000
WTNT44 KNHC 020845
TCDAT4
TROPICAL STORM GASTON DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL092010
500 AM AST THU SEP 02 2010

SATELLITE IMAGES INDICATE THAT GASTON HAS GENERALLY CHANGED LITTLE
IN ORGANIZATION THIS MORNING. THUNDERSTORM ACTIVITY REMAINS CONFINED
TO A CURVED BAND OVER THE WESTERN SEMICIRCLE...BUT THE CLOUD TOPS
HAVE BEEN WARMING SLIGHTLY DURING THE LAST COUPLE OF HOURS. DVORAK
DATA T-NUMBERS ARE 35 KT FROM BOTH TAFB AND SAB...AND THE INITIAL
INTENSITY IS HELD AT THAT VALUE.  CONDITIONS GENERALLY APPEAR
FAVORABLE FOR A GRADUAL INTENSIFICATION DURING THE NEXT SEVERAL
DAYS AS GASTON REMAINS IN A LOW WIND SHEAR ENVIRONMENT AND OVER
WARM WATERS. HOWEVER...WATER VAPOR IMAGERY SHOWS THAT GASTON IS
PARTIALLY EMBEDDED IN A DRY MID- TO UPPER-LEVEL AIR MASS WHICH COULD
PROVE TO BE A LIMITING FACTOR.  GIVEN THE UNCERTAINTY...THE
OFFICIAL INTENSITY FORECAST IS UNCHANGED FROM EARLIER...LYING IN
BETWEEN THE DYNAMICAL MODEL GUIDANCE AND THE MORE AGGRESSIVE
STATISTICAL MODEL OUTPUT.
  
GASTON CONTINUES TO DECELERATE AS IT FEELS THE EFFECTS OF A DEEP
LAYER TROUGH TO ITS NORTH...AND THE INITIAL MOTION ESTIMATE IS NOW
280/8. GASTON IS FORECAST TO SLOW DOWN EVEN MORE OVER THE NEXT
COUPLE OF DAYS AS THE STORM REMAINS IN WEAK STEERING CURRENTS. BY
48-72 HOURS...GLOBAL MODELS SHOW SOME MID-LEVEL RIDGING BUILDING TO
THE NORTH OF GASTON AND THAT SHOULD STEER THE SYSTEM WESTWARD OR
EVEN WEST-SOUTHWESTWARD AT A SLIGHTLY FASTER SPEED. THE OFFICIAL
TRACK FORECAST IS A LITTLE SLOWER AND SLIGHTLY TO THE SOUTH OF THE
PREVIOUS ONE IN BEST AGREEMENT WITH THE MULTI-MODEL CONSENSUS.
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      02/0900Z 13.5N  38.2W    35 KT
 12HR VT     02/1800Z 13.6N  39.0W    40 KT
 24HR VT     03/0600Z 13.8N  40.1W    45 KT
 36HR VT     03/1800Z 14.0N  41.2W    50 KT
 48HR VT     04/0600Z 14.2N  42.5W    55 KT
 72HR VT     05/0600Z 14.6N  45.9W    65 KT
 96HR VT     06/0600Z 15.0N  50.0W    75 KT
120HR VT     07/0600Z 16.0N  55.0W    85 KT
 
$$
FORECASTER CANGIALOSI/KIMBERLAIN