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| #201978 (Received by flhurricane at: 5:08 AM 20.Jul.2008) TCDAT2 TROPICAL STORM BERTHA DISCUSSION NUMBER 69 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 500 AM EDT SUN JUL 20 2008 ALTHOUGH THE CONVECTION IS NOT VERY DEEP...THE CLOUD PATTERN OF BERTHA STILL LOOKS SOMEWHAT SYMMETRIC...I.E. TROPICAL...AND A SHIP WITH CALL SIGN WDC6925 REPORTED 44 KT WINDS NOT FAR FROM THE CENTER...WHICH IS ALSO INDICATIVE OF A TROPICAL STRUCTURE. PHASE SPACE ANALYSES FROM FLORIDA STATE UNIVERSITY USING THE GFS FORECAST FIELDS INDICATE THAT BERTHA WILL BECOME AN EXTRATROPICAL CYCLONE VERY SOON...PROBABLY NOT LONG AFTER 1200 UTC TODAY. THE FORECAST SHOWS BERTHA'S EXTRATROPICAL REMNANT BECOMING ABSORBED BY 72 HOURS BUT GLOBAL MODELS FORECASTS SUGGEST THAT THIS EVENT COULD OCCUR SOONER. FOR NEXT DAY OR TWO...HOWEVER...THE POST-BERTHA CYCLONE SHOULD REMAIN A FAIRLY POWERFUL EXTRATROPICAL STORM. BERTHA IS ACCELERATING AND THE INITIAL MOTION IS NOW AROUND 035/26. AN ADDITIONAL INCREASE IN FORWARD SPEED IS EXPECTED AS THE CYCLONE MOVES WITH THE FLOW ON THE SOUTHEAST SIDE OF A BROAD MID-LATITUDE TROUGH...UNTIL THE SYSTEM MERGES WITH OR IS ABSORBED BY ANOTHER LOW. THE TRACK FORECAST IS IN GOOD AGREEMENT WITH THE MODEL CONSENSUS AND SIMILAR TO THAT FROM THE PREVIOUS ADVISORY. FORECAST POSITIONS AND MAX WINDS INITIAL 20/0900Z 48.5N 38.9W 60 KT 12HR VT 20/1800Z 52.5N 34.5W 55 KT...EXTRATROPICAL 24HR VT 21/0600Z 58.0N 28.0W 55 KT...EXTRATROPICAL 36HR VT 21/1800Z 63.0N 21.0W 50 KT...EXTRATROPICAL 48HR VT 22/0600Z 67.0N 15.0W 50 KT...EXTRATROPICAL 72HR VT 23/0600Z...ABSORBED $$ FORECASTER PASCH |
