Tropical Storm BERTHA

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TROPICAL STORM BERTHA DISCUSSION NUMBER  55
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
500 PM EDT WED JUL 16 2008

BERTHA REMAINS A POWERFUL SYSTEM WITH A LARGE WIND FIELD AND A
RAGGED EYE. THERE HAS BEEN LITTLE CHANGE TO THE SATELLITE
PRESENTATION FROM THIS MORNING SO THE INITIAL INTENSITY WILL REMAIN
60 KT.  LARGE-SCALE GUIDANCE SUGGESTS THAT THE ENVIRONMENT AROUND
THE STORM SHOULD BE FAVORABLE ENOUGH TO MAINTAIN THE TROPICAL
CYCLONE'S INTENSITY FOR A DAY OR SO.  THEREAFTER...A SLOW DECREASE
IN STRENGTH IS FORECAST AS SSTS DIMINISH SLOWLY ALONG THE TRACK.
THE EXTRATROPICAL TRANSITION OF BERTHA SHOULD START IN ABOUT 3-4
DAYS DUE TO THE EFFECTS OF A MIDDLE-LATITUDE TROUGH AND EVEN COOLER
WATERS. THE OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS
ONE...SHOWING ONLY A SLOW DEMISE OF THE STORM.

THE STORM HAS MADE THE SOUTHEASTWARD TURN AND IS NOW MOVING 140/4. A
LARGE MIDDLE- TO UPPER-LEVEL LOW TO THE EAST IS NOW STEERING BERTHA
AROUND ITS PERIPHERY. MODEL GUIDANCE REMAINS IN GOOD AGREEMENT
DURING THE FIRST FEW DAYS OF THE FORECAST TAKING THE STORM TO THE
SOUTHEAST...EAST...THEN NORTHEAST. HOWEVER... THERE IS SOME
DISAGREEMENT AS TO WHETHER BERTHA WILL BE SENT OUT TO SEA BY THE
UPPER LOW OR WHETHER A SECOND TROUGH WILL FINISH OFF THE STORM.
MOST OF THE GUIDANCE IS GOING WITH A FASTER SOLUTION...AND THE
OFFICIAL FORECAST LEANS IN THAT DIRECTION.  
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/2100Z 36.1N  60.5W    60 KT
 12HR VT     17/0600Z 35.5N  59.9W    60 KT
 24HR VT     17/1800Z 34.7N  58.1W    60 KT
 36HR VT     18/0600Z 35.1N  55.6W    55 KT
 48HR VT     18/1800Z 36.9N  53.1W    55 KT
 72HR VT     19/1800Z 41.5N  47.5W    50 KT
 96HR VT     20/1800Z 46.5N  41.0W    45 KT...EXTRATROPICAL
120HR VT     21/1800Z 52.5N  32.5W    45 KT...EXTRATROPICAL
 
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FORECASTER BLAKE
 
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