000 AXPZ20 KNHC 080930 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED AUG 08 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 0845 UTC. ...SPECIAL FEATURES... GILMA IS NEARING HURRICANE STRENGTH. AT 08/0900 UTC...IT IS CENTERED AT 15.6N 116.1W MOVING W-NW OR 285 DEGREES AT 11 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. PLEASE SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR MORE DETAILS. NUMEROUS MODERATE TO STRONG CONVECTION IS NOTED WITHIN 45 NM OF CENTER. SIMILAR CONVECTION CAN BE FOUND IN A BAND W OF CENTER ALONG 18N117W 16N117W 15N116W...AND S OF THE CENTER FROM 12N TO 14N BETWEEN 117W AND 120W. GILMA CONTINUES TO BECOME BETTER ORGANIZED OVER WARM WATERS AND IN A LOW SHEAR ENVIRONMENT. THEREFORE...IT IS FORECAST TO BECOME A HURRICANE TODAY. A 1008 MB LOW PRES EMBEDDED IN THE MONSOON TROUGH IS LOCATED NEAR 10.5N102W. SHOWER AND THUNDERSTORM ACTIVITY ASSOCIATED WITH THIS SYSTEM HAVE DIMINISHED SOME OVERNIGHT AND NO DEEP CONVECTION IS NOTED NEAR THE LOW CENTER. HOWEVER...DEVELOPMENT OF THIS SYSTEM IS POSSIBLE AND IT COULD BECOME A TROPICAL DEPRESSION DURING THE NEXT COUPLE OF DAYS. CURRENTLY...THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE AS IT DRIFTS GENERALLY WESTWARD DURING THE NEXT 48 HOURS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 10N85W TO 1008 MB LOW PRES NEAR 10.5N102W TO 13N108W THEN CONTINUES W OF T.S. GILMA FROM 13N118W TO 08N134W. ITCZ AXIS IS FROM 08N134W TO BEYOND 10N140W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED FROM 08N TO 12N BETWEEN 100W AND 104W...AND FROM 06N TO 08N BETWEEN 126W AND 134W. ...DISCUSSION... ALOFT...AN ANTICYCLONE OVER ARIZONA EXTENDS A RIDGE SOUTHWARD THROUGH BAJA CALIFORNIA TO NEAR T.S. GILMA. UPPER DIFFLUENCE ASSOCIATED WITH THIS RIDGE IS HELPING TO SUSTAIN THE DEEP CONVECTION ASSOCIATED WITH THIS TROPICAL CYCLONE. W OF THE RIDGE...THERE IS AN UPPER LEVEL LOW SPINNING NEAR 22N126W. THE WEST-CENTRAL PORTION OF THE FORECAST AREA IS DOMINATING BY ANOTHER ANTICYCLONE CENTERED NEAR 17N141W. STRONG W TO SW FLOW AHEAD OF A LONG WAVE TROUGH IS AFFECTING THE NW CORNER OF THE AREA. THESE WINDS ARE TRANSPORTING ABUNDANT MID/UPPER LEVEL MOSITURE. NE WINDS ALOFT ARE MAINLY S OF 12N AND E OF 110W. THESE WINDS ARE ENHANCING THE CONVECTION NEAR THE MONSOON TROUGH. A 1025 MB HIGH PRES LOCATED NEAR 34N141W EXTENDS A RIDGE OVER THE N WATERS TO NEAR 24N115W. THIS SYSTEM IS FORECAST TO MOVES NE AND SLIGHTLY INTENSIFY. TRADE WINDS IN THE 20 TO 25 KT RANGE ARE SEEN PER THE 0654 UTC ASCAT PASS COVERING THE AREA FROM 11N TO 17N W OF 134W. AS THE HIGH PRES MOVES NE...EXPECT THE AREA OF TRADES TO SHRINK WWD. AT THE SAME TIME...THE PRES GRADIENT WILL TIGHTEN NEAR THE COAST OF CALIFORNIA AND JUST N OF THE FORECAST REGION RESULTING IN NLY WINDS OF 20 KT OVER THE N WATERS MAINLY N OF 27N AND W OF 120W. SEAS OF AROUND 8 FT GENERATED BY THESE WINDS WILL REACH 30N THU NIGHT. CROSS EQUATORIAL LONG PERIOD SW SWELLS OF 17-18 SECONDS ARE NOW IMPACTING THE SOUTH-CENTRAL WATERS RAISING SEAS TO 8 FT MAINLY S OF 06N BETWEEN 115W AND 126W. THIS SWELL EVENT WILL CONTINUE TO PROPAGATE NWD OVER THE NEXT COUPLE OF DAYS...BUT SEAS WILL SUBSIDE TO LESS THAN 8 FT IN ABOUT 36-48 HOURS. GAP WINDS...20 TO 25 KT NORTHERLY WINDS ARE FUNNELING THROUGH THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC. WINDS ARE EXPECTED TO PERSIST FOR ONLY 24 HOURS. THESE WINDS ARE BEING INDUCED BY THE APPROACH OF HURRICANE ERNESTO. $$ GR