Tropical Depression FIVE

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TROPICAL DEPRESSION FIVE DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL052006
1100 PM EDT THU AUG 24 2006

LATEST INFRARED SATELLITE IMAGERY INDICATES THE TROPICAL CYCLONE HAS
MAINTAINED CONVECTION IN A SOMEWHAT SHEARED ENVIRONMENT. A BLEND OF
DVORAK CLASSIFICATIONS YIELDS A DATA T-NUMBER OF 2.0 OR 30 KT. BASED
UPON THIS INFORMATION AS WELL AS LITTLE CHANGE IN THE CONVECTIVE
ORGANIZATION...THE CYCLONE IS KEPT AS A TROPICAL DEPRESSION WITH 30
KT MAXIMUM WINDS. 

THE INITIAL MOTION IS 280/17...WHICH IS AN AVERAGE OF THE LAST SIX
HOURS.  THE CYCLONE IS CURRENTLY BEING STEERED ON A WESTERLY TRACK
BY A LOW- TO MID-LEVEL RIDGE STRETCHING ACROSS THE SOUTHWESTERN
ATLANTIC.  THE UKMET AND NOGAPS MODELS MAINTAIN THIS RIDGE TO THE
NORTH OF THE DEPRESSION AND TAKE A RELATIVELY WEAK SYSTEM ON A
STRAIGHT WESTWARD TRACK.  THE GFS AND GFDL MODELS FORECAST A
WEAKNESS IN THE RIDGE TO THE NORTH AND FORECAST A STRONGER CYCLONE
TO BE IN THE VICINITY OF WESTERN CUBA IN 5 DAYS.  THE OFFICIAL
TRACK FORECAST IS NUDGED SLIGHTLY TO THE NORTH OF THE PREVIOUS
ADVISORY...TOWARD THE GFS AND GFDL SOLUTIONS.
  
THE INTENSITY FORECAST IS HIGHLY CONTINGENT UPON A COMPLICATED
UPPER-LEVEL PATTERN FOR WHICH THE GLOBAL MODELS PROVIDE DIFFERING
SOLUTIONS. AN UPPER-LEVEL LOW OVER THE WESTERN CARIBBEAN IS
FORECAST TO SPLIT FROM A SHEAR AXIS CURRENTLY STRETCHED ALONG 25N
IN THE WESTERN ATLANTIC.  THE UKMET AND NOGAPS MODELS KEEP THE
UPPER-LEVEL LOW INTACT AND MOVE IT WESTWARD OVER THE NEXT 3 TO 5
DAYS TO THE SOUTH OF A LARGE MID-UPPER ANTICYCLONE OVER THE
SOUTHEASTERN UNITED STATES. THIS SCENARIO MIGHT KEEP SOME SOUTHERLY
SHEAR OVER THE TROPICAL CYCLONE.  ON THE OTHER HAND...THE GFS AND
GFDL MODELS MOVE THE UPPER-LEVEL LOW FASTER TO THE WEST...CREATING
A MUCH WEAKER SHEAR ENVIRONMENT OVER THE WESTERN CARIBBEAN AT DAYS
3 TO 5.  ALL THIS MEANS IS THAT THE INTENSITY FORECAST IS HIGHLY
UNCERTAIN.  BOTH THE SHIPS AND GFDL MODELS INTENSIFY THE CYCLONE TO
A HURRICANE WITHIN 3 DAYS.  THEREAFTER...THE GFDL MODEL WEAKENS THE
SYSTEM OVER CUBA BUT THE SHIPS FORECAST CONTINUED STRENGTHENING
THROUGH 5 DAYS. THE OFFICIAL INTENSITY FORECAST IS NUDGED UPWARD
TOWARD THE GFDL AND SHIPS GUIDANCE.

  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/0300Z 13.2N  63.9W    30 KT
 12HR VT     25/1200Z 13.7N  66.2W    35 KT
 24HR VT     26/0000Z 14.5N  68.9W    40 KT
 36HR VT     26/1200Z 15.3N  71.1W    45 KT
 48HR VT     27/0000Z 16.0N  73.0W    55 KT
 72HR VT     28/0000Z 17.5N  77.0W    65 KT
 96HR VT     29/0000Z 19.5N  81.0W    65 KT
120HR VT     30/0000Z 22.0N  85.0W    65 KT
 
$$
FORECASTER MAINELLI/KNABB
 
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