Tropical Storm CRISTOBAL

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TROPICAL STORM CRISTOBAL DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL032008
1100 AM EDT TUE JUL 22 2008
 
A 1013 SSMIS MICROWAVE PASS SHOWED A BANDED EYE STRUCTURE WITH
CRISTOBAL...THOUGH IT ALSO INDICATED THE SURFACE CENTER WAS ON THE
NORTHWESTERN EDGE OF THE DEEP CONVECTION. BUOY 44011 ALSO SUGGESTS
THE SURFACE CIRCULATION IS ELONGATED FROM SOUTHEAST TO NORTHWEST.
HOWEVER...BECAUSE OF THE IMPROVING SATELLITE PRESENTATION...THE
WINDS ARE INCREASED CONSERVATIVELY TO 55 KT. THIS SHOULD BE THE
LAST HURRAH FOR CRISTOBAL AS THE CYCLONE HAS PASSED NORTH OF THE
GULF STREAM INTO COOLER WATERS. A RAPID EXTRATROPICAL TRANSITION IS
FORECAST BY ALL MODELS AND IS INDICATED BELOW. STEADY WEAKENING AS
AN EXTRATROPICAL CYCLONE IS FORECAST DUE TO A STRONG SHEARING
ENVIRONMENT AND NO BAROCLINIC FORCING.
 
CRISTOBAL IS REALLY START TO MOVE AND THE INITIAL MOTION ESTIMATE IS
050/22.  THERE IS NO CHANGE TO THE SYNOPTIC REASONING FROM THE
PREVIOUS FORECAST.  THE CYCLONE IS EXPECTED TO MOVE TOWARD THE
NORTHEAST TODAY AND THEN EAST TOMORROW AS IT ROUNDS THE NORTHERN
PORTION OF THE SUBTROPICAL RIDGE IN THE CENTRAL ATLANTIC.  A TURN
TOWARD THE SOUTHEAST IS FORECAST DUE TO AN APPROACHING
MIDDLE-LATITUDE TROUGH AND THE SYSTEM SHOULD EITHER DISSIPATE
AROUND 4 DAYS OR BE ABSORBED BY A FRONTAL BOUNDARY.  THE OFFICIAL
FORECAST IS BASICALLY AN UPDATE TO THE PREVIOUS ONE AND IS SLIGHTLY
SOUTH OF AND FASTER THAN THE DYNAMICAL MODEL CONSENSUS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/1500Z 40.9N  65.9W    55 KT
 12HR VT     23/0000Z 42.9N  62.6W    50 KT...BECOMING EXTRATROPICAL
 24HR VT     23/1200Z 44.5N  57.0W    40 KT...EXTRATROPICAL
 36HR VT     24/0000Z 44.0N  51.5W    35 KT...EXTRATROPICAL
 48HR VT     24/1200Z 42.5N  46.5W    30 KT...EXTRATROPICAL
 72HR VT     25/1200Z 39.0N  41.5W    25 KT...EXTRATROPICAL
 96HR VT     26/1200Z...DISSIPATED
 
$$
FORECASTER BLAKE
 
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