Tropical Storm GIL

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TROPICAL STORM GIL DISCUSSION NUMBER  17
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072013
800 AM PDT SAT AUG 03 2013
 
ALTHOUGH SEVERAL BURSTS OF DEEP CONVECTION HAVE OCCURED NEAR THE
CENTER OF GIL DURING THE PAST FEW HOURS...THE STRUCTURE IS STILL
BEING DISTRUPTED BY DEEP-LAYER SHEAR. SATELLITE INTENSITY ESTIMATES
FROM TAFB...SAB...AND UW-CIMSS AVERAGE TO ABOUT 50 KT...AND GIVEN
THAT THE CLOUD STRUCTURE HAS NOT CHANGED SUBSTANTIALLY DURING THE
PAST 6 HOURS...THE INTENSITY HAS BEEN HELD AT AT THAT VALUE. ALL OF
THE INTENSITY MODELS INDICATE THAT GIL WILL WEAKEN DURING THE NEXT
COUPLE OF DAYS WHILE IT INTERACTS WITH AN UPPER-LEVEL TROUGH TO THE
NORTHWEST. AFTER THAT TIME...THE DYNAMICAL MODELS SUGGEST THAT GIL
WILL QUICKLY WEAKEN TO A REMNANT LOW...WHILE THE STATISTICAL MODELS
SUGGEST THAT SOME RESTRENGTHENING COULD OCCUR...PRIMARILY DUE TO
DECREASING SHEAR. THE OFFICIAL FORECAST LIES BETWEEN THESE TWO
POSSIBILITIES AND IS NEAR THE MULTI-MODEL CONSENSUS.

GIL HAS BEEN MOVING STEADILY WESTWARD ALONG THE SOUTHWEST PERIPHERY
OF A MID-LEVEL RIDGE AND THE INITIAL MOTION IS 275/10.  THE GLOBAL
MODELS FORECAST THAT THIS RIDGE WILL BUILD SLIGHTLY TO THE
SOUTHWEST...WHICH SHOULD CAUSE THE TROPICAL CYCLOENN TO TURN TOWARD
THE WEST-SOUTHWEST.  A TURN BACK TOWARD THE WEST IS EXPECTED AS GIL
WEAKENS AND IS STEERED PRIMARILY BY THE LOW-LEVEL EASTERLY FLOW. 
THE TRACK GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT AND THE
GUIDANCE ENVELOPE IS CENTERED AROUND THE PAST COUPLE NHC FORECASTS. 
THE NEW FORECAST IS THEREFORE MERELY AN UPDATE OF THE PREVIOUS
TRACK FORECAST.

FORECAST POSITIONS AND MAX WINDS
 
INIT  03/1500Z 15.0N 132.6W   50 KT  60 MPH
 12H  04/0000Z 15.0N 133.8W   45 KT  50 MPH
 24H  04/1200Z 14.8N 135.3W   45 KT  50 MPH
 36H  05/0000Z 14.4N 136.7W   40 KT  45 MPH
 48H  05/1200Z 14.0N 138.2W   40 KT  45 MPH
 72H  06/1200Z 13.2N 140.8W   35 KT  40 MPH
 96H  07/1200Z 13.0N 143.5W   35 KT  40 MPH
120H  08/1200Z 13.0N 147.0W   30 KT  35 MPH
 
$$
FORECASTER FRANKLIN/ZELINSKY
 
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