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| #201458 (Received by flhurricane at: 10:55 AM 17.Jul.2008) TCDAT2 TROPICAL STORM BERTHA DISCUSSION NUMBER 58 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 1100 AM EDT THU JUL 17 2008 A QUIKSCAT PASS AT 0912 UTC SUGGESTED THAT THE MAXIMUM WINDS OF BERTHA WERE ABOUT 50 KT AT THAT TIME. SINCE THEN...NEW THUNDERSTORMS HAVE DEVELOPED IN THE EASTERN SEMICIRCLE OF THE STORM. ALTHOUGH SATELLITE CLASSIFICATIONS ARE DECREASING...I'M HESITANT TO LOWER THE WINDS TOO MUCH BASED ON THE QUIKSCAT DATA AND THE RESILENCY OF THE SYSTEM. 50 KT WILL BE USED AS THE INITIAL INTENSITY. LITTLE CHANGE IN STRENGTH IS FORECAST FOR THE NEXT DAY OR SO IN AGREEMENT WITH MOST GUIDANCE. HOWEVER...IT IS TEMPTING TO LOWER THE WINDS A LITTLE MORE BEFORE EXTRATROPICAL TRANSITION OCCURS. THE OFFICIAL FORECAST IS VERY SIMILAR TO THE PREVIOUS FORECAST AND IS BELOW MOST OF THE INTENSITY GUIDANCE. BERTHA MAY BECOME A LARGE POWERFUL EXTRATROPICAL LOW IN THE HIGH LATITUDES OF THE NORTH ATLANTIC BY DAY 5. THE STORM APPEARS TO HAVE TURNED TOWARD THE EAST-SOUTHEAST AT ABOUT 8 KT. THE CYCLONE SHOULD BEGIN ITS MOTION TOWARD THE NORTHEAST BY TOMORROW AS IT IS STEERED AROUND A MIDDLE- TO UPPER-LEVEL LOW TO THE NORTH. MODEL GUIDANCE IS IN GOOD AGREEMENT ON THE TRACK AND LITTLE CHANGE IS MADE TO THE OFFICIAL FORECAST. THEREAFTER THE BIGGEST QUESTION IS WHETHER A NEW MIDDLE-LATITUDE TROUGH WILL CAPTURE BERTHA...LIKE THE UKMET/ECMWF SHOWS...OR THE STORM WILL REMAIN A MORE SEPARATE ENTITY LIKE THE GFS/GFDL/HWRF SOLUTIONS. THE OFFICAL FORECAST LEANS ON THE WESTERN SIDE OF THE GUIDANCE...SHOWING A LITTLE MORE TROUGH INTERACTION. BERTHA COULD BECOME ONE OF THE TOP 10 LONGEST-LIVED STORMS IN HISTORY IF IT SURVIVES UNTIL THE WEEKEND. FORECAST POSITIONS AND MAX WINDS INITIAL 17/1500Z 34.2N 58.4W 50 KT 12HR VT 18/0000Z 34.1N 56.9W 45 KT 24HR VT 18/1200Z 35.2N 54.5W 45 KT 36HR VT 19/0000Z 37.3N 51.8W 45 KT 48HR VT 19/1200Z 39.3N 49.1W 45 KT 72HR VT 20/1200Z 43.5N 43.0W 45 KT...BECOMING EXTRATROPICAL 96HR VT 21/1200Z 51.0N 34.0W 50 KT...EXTRATROPICAL 120HR VT 22/1200Z 57.5N 22.0W 50 KT...EXTRATROPICAL $$ FORECASTER BLAKE |
