000 AXPZ20 KNHC 210923 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI DEC 21 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG 10N85W TO 08N91W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 08N91W TO 06N100W TO 09N120W TO 08N140W. NO SIGNIFICANT CONVECTION IS NOTED. ...DISCUSSION... A COLD FRONT EXTENDING FROM THE CALIFORNIA REDWOOD COAST THROUGH 32N128W TO 26N140W WILL MOVE SLOWLY SE WHILE WEAKENING... EVENTUALLY DISSIPATING BY EARLY SAT. RECENT SCATTEROMETER PASSES INDICATE MAINLY MODERATE TO FRESH WINDS BOTH AHEAD OF AND BEHIND IN THE VICINITY OF THE FRONT N OF 28N. LARGE NW SWELL ASSOCIATED WITH THIS FRONT WILL SPREAD ACROSS THE WESTERN HALF OF THE DISCUSSION AREA THROUGH MON WITH COMBINED SEAS PEAKING AROUND 19 FT ALONG THE NORTHERN BOUNDARY W OF 130W FRI AND SAT. THE WAVE FORECAST CONTINUES TO BE A BLEND OF THE MORE AGGRESSIVE UKMET/NOGAPS WITH THE SHORTER WAVEHEIGHTS PREDICTED BY THE GFS/ECMWF SOLUTIONS. TRADE WINDS EMBEDDED IN THE AREA OF LARGE SWELL WILL BE GENERALLY NE AT 10-20 KT TODAY. HIGH PRESSURE WILL BUILD EASTWARD BEHIND THE FRONT ALONG 26N THROUGH MON NIGHT. THE HIGH WILL BECOME THE DOMINANT SYNOPTIC FEATURE ACROSS THE REGION SAT THROUGH TUE WITH LIGHT WINDS AND SEAS SUBSIDING FROM 15-17 FT TO ONLY 6-8 FT N OF 22N BY CHRISTMAS DAY. THIS HIGH WILL ALSO ENHANCE NE-E TRADE WINDS S OF THE RIDGE AXIS AND N OF THE ITCZ. EXPECT FRESH TO STRONG TRADE WINDS FROM 15N TO 20N W OF 135W BY LATE FRI NIGHT...THEN SPREADING ACROSS THE WATERS FROM 10N TO 20N W OF 125W BY LATE SAT NIGHT. THE COMBINATION OF THESE ENHANCED TRADES WITH CONTINUED LONG-PERIOD NW SWELL SHOULD PRODUCE COMBINED SEAS OF AROUND 12 FT FOR THIS COMING WEEKEND. GAP WINDS... STRONG 1034 MB HIGH PRES IS CENTERED OVER THE RIO GRANDE NEAR 27N99.5W BEHIND A FAST-MOVING COLD FRONT WHICH IS MOVING SOUTHWARD IN THE SE AND SW GULF OF MEXICO. THIS HIGH IS INDUCING A SUDDEN INCREASE IN GAP WINDS THROUGH CHIVELA PASS INTO THE GULF OF TEHUANTEPEC. WHILE THERE HAVE BEEN NO RECENT OBSERVATIONS IN THE VICINITY OF THE GULF OF TEHUANTEPEC...EARLY REPORTS FROM THE SALINA CRUZ WEATHER STATION ALONG THE COAST INDICATED 30 KT N WINDS AT 03 UTC AFTER OBSERVING WEAK WINDS UP UNTIL THEN. WINDS ARE SUDDENLY AND DANGEROUSLY SURGING FROM NEAR CALM CONDITIONS AHEAD OF THE COLD FRONT TO STORM FORCE CONDITIONS VERY RAPIDLY. LATEST MODEL GUIDANCE INDICATES THAT WINDS MAY HAVE ALREADY INCREASED TO STORM FORCE BY 06 UTC WHICH WILL BE REFLECTED IN THIS FORECAST PACKAGE. SEAS WILL RAPIDLY BUILD TO AROUND 22 FT BY LATE FRI NIGHT. GLOBAL MODEL GUIDANCE INDICATES WINDS AT OR NEAR STORM FORCE CONTINUING THROUGH LATE FRI NIGHT...WITH GALE CONDITIONS THEREAFTER THROUGH LATE SAT NIGHT. WIND-DRIVEN SEAS WILL QUICKLY FAN OUTWARD FROM THE SOURCE REGION AS N-NE SWELL EXTENDING DOWNWIND FROM THE GULF OF TEHUANTEPEC TO 110W/112W...MERGING WITH NW SWELL FROM THE COLD FRONT MENTIONED ABOVE. LOOKING AHEAD...THE PRES GRADIENT IS EXPECTED TO RELAX SIGNIFICANTLY OVER THE REGION BY EARLY NEXT WEEK WITH SOUTHERLY FLOW BECOMING ESTABLISHED IN THE SW GULF OF MEXICO BY EARLY MON...ALLOWING FOR WINDS TO DIMINISH TO 5-10 KT IN THE GULF OF TEHUANTEPEC ALONG WITH 3-5 FT SEAS BY MON AFTERNOON. AS TRADEWIND FLOW INCREASES ACROSS THE SW CARIBBEAN BY FRIDAY EXPECT NE TO E WINDS OF 20-25 KT AND SEAS BUILDING TO NEAR 12 FT IN AND DOWNSTREAM OF THE GULF OF PAPAGAYO BY SAT. THESE INCREASING WINDS IN THE SW CARIBBEAN ALSO MAY LEAD TO FRESH TO STRONG NORTHERLY WINDS IN THE GULF OF PANAMA BY LATE SAT NIGHT INTO SUN. A 0523 UTC ASCAT SCATTEROMETER PASS STILL SUGGESTED NW 20-25 KT WINDS IN THE NORTHERN GULF OF CALIFORNIA. FORCING FOR THESE WINDS BETWEEN HIGH PRES OVER THE U.S. GREAT BASIN AND TROUGHING ALONG THE WESTERN COAST OF MEXICO SHOULD RELAX LATER TODAY... WITH WINDS DIMINISHING TO MODERATE TO FRESH BY LATE AFTERNOON. $$ LEWITSKY