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Tropical Storm BERTHA (Text)

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TROPICAL STORM BERTHA DISCUSSION NUMBER  59
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022008
500 PM EDT THU JUL 17 2008
 
SATELLITE IMAGES INDICATE THAT BERTHA IS MAINTAINING ITS STRUCTURE
AS A TROPICAL STORM WITH DEFINED BANDING FEATURES AND OUTFLOW
ALOFT.  CONVECTION HAS BEEN WELL-MAINTAINED...ESPECIALLY IN THE
NORTHEAST QUADRANT OF THE STORM.  THERE HAS BEEN NO CHANGE IN THE
SATELLITE CLASSIFICATIONS SO THE INITIAL INTENSITY WILL REMAIN 50
KT.  NO SIGNIFICANT INTENSITY FLUCTUATIONS ARE EXPECTED DURING THE
NEXT DAY OR SO AS THE STORM REMAINS UNDER THE INFLUENCE OF MODERATE
SHEAR AND WANING SSTS.  THE EXTRATROPICAL TRANSITION PROCESS SHOULD
START SHORTLY AFTER 48 HR DUE TO AN INCREASE IN SHEAR AND MORE
RAPIDLY DECREASING SSTS...AND BY 120 HR...THE REMNANTS OF BERTHA
WILL LIKELY BE ABSORBED INTO A LARGER EXTRATROPICAL LOW.

THE STORM HAS MADE AN EASTWARD TURN AND IS MOVING ABOUT 090/10.  A
BUILDING RIDGE TO THE EAST OF BERTHA SHOULD STEER THE STORM MORE TO
THE NORTHEAST TOMORROW...FOLLOWING CLOSE BEHIND A MIDDLE- TO
UPPER-LEVEL LOW TO ITS NORTH.  MODEL GUIDANCE IS TIGHTLY CLUSTERED
ON AN ACCELERATING PATH OUT TO SEA.  THE GFS HAS CHANGED FROM THE
SOUTH TO NORTH SIDE OF THE MODEL CONSENSUS...NOW SHOWING MORE
INTERACTION WITH A NEW MIDDLE-LATITUDE TROUGH IN A COUPLE OF DAYS. 
THE OFFICIAL FORECAST LIES ON THE LEFT SIDE OF THE CONSENSUS AND IS
PRETTY CLOSE TO THE PREVIOUS ONE.  
 
TO CLARIFY A PREVIOUS DISCUSSION COMMENT...BERTHA COULD BECOME ONE
OF THE TOP 10 LONGEST-LIVED ATLANTIC STORMS...IN TERMS OF DAYS AS A
TROPICAL STORM OR GREATER...IF IT SURVIVES UNTIL SUNDAY.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/2100Z 34.0N  57.2W    50 KT
 12HR VT     18/0600Z 34.4N  55.6W    45 KT
 24HR VT     18/1800Z 35.9N  53.3W    45 KT
 36HR VT     19/0600Z 37.8N  51.0W    45 KT
 48HR VT     19/1800Z 39.9N  48.3W    45 KT
 72HR VT     20/1800Z 45.0N  41.0W    50 KT...EXTRATROPICAL
 96HR VT     21/1800Z 53.5N  30.0W    50 KT...EXTRATROPICAL
120HR VT     22/1800Z...ABSORBED
 
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FORECASTER BLAKE
 
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