000
WTNT44 KNHC 142053
TCDAT4
TROPICAL STORM DEAN DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT TUE AUG 14 2007
 
DEAN'S STRUCTURE HAS NOT IMPROVED DURING THE AFTERNOON. CONVECTION
HAS WANED AND REMAINS ESPECIALLY LIMITED IN THE NORTHEASTERN
SEMICIRCLE...THOUGH THIS MAY BE A DIURNAL FLUCTUATION. BOTH TAFB
AND SAB GAVE DVORAK ESTIMATES OF T2.5 OR 35 KT...WHILE AN AMSU PASS
AT 1623 UTC SUGGESTED A SUBSTANTIALLY STRONGER INTENSITY. GIVEN THE
LACK OF CONVECTIVE VIGOR...THE INTENSITY OF DEAN IS KEPT AT 35 KT.

INITIAL MOTION OF DEAN IS 265 DEGREES AT 18 KT...A BIT SLOWER THAN
THE LAST ADVISORY.  DEAN IS SOUTH OF A DEEP-LAYERED RIDGE WHICH
SHOULD STEER THE CYCLONE TOWARD THE WEST OR WEST-NORTHWEST FOR THE
NEXT FEW DAYS.  THE MODEL GUIDANCE SHIFTED SOMEWHAT TO THE WEST AND
FASTER COMPARED TO THE 06 UTC RUNS...PERHAPS DUE TO A WEAKER AND
LESS DIGGING TROUGH OFF OF THE U.S. EAST COAST BY DAY 5.  THE
OFFICIAL TRACK FORECAST IS TO THE LEFT OF AND FASTER THAN THE
PREVIOUS ADVISORY...BUT REMAINS TO THE RIGHT OF THE CONSENSUS OF
THE GFS...GFDL...AND HWRF.  COMPARED TO THE OTHER MODELS...TRACK
SOLUTIONS FOR THE NOGAPS AND ECMWF ARE SLOWER BECAUSE THEY DO NOT
APPEAR TO HAVE A GOOD HANDLE ON DEAN'S FAST INITIAL FORWARD SPEED.

DEAN IS CURRENTLY EXPERIENCING MODERATE NORTHEASTERLY SHEAR...IS
OVER 27.5C SSTS...AND IS WITHIN A MOIST ENVIRONMENT.  THE SHEAR
SHOULD DROP WHILE THE SSTS WARM OVER THE NEXT FEW DAYS...SO THE
ENVIRONMENT APPEARS TO BE CONDUCIVE FOR GRADUAL INTENSIFICATION. 
THE INTENSITY FORECAST IS CLOSE A CONSENSUS OF THE HWRF...
GFDL...SHIPS...AND LGEM THROUGH 72 HR.  THEREAFTER...THE INTENSITY
FORECAST RELIES PRIMARILY UPON THE GFDL AND LGEM MODELS.  BY DAY
5...DEAN IS FORECAST TO BE A STRENGTHENING HURRICANE AND COULD
REACH MAJOR HURRICANE STATUS BY THEN.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/2100Z 11.6N  41.0W    35 KT
 12HR VT     15/0600Z 11.7N  43.6W    40 KT
 24HR VT     15/1800Z 12.0N  46.9W    45 KT
 36HR VT     16/0600Z 12.3N  50.2W    50 KT
 48HR VT     16/1800Z 12.6N  53.5W    60 KT
 72HR VT     17/1800Z 14.0N  59.5W    70 KT
 96HR VT     18/1800Z 15.5N  64.5W    85 KT
120HR VT     19/1800Z 17.5N  69.5W    95 KT
 
$$
FORECASTER LANDSEA/KNABB