000 AXPZ20 KNHC 200340 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC TUE NOV 20 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 09N84W TO 07N90W WHERE IT TRANSITIONS TO ITCZ...CONTINUING TO 05N100W TO 08N115W TO 08N140W. SCATTERED MODERATE CONVECTION IS NOTED FROM 05N TO 09N BETWEEN 117W AND 122W. ...DISCUSSION... ALOFT...AN UPPER LEVEL TROUGH EXTENDS FROM NORTHERN BAJA CALIFORNIA TO NEAR 18N121W. STRONG NW JET TO 80 KT IS DIVING SE THROUGH THE BASE OF THE TROUGH. STRONG SW FLOW TO 70 KT IS NOTED FROM THE BASE OF THE TROUGH TO THE NE ACROSS CENTRAL BAJA CALIFORNIA AND NW MEXICO INTO THE SW CONUS WHERE WINDS INCREASE TO 110 KT. THESE STRONG WINDS ARE ADVECTING ABUNDANT MID/UPPER LEVEL MOISTURE. SATELLITE IMAGERY CONTINUES TO SHOWS A WIDE BAND OF TRANSVERSE HIGH CLOUDS IN ASSOCIATION WITH THESE WINDS. A RIDGE IS NOTED W OF THE TROUGH AXIS ROUGHLY EXTENDING FROM 20N132W TO BEYOND 31N123W WITH A SHORT-WAVE TROUGH CURRENTLY OVER THE FAR NW PART OF THE FORECAST AREA. AN UPPER ANTICYCLONE IS CENTERED NEAR 14N100W...AND COVERS THE AREA N OF 10N BETWEEN 90W AND 110W. TO THE E OF THE RIDGE...PERSISTENT UPPER TROUGH EXTENDS FROM A CUT-OFF LOW JUST OFF THE SE U.S. COAST...S-SW ACROSS THE NW BAHAMAS AND THE NW CARIBBEAN TO CENTRAL AMERICA NEAR 14N90W. A LINGERING TUTT AXIS STRETCHES FROM 10N89W TO 07N110W TO THE EQUATOR AT 112W. SW FLOW PERSISTS E OF 90W FROM THE EQUATOR ACROSS COSTA RICA AND PANAMA INTO THE CARIBBEAN SEA. MODERATE TO STRONG SUBSIDENCE OCCURRING N OF THE TUTT AXIS CONTINUES TO DOMINATE THE AREA E OF 110W...AND IS LIMITING CONVECTION ALONG THE MONSOON TROUGH AND THE ITCZ AXIS. UPPER DIFFLUENCE IS HELPING TO INDUCE CONVECTION ALONG THE ITCZ W OF 110W. AT THE SURFACE...A 1023 MB HIGH PRES CENTER HAS DEVELOPED OVER THE N WATERS NEAR 29N126W...AND EXTENDS A RIDGE SE TO NEAR 20N110W. PRES GRADIENT BETWEEN THE RIDGE A LOWER PRES ALONG THE ITCZ IS PRODUCING A BELT OF TRADE WINDS 20-25 KT FROM 09N TO 20N W OF 120W. THIS WEATHER PATTERN WILL PERSIST OVER THE NEXT COUPLE OF DAYS...WHICH WILL MAINTAIN A FAIRLY BROAD ZONE OF FRESH TO STRONG TRADES WITH SEAS OF 8 TO 10 FT ACROSS THIS AREA. LONG PERIOD NW SWELL CONTINUES TO PROPAGATE ACROSS THE REGIONAL WATERS MAINLY W OF 110W AND NOW ARE RAISING SEAS TO 9 FT N OF 20N W OF 115W. THESE SWELLS WILL COMBINE WITH NE WIND WAVES DEVELOPING WITHIN THE TRADE WIND ZONE TO MAINTAIN COMBINED SEAS OF 8 TO 10 FT WITHIN THE TRADE WIND BELT. THE NEXT COLD FRONT IS FORECAST TO REACH THE FAR NW PORTION OF THE AREA LATE TUE THEN WILL MOVE BACK N OF AREA AND DISSIPATE BY WED AS ANOTHER STRONGER COLD FRONT MOVES ACROSS THE NE PACIFIC. NW SWELL IN THE WAKE OF THE FRONT WILL THEN SPREAD E AND SE ACROSS THE NW WATERS RAISING SEAS TO 12 FT BY EARLY WED. GAP WINDS... PERSISTENT STRONG TO GALE FORCE NORTHERLY WINDS CONTINUE TO BLOW THROUGH THE GULF OF TEHUANTEPEC. THE 1854 OSCAT PASS PROVIDED OBSERVATIONS OF 30-35 KT WINDS ACROSS THE AREA WHILE IXTEPEC IN THE STATE OF OAXACA MEXICO REPORTED GUSTY WINDS OF 30-35 KT FOR SEVERAL HOURS. WINDS EXITING THE CHIVELAS PASS CONTINUE TO BE ENHANCED BY NOCTURNAL DRAINAGE FLOW ACROSS THE GULF OF TEHUANTEPEC...AND HAVE BEEN REACHING MINIMAL GALE FORCE ROUGHLY BETWEEN 0600 AND 1200 UTC EACH OF THE PAST FEW DAYS. GLOBAL MODELS SUGGEST THAT THIS PATTERN WILL CONTINUE THROUGH WEDNESDAY BEFORE WINDS ACROSS THE SW GULF BEGIN TO TURN MORE E AND DIMINISH INFLUENCE ACROSS THE CHIVELAS PASS. A GALE WARNING THEREFORE REMAINS IN EFFECT FOR THE GULF TEHUANTEPEC THROUGH WEDNESDAY EVENING...WITH WINDS LIKELY AT OR JUST BELOW GALE FORCE OCCURRING DURING THE AFTERNOON HOURS. SEE LATEST NHC HIGH SEAS FORECAST UNDER AWIPS/WMO HEADERS HSFEP2/FZPN03 KNHC FOR DETAILS. PULSING OF NOCTURNAL WINDS ARE ALSO EXPECTED TO CONTINUE ACROSS THE GULF OF PAPAGAYO...WITH NOCTURNAL WINDS FORECAST TO REACH AROUND 20 KT FROM 0600 TO 1200 UTC...WITH SEAS OF 6-7 FT THROUGH AND DOWNWIND OF THE GULF. MARINE GUIDANCE SUGGESTS INCREASING WINDS TO 25 KT AND SEAS OF 8 FT ACROSS THIS GULF BY THU MORNING. EXPECT INCREASING WINDS 20-25 KT ACROSS THE GULF OF CALIFORNIA TONIGHT AS PRES GRADIENT BETWEEN THE AFOREMENTIONED HIGH PRES AND A SEMI-PERMANENT TROUGH ACROSS WESTERN MEXICO TIGHTENS. THIS WILL BE A SHORT-LIVED EVENT. WINDS ARE FORECAST TO DIMINISH TO 20 KT OR LESS BY WED. $$ GR