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| #200024 (Received by flhurricane at: 10:40 PM 08.Jul.2008) TCDAT2 HURRICANE BERTHA DISCUSSION NUMBER 24 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 1100 PM EDT TUE JUL 08 2008 THERE HAS BEEN NO SIGNIFICANT CHANGE IN THE CLOUD PATTERN ASSOCIATED WITH BERTHA. THERE IS A LITTLE BIT OF SOUTHEASTERLY SHEAR AND MOST OF THE DEEP CONVECTION IS IN A WELL-DEFINED CYCLONICALLY CURVED CONVECTIVE BAND TO THE WEST OF THE CENTER. BASED ON DVORAK T-NUMBERS...THE BEST ESTIMATE OF THE INTENSITY IS 70 KNOTS. I AM NOT QUITE SURE IF BERTHA HAS GIVEN UP AND WILL CONTINUE TO WEAKEN. THE HURRICANE IS HEADING FOR WARMER WATERS AND LOWER SHEAR SO REINTENSIFICATION IS NOT OUT OF THE QUESTION. BECAUSE OF THE MIXED SIGNALS AMONG GUIDANCE...WITH THE SHIPS MODEL WEAKENING THE HURRICANE AND BOTH GFDL AND HWRF SUGGESTING SLIGHT STRENGTHENING...THE OFFICIAL FORECAST HAS OPTED TO KEEP BERTHA AS A 70 KT HURRICANE FOR THE NEXT 3 DAYS. THEREAFTER...THE SHEAR IS FORECAST TO INCREASE AND GRADUAL WEAKENING IS INDICATED. BERTHA HAS CONTINUED TO MOVE TOWARD THE NORTHWEST OR 310 DEGREES AT 10 KNOTS. A GRADUAL TURN TO THE NORTH IS EXPECTED BEYOND 48 HOURS AS THE MID-LEVEL RIDGE CURRENTLY NORTH OF THE CYCLONE WEAKENS AND A SHORT WAVE APPROACHES THE U.S. EAST COAST FROM THE WEST. HOWEVER...THIS GENERAL NORTHWARD MOTION BETWEEN 48 AND 120 HOURS IS EXPECTED TO BE PAINFULLY SLOW SINCE STEERING CURRENTS ARE FORECAST TO BE VERY WEAK. THERE WAS A SLIGHT CHANGE IN THE 00Z GUIDANCE. UNANIMOUSLY...THEY ALL SHIFTED A DEGREE OR TWO WESTWARD...INCLUDING THE HWRF WHICH WAS FARTHER EAST AND HAS NOW JOINED THE REST OF THE MODEL SUITE. THE OFFICIAL TRACK FORECAST WAS SHIFTED A LITTLE BIT TO THE WEST AND IS NOW ON THE RIGHT SIDE OF THE GUIDANCE ENVELOPE...IN FACT...JUST EAST OF THE GFDL AND THE HWRF. I DO NOT WANT TO CHANGE THE TRACK TOO MUCH SINCE I WOULD NOT BE SURPRISED IF THE GUIDANCE SHIFTS BACK TO THE EAST IN THE NEXT RUN. FORECAST POSITIONS AND MAX WINDS INITIAL 09/0300Z 23.1N 55.8W 70 KT 12HR VT 09/1200Z 24.0N 57.0W 70 KT 24HR VT 10/0000Z 25.5N 58.5W 70 KT 36HR VT 10/1200Z 27.0N 60.0W 70 KT 48HR VT 11/0000Z 28.0N 60.5W 70 KT 72HR VT 12/0000Z 30.0N 61.0W 70 KT 96HR VT 13/0000Z 31.5N 61.0W 65 KT 120HR VT 14/0000Z 33.5N 60.0W 60 KT $$ FORECASTER AVILA |
