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| #201200 (Received by flhurricane at: 4:52 PM 15.Jul.2008) TCDAT2 TROPICAL STORM BERTHA DISCUSSION NUMBER 51 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 500 PM EDT TUE JUL 15 2008 THE SATELLITE PRESENTATION OF BERTHA HAS DEGRADED A BIT OVER THE PAST FEW HOURS AS THE EYE HAS BECOME LESS DISTINCT. HOWEVER... THERE HAS BEEN NO CHANGE IN THE SATELLITE CLASSIFICATIONS...AND THE CURRENT INTENSITY WILL BE KEPT AT 60 KT FOR THIS ADVISORY...WHICH MIGHT BE A LITTLE GENEROUS. IT APPEARS THAT THE STORM HAS ABOUT A DAY LEFT TO POSSIBLY INTENSIFY BEFORE WIND SHEAR INCREASES... ALTHOUGH SO FAR BERTHA SHOWS NO SIGNS OF BECOMING A HURRICANE. THE INTENSITY FORECAST WILL REMAIN SIMILAR TO PREVIOUS... AND NOT TOO FAR FROM THE FSU SUPERENSEMBLE. THE GFS AND ECMWF ARE FORECASTING THE SYSTEM TO INTERACT WITH AN UPPER-LEVEL TROUGH STARTING IN ABOUT 96 HR...WHICH SHOULD CAUSE AN EXTRATROPICAL TRANSITION OF BERTHA AROUND DAY 5. BERTHA HAS SHOWN NO INDICATION OF THE FORECAST RIGHT TURN AND CONTINUES ON A TRACK OF ABOUT 030/8. HOWEVER THIS CHANGE IN DIRECTION SHOULD OCCUR SOON AS MIDDLE-LEVEL RIDGING IS BECOMING WEAKER ON WATER VAPOR IMAGES. AS THE RIDGE COLLAPSES...BERTHA SHOULD BE STEERED MORE TO THE EAST...THEN SOUTHEAST AND NORTHEAST IN AN ARCING SEMICIRCLE FASHION AROUND A LARGE DEEP-LAYERED LOW TO THE EAST. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT IN TRACK AND THE OFFICIAL FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ONE. BERTHA IS NOW THE LONGEST-LIVED JULY TROPICAL STORM IN ATLANTIC HISTORY...WITH 12.5 DAYS AS A TROPICAL STORM OR GREATER. THIS ECLIPSES THE PREVIOUS RECORD OF 12.25 DAYS OCCURRING IN 1916 FROM STORM #2. FORECAST POSITIONS AND MAX WINDS INITIAL 15/2100Z 36.4N 62.3W 60 KT 12HR VT 16/0600Z 36.8N 61.5W 60 KT 24HR VT 16/1800Z 36.3N 60.5W 65 KT 36HR VT 17/0600Z 35.1N 59.5W 60 KT 48HR VT 17/1800Z 34.2N 57.5W 55 KT 72HR VT 18/1800Z 35.7N 53.5W 50 KT 96HR VT 19/1800Z 39.5N 49.0W 45 KT 120HR VT 20/1800Z 43.5N 44.0W 45 KT...EXTRATROPICAL $$ FORECASTER BLAKE |
