000 AXPZ20 KNHC 201525 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG 08N78W TO 05N95W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 05N95W TO 08N115W TO 08N125W TO 08N140W. ISOLATED TO SCATTERED MODERATE CONVECTION IS WITHIN 120-150 NM EITHER SIDE OF THE ITCZ W OF 115W. ...DISCUSSION... ALOFT...A WEAKENING UPPER LEVEL TROUGH IS SWEEPING EASTWARD ACROSS THE CENTRAL U.S. WITH A CONNECTION TO AN UPPER LEVEL TROUGH EXTENDING SW INTO THE DISCUSSION AREA...FROM THE NORTHERN BAJA CALIFORNIA TO AN ELONGATED MIDDLE TO UPPER LEVEL CYCLONE NEAR 30N116W WHICH IS MOVING TO THE N-NE...WITH THE TROUGH CONTINUING TO TH S-SW NEAR 16N122W. A 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. A FLAT EQUATORIAL UPPER RIDGE PREVAILS TO THE SW...CENTERED ON AN UPPER ANTICYCLONE NEAR 08N130W...WITH WESTERLIES DOMINATING FROM 08N TO 23N W OF THE UPPER TROUGH AXIS. DOWNSTREAM...A BROAD UPPER RIDGE PERSISTS N OF 10N BETWEEN 86W AND 112W...WITH A TUTT AXIS SNAKING IN UNDERNEATH THE RIDGE FROM THE NW CARIBBEAN SEA...ACROSS CENTRAL AMERICA TO A TUTT CELL NEAR 12N90W. CONVERGENCE ALONG THE S SIDE OF THE RIDGE AND WITHIN THE TUTT IS PRODUCING STRONG CONVERGENCE WHICH IS LIMITING CONVECTION ALONG THE MONSOON TROUGH AND ITCZ E OF 105W. THE UPPER LEVEL CYCLONE IS FORECAST TO MOVE NE AND ACROSS BAJA CALIFORNIA...NW MEXICO...AND INTO THE DESERT SW OF THE U.S. DURING THE NEXT 36-48 HOURS AS A SHORTWAVE TROUGH MOVES ACROSS NW PORTIONS OF THE WATERS. AT THE SURFACE...1022 MB HIGH PRES IS OVER THE N CENTRAL WATERS NEAR 29N126W WITH A RIDGE EXTENDING TO THE SE WITH A TERMINUS NEAR 13N105W. THE PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES ALONG THE ITCZ IS PRODUCING A NARROW BELT OF FRESH TO STRONG TRADE WINDS FROM 14N TO 18N W OF 130W. TO THE E OF THE RIDGE... FRESH NW-N FLOW IS OCCURRING ALONG THE W COAST OF THE BAJA PENINSULA AS INDICATED BY EARLIER ASCAT DATA AND NEARBY SHIP OBSERVATIONS. A SURFACE TROUGH IS ALONG THE E GULF OF CALIFORNIA COAST AND THE PRES GRADIENT BETWEEN THIS TROUGH AND THE RIDGING TO THE W IS PRODUCING NW-N FRESH TO STRONG WINDS IN THE GULF OF CALIFORNIA FROM 22N TO 28N WITH SEAS TO 8 FT AT THE SOUTHERN TAIL OF THE GULF S OF 24N. THESE WINDS ARE FORECAST TO DIMINISH TO 20 KT OR LESS AS THE TROUGHING WEAKENS. LONG PERIOD NW SWELL CONTINUES TO PROPAGATE ACROSS THE REGIONAL WATERS MAINLY W OF 115W...WITH A NEW AND REINFORCING SET MOVING INTO THE NW WATERS UP TO 12 FT AS REPORTED AT 12 UTC BY A SHIP WITH CALL-SIGN WFLH NEAR 29.5N136W. THIS OBSERVATION WAS 2-3 FT ABOVE THE MAJORITY OF THE WAVE MODEL GUIDANCE. THIS NEW SET OF SWELL IS COMBINING WITH A LONGER PERIOD SET OF NW SWELL OF 8 FT OR GREATER WHICH REACHES S ALL THE WAY TO 05N. THE SWELL WILL ALSO COMBINE WITH NE WIND WAVES DEVELOPING WITHIN THE TRADE WIND ZONE DESCRIBED ABOVE TO MAINTAIN COMBINED SEAS TO 10 FT WITHIN THE TRADE WIND BELT. THE NEXT COLD FRONT IS FORECAST TO REACH THE FAR NW PORTION OF THE AREA TONIGHT...THEN WILL MOVE BACK N OF THE AREA AS A WARM FRONT WED NIGHT AND WILL DISSIPATE BY THU. 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 THE HOURS OF 0600 AND 1500 UTC EACH OF THE PAST FEW DAYS. GLOBAL MODELS SUGGEST THAT THIS PATTERN WILL CONTINUE THROUGH EARLY THU BEFORE WINDS ACROSS THE SW GULF BEGIN TO TURN MORE E DIMINISHING THEIR INFLUENCE ACROSS THE CHIVELAS PASS. THUS A GALE WARNING REMAINS IN EFFECT THROUGH EARLY THU MORNING. WINDS MAY BRIEFLY DROP BELOW GALE FORCE THROUGH THE NEXT 48 HOURS ALTHOUGH OPTED TO KEEP THE WARNING UP THROUGH THEN. PULSING OF NOCTURNAL WINDS ARE ALSO EXPECTED TO CONTINUE ACROSS THE GULF OF PAPAGAYO...WITH WINDS TO 25 KT AND SEAS OF 8-9 FT THROUGH LATER THIS AFTERNOON...THEN WILL DIMINISH TO 20 KT OR LESS WITH ANOTHER SURGE FORECAST BY THU MORNING. $$ LEWITSKY