000 AXPZ20 KNHC 201000 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 08N74W TO 10N84W TO 05N95W WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 08N123W TO BEYOND 08N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED FROM 05N TO 10N W OF 111W. ...DISCUSSION... ALOFT...UPPER LEVEL TROUGH SWEEPING EWD ACROSS THE CENTRAL U.S. IS GRADUALLY WEAKENING CONNECTION TO UPPER LEVEL TROUGH EXTENDING SW INTO THE AREA...FROM NORTHERN BAJA CALIFORNIA TO AN ELONGATED MIDDLE TO UPPER LEVEL CYCLONE NEAR 26N119W...CONTINUING TO 15N121W. BROAD ZONE OF OVERCAST MIDDLE AND HIGH CLOUDS CONTINUE TO THE E OF TROUGH AXIS...SPREADING NE ACROSS BAJA CALIFORNIA AND NW MEXICO EMBEDDED IN A 50-75 KT JET. CYCLONE HAS ROTATED CYCLONICALLY PST 24 HOURS AND NOW ALIGNED N TO S...WITH BASE OF TROUGH SHIFTING EWD. A FLAT EQUATORIAL UPPER RIDGE PREVAILS TO THE SW...CENTERED ON AN UPPER CYCLONE NEAR 08N128W...WITH WESTERLIES DOMINATING FROM 13N TO 24N W OF TROUGH AXIS. DOWNSTREAM BROAD UPPER RIDGE PERSISTS N OF 10N BETWEEN 86W AND 112W...WITH TUTT AXIS SNAKING IN UNDERNEATH RIDGE FROM NW CARIBBEAN...ACROSS CENTRAL AMERICA TO TUTT CELL NEAR 10N92W. CONVERGENCE ALONG S SIDE OF RIDGE AND WITHIN TUTT PRODUCING STRONG CONVERGENCE AND LIMITING CONVECTION ALONG MONSOON TROUGH AND ITCZ E OF 105W. UPPER CYCLONE ABOVE FORECAST TO MOVE NE AND ACROSS BAJA CALIFORNIA...NW MEXICO...AND INTO THE DESERT SW OF THE U.S. NEXT 36-48 HOURS AS A SHORTWAVE TROUGH MOVES ACROSS NW PORTIONS AND THROUGH BASE OF BROAD TROUGH CURRENTLY ACROSS NE PACIFIC. AT THE SURFACE...A 1024 MB HIGH PRES CENTER HAS DEVELOPED OVER THE N WATERS NEAR 29N126W...AND EXTENDS A RIDGE SE TO NEAR 17N106W. PRES GRADIENT BETWEEN THE RIDGE A LOWER PRES ALONG THE ITCZ IS PRODUCING A NARROW BELT OF FRESH TRADE WINDS 20-25 KT FROM 13N TO 19N W OF 120W. TO THE E OF THE HIGH..TIGHTENING PRES GRADIENT IS FRESHENING THE NLY WIND FLOW ALONG THE W COAST OF THE BAJA PENINSULA...WITH WINDS AROUND 20 KT N OF 27N PER RECENT SCATTEROMETER PASSES. WINDS HAVE INCREASE MORE SIGNIFICANTLY INSIDE THE GULF OF CALIFORNIA...WITH 20-25 KT NWLY WINDS BLOWING S TO 22N...AND SEAS REACHING NEAR 8 FT BETWEEN 22N AND 24N. THIS PATTERN WILL PERSIST THROUGH THE NEXT 24 HOURS BEFORE THE ELONGATED LOW PRES TROUGH ACROSS THE SIERRA MADRES SHIFTS SE AND THE GRADIENT...AND ASSOCIATED WINDS...DECREASE ON WEDNESDAY. LONG PERIOD NW SWELL CONTINUES TO PROPAGATE ACROSS THE REGIONAL WATERS MAINLY W OF 110W...WITH A NEW PULSE OF SWELL MOVING INTO THE NW WATERS AT 9 TO 10 FT. THIS NW SWELL WILL INCREASE DURING THE NEXT 24 HOURS...BUILDING SEAS TO 8 TO 12 FT ACROSS NW PORTIONS BY WED MORNING. THIS SWELL WILL ALSO COMBINE WITH NE WIND WAVES DEVELOPING WITHIN THE TRADE WIND ZONE TO MAINTAIN COMBINED SEAS OF 8 TO 11 FT WITHIN THE TRADE WIND BELT. THE NEXT COLD FRONT IS FORECAST TO REACH THE FAR NW PORTION OF THE AREA LATE TODAY THEN WILL MOVE BACK N OF AREA AND DISSIPATE BY WED AS ANOTHER STRONGER COLD FRONT MOVES ACROSS THE NE PACIFIC. GAP WINDS... PERSISTENT STRONG TO GALE FORCE NORTHERLY WINDS CONTINUE TO BLOW THROUGH THE GULF OF TEHUANTEPEC. 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 EARLY THU MORNING...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. MODEL GUIDANCE SUGGESTS INCREASING WINDS TO 25 KT AND SEAS OF 8 FT ACROSS THIS GULF BY THU MORNING. $$ STRIPLING