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| #201146 (Received by flhurricane at: 11:08 AM 15.Jul.2008) TCDAT2 TROPICAL STORM BERTHA DISCUSSION NUMBER 50 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 1100 AM EDT TUE JUL 15 2008 BERTHA IS MAINTAINING ITS STRUCTURE ON SATELLITE IMAGES THIS MORNING WITH A NEW BURST OF CONVECTION ON THE NORTHEAST SIDE OF THE STORM... AND APPARENT EYEWALL MESOVORTICES ROTATING QUICKLY AROUND THE CENTER. HIGH-RESOLUTION QUIKSCAT SHOWS WINDS OF 55-60 KT...SO THE INITIAL INTENSITY WILL REMAIN 60 KT FOR THIS ADVISORY. THE STORM STILL HAS A CHANCE TO BECOME A HURRICANE AGAIN DURING THE NEXT DAY OR SO BEFORE VERTICAL WIND SHEAR INCREASES AS INDICATED BY ALL MODELS. THE STATISTICAL MODELS SUGGEST NO INTENSIFICATION BUT THE DYNAMICAL MODELS SUCH AS THE GFDL/HWRF EMPHATICALLY SUGGEST BERTHA WILL BECOME...AND MAINTAIN HURRICANE STRENGTH THROUGHOUT THE FORECAST PERIOD. THE INTENSITY FORECAST WILL BE CLOSER TO THE STATISTICAL GUIDANCE AT THIS TIME AS THE UPPER ENVIRONMENT DOES NOT SEEM TO BE TOO FAVORABLE FOR A HURRICANE BEYOND A COUPLE OF DAYS. THE STORM IS CURRENTLY MOVING 030/10...A LITTLE FASTER THAN BEFORE. A NARROW RIDGE TO THE EAST OF BERTHA IS STEERING THE CYCLONE NORTHEASTWARD FOR THE TIME BEING. THIS RIDGE IS FORECAST TO BE ERODED BY ALL THE GLOBAL MODELS WITHIN 24 HOURS AS A LARGE DEEP-LAYERED TROUGH APPROACHES FROM THE EAST. THE BIGGEST DISCREPANCY IS WHEN THE EXPECTED RIGHT TURN OF THE CYCLONE EMERGES. THE ECMWF/UKMET SHOW THAT THE TURN WILL BE DELAYED FOR AN EXTRA 12 HOURS...ALLOWING THE STORM TO GAIN MORE LATITUDE AS COMPARED TO THE GFS/GFDL/HWRF. THE OFFICIAL FORECAST WILL SPLIT THE DIFFERENCE BETWEEN THESE TWO MODEL CAMPS...AND SHIFTS THE TRACK NORTHWARD IN THE SHORT-TERM. UNCERTAINTY ALSO REMAINS HIGH IN THE LONG-RANGE FORECAST AS THE GFDL/HWRF ARE STILL SHOWING BERTHA SHOOTING OUT TO SEA WHILE THE GFS/ECMWF/UKMET ARE MUCH SLOWER. BECAUSE THE STORM IS NOT EXPECTED TO HAVE SUCH A WELL-DEVELOPED STRUCTURE LIKE THE FORMER MODELS ARE INDICATING...THE OFFICIAL FORECAST WILL LEAN MORE HEAVILY ON THE LARGE-SCALE MODELS THAT DELAY THE TROPICAL CYCLONE'S EVENTUAL DEMISE. AROUND 120 HOURS A COMBINATION OF COOLER WATERS AND AN UPPER-LEVEL TROUGH INTERACTION MAY...HOPEFULLY...START TO SIGNAL THE DEMISE OF BERTHA AS A TROPICAL CYCLONE. FORECAST POSITIONS AND MAX WINDS INITIAL 15/1500Z 35.6N 62.7W 60 KT 12HR VT 16/0000Z 36.4N 61.8W 65 KT 24HR VT 16/1200Z 36.2N 60.7W 65 KT 36HR VT 17/0000Z 35.1N 59.6W 65 KT 48HR VT 17/1200Z 34.1N 58.2W 60 KT 72HR VT 18/1200Z 34.5N 54.5W 55 KT 96HR VT 19/1200Z 37.5N 50.0W 50 KT 120HR VT 20/1200Z 41.5N 46.0W 45 KT...BECOMING EXTRATROPICAL $$ FORECASTER BLAKE |
