Tropical Storm GIL

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TROPICAL STORM GIL DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       EP072013
800 PM PDT TUE JUL 30 2013
 
CONVENTIONAL AND MICROWAVE SATELLITE IMAGERY CONTINUES TO SHOW
INCREASED ORGANIZATION OF BOTH THE INNER CORE CONVECTION AND
OUTER CONVECTIVE BANDING FEATURES. A RECENT AMSU OVERPASS AT
30/2227 UTC INDICATED A LARGE CURVED BAND OF CONVECTION WRAPPING
MORE THAN 70 PERCENT AROUND THE CIRCULATION CENTER. THE INITIAL
INTENSITY OF 40 KT IS BASED ON A BLEND OF SATELLITE INTENSITY
ESTIMATES OF T2.5/35 KT FROM TAFB AND ADT...AND A 2124 UTC AMSU
ESTIMATE OF 48 KT. UPPER-LEVEL OUTFLOW IS SYMMETRICAL AND
EXPANDING...WITH A WEAK POLEWARD OUTFLOW CHANNEL HAVING BECOME
BECOME ESTABLISHED SINCE THE LAST ADVISORY.
 
THE INITIAL MOTION ESTIMATE REAMINS 285/13 BASED ON VISIBLE AND
MICROWAVE SATELLITE FIX DATA.  A MID-LEVEL RIDGE EXTENDS WESTWARD
FROM THE SOUTHWESTERN UNITED STATES ACROSS THE EASTERN NORTH PACIFIC
TO THE NORTH OF GIL. THIS VERY STABLE STEERING FLOW PATTERN IS
EXPECTED TO KEEP THE CYCLONE MOVING IN A GENERAL WEST-NORTHWESTWARD
MOTION FOR THE NEXT 3-4 DAYS...FOLLOWED BY A GRADUAL TURN TOWARD
THE WEST THEREAFTER. A GRADUAL DECREASE IN FORWARD SPEED IS
FORECAST BY 24-36 HOURS AS GIL APPROACHES A WEAKNESS IN THE
SUBTROPICAL RIDGE. THE OFFICIAL FORECAST IS BASICALLY JUST AN
UPDATE OF THE THE PREVIOUS ADVISORY TRACK...AND IS CLOSE TO BUT
SLIGHTLY SLOWER THAN THE MULTI-MODEL CONSENSUS TVCE.
 
BASED ON THE LAST FEW VISIBLE SATELLITE IMAGES SHOWING A CDO-LIKE
FEATURE DEVELOPING...PLUS THE PRONOUNCED BANDING FEATURE NOTED IN
THE LATEST AMSU MICROWAVE DATA...GIL APPEARS POISED TO STEADILY
INTENSIFY FOR AT LEAST THE NEXT 48 HOURS. GIVEN THE CURRENT OUTFLOW
PATTERN THAT IS FORECAST BY THE GFS MODEL TO CONTINUE TO DEVELOP
AND EXPAND...THE OFFICIAL INTENSITY FORECAST COULD BE TOO LOW.
REGARDLESS...OF THE DEVELOPMENT RATE...ENVIRONMENTAL CONDITIONS ARE
CONDUCIVE FOR AT LEAST MODEST STRENGTHENING TO OCCUR...AND THE
CYCLONE IS EXPECTED TO BECOME A HURRICANE BY 48 HOURS. AFTER A
SHORT LEVELING OFF PERIOD...GIL IS EXPECTED TO BEGIN A SLOW
WEAKENING TREND BY 96 HOURS AS THE CYCLONE MOVES OVER SLIGHTLY
COOLER WATER AND INTO A DRIER AND MORE STABLE AIRMASS. THE
INTENSITY FORECAST IS SIMILAR TO THE PREVIOUS ADVISORY AND IS CLOSE
TO A BLEND OF THE SHIPS AND LGEM STATISTICAL-DYNAMICAL MODELS.
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  31/0300Z 13.1N 117.6W   40 KT  45 MPH
 12H  31/1200Z 13.6N 119.3W   50 KT  60 MPH
 24H  01/0000Z 14.2N 121.5W   55 KT  65 MPH
 36H  01/1200Z 14.7N 123.5W   60 KT  70 MPH
 48H  02/0000Z 15.2N 125.5W   65 KT  75 MPH
 72H  03/0000Z 15.9N 128.8W   65 KT  75 MPH
 96H  04/0000Z 16.4N 132.0W   55 KT  65 MPH
120H  05/0000Z 16.5N 135.5W   45 KT  50 MPH
 
$$
FORECASTER STEWART
 
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