Tropical Storm BERTHA

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TROPICAL STORM BERTHA DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
500 PM EDT FRI JUL 04 2008
 
BERTHA HAD A RATHER RAGGED APPEARANCE IN SATELLITE IMAGERY AROUND
MID-DAY...HOWEVER...SINCE THEN A NEW BURST OF CONVECTION WITH VERY
COLD CLOUD TOPS HAS DEVELOPED NEAR AND NORTH OF THE CENTER.  DVORAK
INTENSITY ESTIMATES FROM TAFB AND SAB STILL SUPPORT AN INITIAL
INTENSITY OF 45 KT.  LITTLE CHANGE IN INTENSITY IS EXPECTED DURING
THE NEXT 24 HOURS AS BERTHA TRAVERSES OVER COOLER WATERS. 
THEREAFTER...THE SSTS WILL INCREASE ALONG THE PROJECTED
TRACK...HOWEVER...VERTICAL SHEAR IS FORECAST TO INCREASE IN THE 3-5
DAY TIME PERIOD.  THE NEW INTENSITY FORECAST IS UNCHANGED FROM THE
PREVIOUS ADVISORY AND KEEPS BERTHA'S INTENSITY BELOW HURRICANE
STRENGTH.  THE GFDL CONTINUES TO SHOW BERTHA REACHING HURRICANE
STATUS...BUT THE SHIPS MODEL HAS BACKED OFF A LITTLE...AND IS IN
LINE WITH THE OFFICIAL FORECAST.
 
BERTHA CONTINUES TO ACCELERATE AND IS NOW MOVING WEST-NORTHWESTWARD
OR 290/16.  LITTLE CHANGE IN HEADING IS EXPECTED DURING THE NEXT
2-3 DAYS AS THE STORM REMAINS SOUTH OF A MID-TROPOSPHERIC RIDGE.
THE GFDL TRACK HAS NOW SHIFTED WESTWARD AND HAS JOINED THE REMAINDER
OF THE MODEL GUIDANCE...EXCEPT FOR THE HWRF WHICH STILL INSISTS ON A
NORTHWESTWARD TURN.  THE NEW TRACK FORECAST REMAINS VERY SIMILAR TO
THE PREVIOUS ADVISORY THROUGH 48 HOURS BUT HAS SHIFTED FARTHER
SOUTHWESTWARD AT DAYS 3-5... IN GOOD AGREEMENT WITH THE LATEST
MODEL CONSENSUS AND THE ECMWF.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      04/2100Z 15.5N  31.6W    45 KT
 12HR VT     05/0600Z 16.2N  34.2W    45 KT
 24HR VT     05/1800Z 16.8N  37.8W    45 KT
 36HR VT     06/0600Z 17.4N  41.5W    50 KT
 48HR VT     06/1800Z 17.9N  45.2W    55 KT
 72HR VT     07/1800Z 19.2N  51.5W    60 KT
 96HR VT     08/1800Z 21.5N  56.0W    60 KT
120HR VT     09/1800Z 23.5N  60.5W    60 KT
 
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FORECASTER BROWN
 
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