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| #199449 (Received by flhurricane at: 10:52 AM 06.Jul.2008) TCDAT2 TROPICAL STORM BERTHA DISCUSSION NUMBER 14 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 1100 AM EDT SUN JUL 06 2008 A SERIES OF MICROWAVE OVERPASSES THIS MORNING SHOW THAT BERTHA HAS CHANGED LITTLE IN ORGANIZATION DURING THE PAST 24 HOURS. QUIKSCAT DATA FROM 0852 UTC INDICATE THAT THE MAXIMUM WINDS REMAIN ABOUT 45 KT...WHICH AGREES WITH THE LATEST DVORAK INTENSITY ESTIMATES. HOWEVER...RECENT VISIBLE SATELLITE IMAGES REVEAL AN INCREASE IN CONVECTION WHICH MAY FORETELL AN INCREASE IN STRENGTH. SSTS UNDER BERTHA HAVE INCREASED TO AROUND 26 CELSIUS AND ARE EXPECTED TO WARM A COUPLE OF DEGREES DURING THE NEXT 2 DAYS. SHEAR IS FORECAST TO REMAIN LOW...SO GRADUAL STRENGTHENING IS EXPECTED DURING THE NEXT 48 HOURS AND BERTHA COULD BECOME A HURRICANE DURING THAT TIME. LATER IN THE FORECAST PERIOD...IT IS DIFFICULT TO DETERMINE EXACTLY WHAT EFFECT AN UPPER-LEVEL TROUGH OVER THE WESTERN ATLANTIC WILL HAVE ON THE CYCLONE. IF IT REMAINS IN PLACE...THE TROUGH WOULD PRODUCE AN INCREASE IN SOUTHWESTERLY SHEAR. SOME OF THE GLOBAL MODELS SUGGEST A WEAKENING OF THE TROUGH HOWEVER...WHICH WOULD KEEP BERTHA IN A MORE FAVORABLE ENVIRONMENT. DUE TO THESE UNCERTAINTIES THE INTENSITY FORECAST BEYOND 3 DAYS KEEPS BERTHA AT THE SAME STRENGTH. BERTHA CONTINUES MOVING RAPIDLY WESTWARD OR 280/18 KT. A WEST-NORTHWESTWARD TRACK WITH A REDUCTION IS FORWARD SPEED IS EXPECTED DURING THE NEXT DAY OR TWO. THERE IS A LITTLE LESS SPREAD IN THE MODELS THIS MORNING...WITH THE MAJORITY OF THE GUIDANCE SHOWING A MORE NORTHWESTWARD TURN IN 2-3 DAYS AS THE RIDGE OVER THE WESTERN ATLANTIC BEGIN TO WEAKEN. THE HWRF CONTINUES TO INSIST ON THE TURN OCCURRING MUCH SOONER...WHILE THE UKMET REMAINS THE WESTERNMOST MODEL BUT WITH A WEAKENED TROPICAL CYCLONE OR EVEN AN OPEN WAVE. THE OFFICIAL TRACK HAS BEEN ADJUSTED EASTWARD...BUT IT REMAINS LEFT OF MOST OF THE GUIDANCE AND ALSO LEFT OF THE MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INITIAL 06/1500Z 17.4N 45.1W 45 KT 12HR VT 07/0000Z 18.0N 47.8W 50 KT 24HR VT 07/1200Z 18.9N 50.9W 55 KT 36HR VT 08/0000Z 19.7N 53.5W 60 KT 48HR VT 08/1200Z 20.5N 56.0W 65 KT 72HR VT 09/1200Z 22.5N 60.5W 70 KT 96HR VT 10/1200Z 25.0N 64.0W 70 KT 120HR VT 11/1200Z 27.0N 66.5W 70 KT $$ FORECASTER BROWN |
