000 WTNT42 KNHC 092032 TCDAT2 HURRICANE BERTHA DISCUSSION NUMBER 27 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022008 500 PM EDT WED JUL 09 2008 BERTHA'S SATELLITE PRESENTATION HAS DRAMATICALLY IMPROVED DURING THE LAST 6 HOURS. THE CYCLONE NOW HAS A DISTINCTIVE EYE AND IS SURROUNDED BY A SYMMETRIC RING OF COLD CLOUD TOPS. THE INITIAL INTENSITY IS RAISED TO 90 KT BASED ON A BLEND OF THE SATELLITE CLASSIFICATIONS FROM SAB AND TAFB. BERTHA IS FORECAST TO BE IN A SEEMINGLY FAVORABLE ENVIRONMENT FOR THE NEXT DAY OR SO AND CONTINUED STRENGTHENING IS EXPECTED IN THE SHORT-TERM. BEYOND 36 HOURS...VERTICAL SHEAR IS STILL EXPECTED TO GRADUALLY INCREASE AND SSTS SLOWLY FALL. THIS ENVIRONMENT IS EXPECTED TO RESULT IN A SLOW WEAKENING TREND THROUGH THE END OF THE FORECAST PERIOD. IT SHOULD BE NOTED THAT BERTHA COULD BECOME A LITTLE STRONGER THAN CURRENTLY FORECAST IN THE FIRST 24 HOURS. BERTHA HAS RECENTLY WOBBLED A LITTLE RIGHT OF THE PREVIOUS MOTION ESTIMATE BUT THE 12 HOUR AVERAGE MOTION IS ESSENTIALLY UNCHANGED...305/10. THE TRACK FORECAST PHILOSOPHY IS THE SAME AS IN THE PREVIOUS ADVISORY. A MID-TROPOSPHERIC ANTICYCLONE CURRENTLY OVER THE WESTERN ATLANTIC IS FORECAST TO MOVE NORTHEASTWARD WHILE A SHORTWAVE TROUGH MOVES OFF OF THE U.S. EAST COAST. THIS SHOULD RESULT IN BERTHA MAKING A GRADUAL TURN TOWARD THE NORTH DURING THE NEXT 2-3 DAYS. HOWEVER...THIS TROUGH IS FORECAST TO BYPASS BERTHA TO THE NORTH AND LEAVE IT BEHIND IN RELATIVELY WEAK STEERING CURRENTS. ACCORDINGLY...THE OFFICIAL FORECAST SHOWS A SLOW NORTHWARD MOTION AT DAYS 3 AND 4. A SECOND TROUGH MOVING OFF THE UNITED STATES EAST COAST ON DAY 5 COULD RESULT IN SOME NORTHWARD ACCELERATION LATE IN THE FORECAST PERIOD. IN GENERAL...TRACK MODELS HAVE CHANGED LITTLE SINCE THE LAST ADVISORY...AND THE NEW OFFICIAL TRACK FORECAST IS ESSENTIALLY AN UPDATE OF THE PREVIOUS ONE. IT IS STILL TOO EARLY TO KNOW WHETHER BERTHA WILL HAVE AN IMPACT ON BERMUDA. INTERESTS ON THAT ISLAND SHOULD CONTINUE TO MONITOR THE PROGRESS OF THIS HURRICANE OVER THE NEXT COUPLE OF DAYS. FORECAST POSITIONS AND MAX WINDS INITIAL 09/2100Z 24.8N 58.1W 90 KT 12HR VT 10/0600Z 25.6N 59.2W 100 KT 24HR VT 10/1800Z 26.8N 60.2W 100 KT 36HR VT 11/0600Z 28.0N 61.0W 100 KT 48HR VT 11/1800Z 29.1N 61.3W 95 KT 72HR VT 12/1800Z 31.0N 61.5W 85 KT 96HR VT 13/1800Z 32.5N 61.0W 80 KT 120HR VT 14/1800Z 35.5N 60.0W 75 KT $$ FORECASTER RHOME