AN INITIAL INTENSITY OF 45 KT. LITTLE CHANGE IN INTENSITY IS EXPECTED DURING THE NEXT 24 HOURS AS BERTHA TRAVERSES OVER COOLER WATERS. THEREAFTER...THE SSTS WILL INCREASE ALONG THE PROJECTED TRACK...HOWEVER...VERTICAL SHEAR IS FORECAST TO INCREASE IN THE 3-5 DAY TIME PERIOD. THE NEW INTENSITY FORECAST IS UNCHANGED FROM THE PREVIOUS ADVISORY AND KEEPS BERTHA'S INTENSITY BELOW HURRICANE STRENGTH. THE GFDL CONTINUES TO SHOW BERTHA REACHING HURRICANE STATUS...BUT THE SHIPS MODEL HAS BACKED OFF A LITTLE...AND IS IN LINE WITH THE OFFICIAL FORECAST. BERTHA CONTINUES TO ACCELERATE AND IS NOW MOVING WEST-NORTHWESTWARD OR 290/16. LITTLE CHANGE IN HEADING IS EXPECTED DURING THE NEXT 2-3 DAYS AS THE STORM REMAINS SOUTH OF A MID-TROPOSPHERIC RIDGE. THE GFDL TRACK HAS NOW SHIFTED WESTWARD AND HAS JOINED THE REMAINDER OF THE MODEL GUIDANCE...EXCEPT FOR THE HWRF WHICH STILL INSISTS ON A NORTHWESTWARD TURN. THE NEW TRACK FORECAST REMAINS VERY SIMILAR TO THE PREVIOUS ADVISORY THROUGH 48 HOURS BUT HAS SHIFTED FARTHER SOUTHWESTWARD AT DAYS 3-5... IN GOOD AGREEMENT WITH THE LATEST MODEL CONSENSUS AND THE ECMWF. FORECAST POSITIONS AND MAX WINDS INITIAL 04/2100Z 15.5N 31.6W 45 KT 12HR VT 05/0600Z 16.2N 34.2W 45 KT 24HR VT 05/1800Z 16.8N 37.8W 45 KT 36HR VT 06/0600Z 17.4N 41.5W 50 KT 48HR VT 06/1800Z 17.9N 45.2W 55 KT 72HR VT 07/1800Z 19.2N 51.5W 60 KT 96HR VT 08/1800Z 21.5N 56.0W 60 KT 120HR VT 09/1800Z 23.5N 60.5W 60 KT $$ FORECASTER BROWN |