000 AXPZ20 KNHC 090849 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC THU AUG 09 2012 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. THE FOLLOWING INFORMATION IS BASED ON SATELLITE IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL ANALYSIS. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0915 UTC. ...SPECIAL FEATURES... AT 09/0600 UTC...HURRICANE GILMA CENTERED NEAR 16.12N 118.6W MOVING W-NW OR 285 DEGREES AT 6 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 984 MB. MAXIMUM SUSTAINED WINDS ARE 70 KT WITH GUSTS TO 85 KT. THE PRESENTATION OF GILMA APPEARS MORE ORGANIZED ON THE LATEST IR SATELLITE IMAGERY. STRONG CONVECTION IS BUILDING WITHIN 60 NM IN THE NE QUADRANT OF THE HURRICANE WITH MODERATE TO STRONG CONVECTION REMAINING WITHIN 120 NM MAINLY ON THE EASTERN SEMICIRCLE. A 0454 UTC ASCAT PASS DIRECTLY OVER THE SYSTEM SHOWED WINDS 20 KT OR GREATER EXTENDING TO WITHIN 120 NM OF THE CENTER. STEADY WEAKENING IS ANTICIPATED STARTING LATE TODAY AS GILMA MOVES OVER PROGRESSIVELY COOLER WATER AND INTO A MORE STABLE AIRMASS. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR MORE DETAILS. A 1010 MB LOW PRES EMBEDDED IN THE MONSOON TROUGH IS LOCATED NEAR 11N102W. CONVECTION TO THE WEST OF THE CENTER HAS WEAKENED CONSIDERABLY OVER THE PAST SIX HOURS. HOWEVER SCATTERED MODERATE CONVECTION IS FORMING IN A LINE N OF THE CENTER FROM 13N100W TO 12N105W. THE CONVECTION IS BEING AIDED IN PART BY AN UPPER CYCLONE CENTERED OFF THE W CENTRAL COAST OF MEXICO NEAR 22N108W. THE SUPPORTING UPPER WINDS WILL BECOME LESS FAVORABLE FOR DEVELOPMENT AS THE UPPER CYCLONE SHIFTS W FOLLOWED BY AN UPPER RIDGE. THIS LEAVES THE SYSTEM WITH A MEDIUM CHANCE OF DEVELOPMENT DEPENDING ON HOW WELL THE CONVECTION PERSISTS AND STAYS TOGETHER AND GLOBAL MODELS GENERALLY ARE DEPICTING THE LOW WEAKENING AN OPENING INTO A TROUGH. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 09N78W TO 09N86W TO 12N93W TO A 1010 MB LOW NEAR 10N103W TO 10N108W. THE MONSOON TROUGH THEN CONTINUES SW OF HURRICANE GILMA FROM 12N123W TO 09N130W TO 09N140W. SCATTERED MODERATE CONVECTION IS NOTED FROM 04N TO 09N BETWEEN 77W AND 87W. SCATTERED MODERATE TO STRONG CONVECTION FROM 09N TO 12N BETWEEN 103W AND 105W. SCATTERED MODERATE CONVECTION FROM 07N TO 10N BETWEEN 125W AND 140W. ...DISCUSSION... SHARP ANTICYCLONIC FLOW ALOFT EXTENDING FROM THE SW UNITED STATES TO NEAR 20N120W IS PROVIDING WEAK STEERING FLOW TO GILMA AS WELL AS UPPER DIVERGENCE TO SUSTAINED CONVECTION ASSOCIATED WITH GILMA. WATER VAPOR AND PRECIPITABLE WATER IMAGERY SHOW FAIRLY DRY IN THE AREA GILMA IS APPROACHING...GENERALLY ACROSS W OF 120W N OF THE ITCZ. AN UPPER SHORT WAVE TROUGH ALONG 135W N OF 30N WILL LIFT OUT TO THE NE...ALLOWING THE SURFACE RIDGE N OF THE AREA TO BUILD SLIGHTLY. WHILE THIS WILL ALLOW A MODEST INCREASE IN TRADE WIND FLOW...IT WILL ALSO PROMOTE NORTHERLY SWELL TO 8 FT REACHING AS FAR SOUTH AS 26N BY LATE FRI. FURTHER SOUTH...BUOY AND SCATTEROMETER DATA SHOW SOUTHERLY WINDS OF 15 TO 20 KT S OF THE ITCZ W OF 120W...SUPPORTING WEAK CONVECTION ALONG THE ITCZ W OF 125W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED FROM 13N TO 16N BETWEEN 92W AND 95W IN THE GULF OF TEHUANTEPEC RELATED TO THE ADVANCE OF TROPICAL STORM ERNESTO JUST TO THE NORTH OF THE AREA IN THE S CENTRAL BAY OF CAMPECHE. SCATTERED CONVECTION IS ALSO NOTED OFF THE COAST OF COLOMBIA THIS MORNING WHERE SW FLOW IN THE LOWER LEVELS IS INTERACTING WITH A TROPICAL WAVE N OF THE AREA MOVING THROUGH THE CENTRAL CARIBBEAN. LOOKING AHEAD TO BEYOND 48 HOURS...GLOBAL MODELS TO INCLUDE THE GFS...ECMWF...UKMET AND NOGAPS ARE IN DECENT AGREEMENT SHOWING THE REMNANTS OF ERNESTO...NOW RACING W THROUGH THE BAY OF CAMPECHE...EMERGING OVER THE PACIFIC OFF MEXICO FRI AND DEEPENING SLIGHTLY NEAR 18N107W BY LATE SAT. CROSS EQUATORIAL LONG PERIOD SW SWELLS OF 16 SECONDS CONTINUE TO IMPACT THE WATERS S OF 05N BETWEEN 95W AND 120W. HOWEVER AN ALTIMETER PASS FROM AROUND 0000 UTC CONFIRMED MWW3 OUTPUT SHOWING SEAS WERE GENERALLY 7 FT OR LESS AND WILL CONTINUE TO SUBSIDE. $$ CHRISTENSEN