000 AXPZ20 KNHC 190904 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI APR 19 2013 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 FROM 06N77W TO 09N85W TO 06N110W. ITCZ FROM 06N110W TO 08N122W...THEN BREAKING AT A SURFACE TROUGH EXTENDING FROM 11N120W TO 04N125W. THE ITCZ CONTINUES FROM FROM 06N125W TO 03N140W. SCATTERED MODERATE TO STRONG CONVECTION WITHIN 240 NM S OF AXIS BETWEEN 85W AND 95W. SCATTERED MODERATE CONVECTION WITH 60 NM EAST OF SURFACE TROUGH AXIS. ...DISCUSSION... GULF OF TEHUANTEPEC...STRONG NORTHERLY FLOW BEHIND A COLD FRONT MOVING ACROSS THE WESTERN GULF OF MEXICO WILL PUSH THROUGH THE CHIVELA PASS AND DELIVER GALES TO THE GULF OF TEHUANTEPEC STARTING THIS EVENING...AND PERSISTING THROUGH EARLY SAT BEFORE DIMINISHING RAPIDLY TO BELOW 20 KT BY EARLY SUN. SEAS FORECAST FOLLOWS MWW3 AND UKMET WAVE GUIDANCE SHOWING RAPID INCREASE TO 14 FT IN AREA OF GALE FORCE WINDS BY EARLY SAT. A PLUME OF FRESH SWELL IN EXCESS OF 8 FT WILL REACH AS FAR AS 500 NM TO THE SW OF THE GULF OF TEHUANTEPEC THROUGH SUN. GULF OF CALIFORNIA...LAND BASED OBSERVATIONS AND AN ALTIMETER PASS FROM YESTERDAY AFTERNOON INDICATED FRESH TO STRONG NW WINDS IN THE GULF OF CALIFORNIA. THIS IS LIKELY THE RESULT OF A TIGHT PRES GRADIENT RELATED TO SOMEWHAT STRONG HIGH PRES SET UP OVER THE GREAT BASIN AND DEEP 1002 MB LOW PRES OVER N CENTRAL MEXICO. GLOBAL MODELS ARE IN GOOD AGREEMENT SHOWING THIS FLOW PERSISTING THROUGH FRI...AND MWW3 AND EC WAVE OUTPUT SHOWS SEAS UP TO 10 FT IN THE SOUTHERN HALF OF THE GULF BY AFTERNOON DUE TO THE LONG DURATION AND FETCH OF THE STRONG FLOW. ELSEWHERE E OF 110W...GOES DERIVED HIGH DENSITY WINDS HELPED DEFINE A SHARP UPPER TROUGH EXTENDING FROM THE JAMAICA ACROSS NORTHERN CENTRAL AMERICA TO 10N92W. UPPER DIVERGENCE ON THE SE SIDE OF THIS TROUGH ALONG WITH HIGH DEEP LAYER MOISTURE AND MODEST SW FLOW IS SUPPORTING CLUSTERS OF MODERATE TO STRONG CONVECTION WITHIN 240 NM S OF AXIS BETWEEN 85W AND 95W. MEANWHILE GLOBAL WAVE MODELS REMAIN IN DECENT AGREEMENT SHOWING SW SWELL WITH HEIGHTS APPROACHING 8 FT IS MOVING ACROSS THE EQUATOR. THIS WILL MIX WITH THE DECAYING NE SWELL FROM THE TEHUANTEPEC GALE EVENT CREATING AN AREA OF CONFUSED SEAS WITH HEIGHTS TO 9 FT IN THE AREA FROM 07N TO 12N BETWEEN 90W AND 100W...WITH SW SWELL TO 8 FT COVERING THE REMAINING AREA S OF 10N BETWEEN 90W AND 120W THROUGH EARLY SUN. W OF 110W...A MID TO UPPER LEVEL CYCLONE IS CENTERED NEAR 27N145W. THIS FEATURE IS WELL DEFINED ON WATER VAPOR IMAGERY WITH A TROUGH TRAILING SOUTH TO 09N140W. STRONG BOUNDARY LAYER RIDGING DOMINATES THE LOWER LEVELS BENEATH THE UPPER LOW HOWEVER...WITH A 1030 MB HIGH CENTERED NEAR 38N138W. SCATTEROMETER DATA INDICATE A BROAD AREA OF 20 KT TRADES FROM 10N TO 20N W OF 135W S OF THE RIDGE. DESPITE CONVERGENCE OF THE TRADES INTO THE ITCZ IN CONJUNCTION WITH UPPER DIVERGENCE RELATED TO THE UPPER TROUGH TO THE NW...CONVECTION REMAINS FAIRLY LIMITED FOR THE MOMENT W OF 125W...LARGELY DUE TO LIMITED DEEP LAYER MOISTURE. A SURFACE TROUGH IS EMBEDDED IN THE ITCZ BETWEEN 120W AND 125W...IN AN A FAVORABLE GROWTH AREA BETWEEN THE UPPER TROUGH TO THE WEST AND AN UPPER RIDGE CENTERED NEAR 15N105W. CLUSTERS OF CONVECTION WITHIN 60 NM TO THE E OF TROUGH AXIS ARE NOTED. INTO EARLY NEXT WEEK...THE HIGH PRES N OF THE AREA WILL BE REINFORCED AS A BLOCKING RIDGE BUILDS OVER THE NE PACIFIC N OF 30N. THIS WILL ALLOW A INCREASE IN NORTHERLY WINDS ALONG THE CALIFORNIA COAST THROUGH SAT...REACHING SOUTH OF 30N BY LATE SAT ACCOMPANIED BY SEAS TO 8 TO 10 FT. ECMWF SHOWS NORTHERLY WINDS AND SEAS IN EXCESS OF 8 FT PENETRATING AS FAR S AS 25N. ECWAVE OUTPUT INITIALIZES A LITTLE TOO STRONG COMPARED TO ALTIMETER OUTPUT...AND FORECAST FAVORS SLIGHTLY WEAKER GFS/MWW3 OUTPUT INDICATING WINDS OF 20 TO 25 KT AND SEAS TO 9 FT PUSHING S TO 28N BETWEEN 120W AND 125W BY EARLY SUN. THESE WINDS AND SEAS SUBSIDE THROUGH MON. $$ CHRISTENSEN