290 
 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
  
 
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