Tropical Depression FOUR

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TROPICAL DEPRESSION FOUR DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042010
1100 PM EDT MON AUG 02 2010
 
THERE HAS BEEN LITTLE CHANGE TO THE ORGANIZATION OF THE DEPRESSION
THIS EVENING.  VERY LITTLE BANDING FEATURES ARE SEEN AND THE
CENTER IS NEAR THE EASTERN EDGE OF A SMALL AREA OF DEEP
CONVECTION.  THE INITIAL INTENSITY WILL REMAIN 30 KT...BASED ON
DVORAK CLASSIFICATIONS OF T2.0 FROM SAB AND TAFB.  NOAA BUOY 41041
HAS RECENTLY REPORTED A PEAK 1-MINUTE SUSTAINED WIND OF 25 KT ABOUT
70 N MI NORTHWEST OF THE CENTER.
 
A SERIES OF MICROWAVE IMAGES THIS EVENING WERE HELPFUL IN LOCATING
THE CENTER OF THE DEPRESSION.  THE CYCLONE HAS ACCELERATED DURING
THE PAST 6-12 HOURS...WITH AN INITIAL MOTION OF 285/20.  THE TRACK
GUIDANCE IS IN RELATIVELY GOOD AGREEMENT THROUGH 48 HOURS.  DURING
THIS TIME THE DEPRESSION IS EXPECTED TO CONTINUE ON A
WEST-NORTHWESTWARD HEADING TO THE SOUTH OF A MID-LEVEL RIDGE OVER
THE CENTRAL ATLANTIC.  BEYOND 48 HOURS...THE CYCLONE WILL BE
APPROACHING A BREAK IN THE RIDGE OVER THE WESTERN ATLANTIC...WHICH
SHOULD ALLOW THE DEPRESSION TO TURN MORE NORTHWESTWARD. THE TRACK
GUIDANCE IN THE LONGER RANGE IS IN POOR AGREEMENT.  THE GFDL AND
HWRF MODELS TURN THE CYCLONE NORTHWARD MUCH EARLIER...WHILE THE GFS
MAINTAINS A MORE WEST-NORTHWESTWARD MOTION AND LIES ALONG THE
WESTERN EDGE OF THE GUIDANCE ENVELOPE.  ALTHOUGH THE TVCN CONSENSUS
SHIFTED CONSIDERABLY EASTWARD THIS CYCLE...WE PREFER TO KEEP THE
TRACK ON THE LEFT SIDE OF THE GUIDANCE SINCE THE SYSTEM IS EXPECTED
TO BE WEAK AT THAT TIME.
 
THE DEPRESSION IS FORECAST TO BE IN A FAVORABLE UPPER-LEVEL
ENVIRONMENT DURING THE NEXT DAY OR SO AND THE OFFICIAL FORECAST
WILL CONTINUE TO CALL FOR SLOW STRENGTHENING.  IN 36-48 HOURS...
SOUTHWESTERLY SHEAR IS FORECAST TO INCREASE AS THE CYCLONE
APPROACHES AN UPPER-LEVEL TROUGH OVER THE WESTERN ATLANTIC.  THIS
IS EXPECTED TO HALT ANY ADDITIONAL STRENGTHENING.  THE NEW FORECAST
IS A LITTLE BELOW THE PREVIOUS ADVISORY AND IS IN GOOD AGREEMENT
WITH THE LGEM AND GFDL MODELS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      03/0300Z 13.6N  45.1W    30 KT
 12HR VT     03/1200Z 14.6N  48.1W    35 KT
 24HR VT     04/0000Z 16.0N  52.2W    40 KT
 36HR VT     04/1200Z 17.7N  56.4W    45 KT
 48HR VT     05/0000Z 19.6N  59.9W    50 KT
 72HR VT     06/0000Z 23.5N  65.5W    45 KT
 96HR VT     07/0000Z 27.0N  68.5W    45 KT
120HR VT     08/0000Z 31.0N  69.5W    45 KT
 
$$
FORECASTER BROWN
 
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