Tropical Depression FOUR

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TROPICAL DEPRESSION FOUR DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT MON AUG 13 2007
 
THE ORGANIZATION OF THE DEPRESSION HAS CERTAINLY NOT IMPROVED THIS
EVENING.  THE OVERALL CONVECTIVE ENVELOPE APPEARS TO HAVE BECOME
ELONGATED EAST TO WEST AS THE DEPRESSION CONTINUES TO BE PLAGUED BY
STRONG UPPER-LEVEL EASTERLY WINDS.  A QUIKSCAT PASS DURING THE
AFTERNOON CAUGHT THE EASTERN PORTION OF THE CIRCULATION AND IT
SUGGESTS THAT THE MAXIMUM WINDS REMAIN NEAR 30 KT. THE LATEST
DVORAK SATELLITE INTENSITY ESTIMATE ALSO SUPPORT 30 KT AND THE
CYCLONE WILL REMAIN A DEPRESSION FOR THIS ADVISORY.

THE DEPRESSION CONTINUES TO MOVE BRISKLY WESTWARD...WITH AN INITIAL
MOTION ESTIMATE OF 270/17.  THE CYCLONE IS EXPECTED TO CONTINUE
MOVING WESTWARD DURING THE NEXT COUPLE OF DAYS...SOUTH OF A DEEP
LAYER RIDGE.  THE OFFICIAL FORECAST CONTINUES TO BE FASTER THAN
VIRTUALLY ALL OF THE GUIDANCE DURING THAT TIME PERIOD. 
THEREAFTER...MOST OF THE MODELS INDICATE THAT THE SUBTROPICAL RIDGE
WILL WEAKEN OVER THE CENTRAL ATLANTIC...ALLOWING THE CYCLONE TO
TURN WEST-NORTHWESTWARD.  THE GFDL AND HWRF REMAIN ON THE RIGHT
SIDE OF THE GUIDANCE ENVELOPE...SHOWING AN EARLIER TURN TOWARD THE
WEST-NORTHWEST.  THE NEW OFFICIAL TRACK IS CLOSE TO THE GFS AND
UKMET SOLUTIONS AND IS VERY CLOSE TO THE PREVIOUS NHC TRACK.
 
THE INTENSITY FORECAST PHILOSOPHY REMAINS UNCHANGED FROM THE
PREVIOUS ADVISORY.  MOST OF THE GUIDANCE SUGGESTS THAT THE SHEAR
WILL DECREASE DURING THE NEXT COUPLE OF DAYS ALLOWING THE CYCLONE TO
GRADUALLY STRENGTHEN.  THE EXPLICIT INTENSITY GUIDANCE IS IN
REMARKABLY GOOD AGREEMENT AND THE OFFICIAL FORECAST IS UNCHANGED
FROM THE PREVIOUS ADVISORY.  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/0300Z 12.0N  35.0W    30 KT
 12HR VT     14/1200Z 12.0N  37.4W    35 KT
 24HR VT     15/0000Z 12.0N  40.4W    40 KT
 36HR VT     15/1200Z 12.2N  43.4W    45 KT
 48HR VT     16/0000Z 12.6N  46.4W    50 KT
 72HR VT     17/0000Z 13.8N  52.0W    60 KT
 96HR VT     18/0000Z 16.0N  57.5W    75 KT
120HR VT     19/0000Z 18.5N  62.5W    90 KT
 
$$
FORECASTER BROWN/FRANKLIN
 
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