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#201607 (Received by flhurricane at: 10:52 AM 18.Jul.2008) TCDAT2 TROPICAL STORM BERTHA DISCUSSION NUMBER 62 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 1100 AM EDT FRI JUL 18 2008 BERTHA HAS A WELL-DEVELOPED CLOUD PATTERN...OCCASIONALLY SHOWING SIGNS OF TRYING TO FORM AN EYE. QUIKSCAT DATA FROM EARLIER SUGGEST MAXIMUM WINDS OF 50-55 KT AND...SINCE SATELLITE CLASSIFICATIONS ALSO SUPPORT 55 KT...THE INTENSITY IS RAISED TO 55 KT FOR THIS ADVISORY. KUDOS GO TO THE GFDL/HWRF MODELS WHICH CORRECTLY FORECAST THE RE-INTENSIFICATION OF THE STORM. HOWEVER...SSTS ARE NOW DECREASING IN THE PATH OF THE STORM...WHICH COULD LIMIT ANY FUTURE GROWTH OF THE SYSTEM. IN ABOUT 24 HOURS...SSTS QUICKLY DROP AND VERTICAL SHEAR IS FORECAST TO INCREASE...SO THIS COMBINATION SHOULD BEGIN A WEAKENING OF THE STORM. THE OFFICIAL FORECAST IS CLOSE TO THE INTENSITY CONSENSUS. THE INITIAL MOTION OF THE STORM IS 040/16. THIS GENERAL MOTION WITH AN INCREASE IN FORWARD SPEED IS EXPECTED AS THE STORM IS CAUGHT BETWEEN A BUILDING HIGH TO THE SOUTHEAST AND THE MIDDLE-LATITUDE WESTERLIES. IN ABOUT 36 HOURS...COLD NORTH ATLANTIC WATERS AND INTERACTIONS WITH A MIDDLE-LATITUDE TROUGH SHOULD START THE EXTRATROPICAL TRANSITION PROCESS. TRACK GUIDANCE IS ABOUT AS TIGHTLY CLUSTERED AS IT CAN BE AND THE OFFICIAL FORECAST IS CLOSE TO THE MIDDLE OF THE GUIDANCE. FORECAST POSITIONS AND MAX WINDS INITIAL 18/1500Z 36.2N 52.3W 55 KT 12HR VT 19/0000Z 38.1N 50.1W 55 KT 24HR VT 19/1200Z 41.0N 46.8W 55 KT 36HR VT 20/0000Z 44.2N 43.1W 50 KT...BECOMING EXTRATROPICAL 48HR VT 20/1200Z 48.0N 38.5W 45 KT...EXTRATROPICAL 72HR VT 21/1200Z 57.0N 25.5W 45 KT...EXTRATROPICAL 96HR VT 22/1200Z...ABSORBED $$ FORECASTER BLAKE |