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| #199612 (Received by flhurricane at: 10:37 PM 06.Jul.2008) TCDAT2 TROPICAL STORM BERTHA DISCUSSION NUMBER 16 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 1100 PM EDT SUN JUL 06 2008 THE SATELLITE PRESENTATION HAS GRADUALLY IMPROVED DURING THE PAST SEVERAL HOURS. THE CONVECTION IS SYMMETRIC ABOUT THE CENTER WHILE THE OUTFLOW HAS BEEN EXPANDING WESTWARD...TYPICAL OF AN INTENSIFYING CYCLONE. FURTHERMORE...CONSECUTIVE MICROWAVE DATA SHOW A WELL DEFINED RING OF DEEP CONVECTION...OR EYE-LIKE FEATURE... WHICH IS GRADUALLY BECOMING ALIGNED VERTICALLY. THIS COULD EVENTUALLY BE THE PRECURSOR OF AN EYE FORMATION. DVORAK T-NUMBERS HAVE INCREASED AND NOW SUPPORT AN INITIAL INTENSITY OF 55 KNOTS. THE OCEAN IS PLENTY WARM AHEAD OF BERTHA SO THE SHEAR WILL BE THE MAIN PRIMARY LARGE SCALE FACTOR CONTROLLING THE FUTURE INTENSITY. WE ARE NOT CONSIDERING EYEWALL CYCLES AT THIS TIME...IN CASE AN EYE FORMS. BECAUSE THE SHEAR IS EXPECTED TO BE WEAK FOR THE NEXT DAY OR TWO... STRENGTHENING IS INDICATED AND BERTHA COULD BECOME A HURRICANE ON MONDAY. THEREAFTER...THE SHEAR IS EXPECTED TO FLUCTUATE SO NO IMPORTANT CHANGES IN INTENSITY ARE FORECAST. THE CENTER IS A LITTLE FARTHER NORTH AS IT APPEARS TO BE REALIGNING WITH THE MID-LEVEL VORTEX. THIS IS NOT A CHANGE IN TRACK SINCE BERTHA IS STILL MOVING TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT 17 KNOTS. A WEAKNESS OF THE SUBTROPICAL RIDGE ALONG 50 TO 55 DEGREES WEST WILL PROBABLY CAUSE BERTHA TO BEGIN TO SLOW DOWN SOON. THE SUBTROPICAL RIDGE IS EXPECTED TO REBUILD SOME IN A DAY OR TWO CAUSING BERTHA TO CONTINUE ON A WEST-NORTHWEST TO NORTHWEST TRACK. BY THE END OF THE FORECAST PERIOD...THE STEERING CURRENTS ARE FORECAST TO WEAKEN AGAIN AND BERTHA SHOULD SLOW DOWN CONSIDERABLY AS INDICATED BY SOME GLOBAL MODELS. THE OFFICIAL FORECAST IS CONSISTENT WITH MOST OF THE TRACK GUIDANCE WHICH IS IN MUCH BETTER AGREEMENT TONIGHT. NO NEED TO DISCUSS EVERY MODEL. FORECAST POSITIONS AND MAX WINDS INITIAL 07/0300Z 18.6N 48.9W 55 KT 12HR VT 07/1200Z 19.3N 51.5W 60 KT 24HR VT 08/0000Z 20.0N 54.5W 70 KT 36HR VT 08/1200Z 21.0N 57.0W 70 KT 48HR VT 09/0000Z 22.0N 59.5W 70 KT 72HR VT 10/0000Z 24.0N 62.0W 70 KT 96HR VT 11/0000Z 27.0N 64.5W 70 KT 120HR VT 12/0000Z 30.0N 65.5W 70 KT $$ FORECASTER AVILA |
