000 AXPZ20 KNHC 040936 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC TUE DEC 04 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 07N78W TO 09N87W TO 07N96W WHERE IT TRANSITIONS TO THE ITCZ EXTENDING TO 06N120W TO BEYOND 06N140W. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 90 NM N OF ITCZ AXIS BETWEEN 105W AND 109W. ...DISCUSSION... ALOFT...A RIDGE/TROUGH/RIDGE PATTERN DOMINATES THE AREA W OF 100W. A SHARP UPPER TROUGH EXTENDS FROM NW MEXICO THROUGH SOUTHERN BAJA CALIFORNIA TO 20N125W THEN CONTINUES SOUTH TO 10N135W. MODERATE TO STRONG SUBSIDENCE AND IMPLIED DRY AIR MASS IN NOTED ALONG AND BEHIND THE TROUGH AXIS. AN ANTICYCLONIC CIRCULATION IS CENTERED NEAR 11N105W. ABUNDANT MID/UPPER LEVEL MOISTURE IS OBSERVED ON WATER VAPOR IMAGERY BETWEEN THESE TWO UPPER-LEVEL FEATURES. A RIDGE PERSISTS OVER NORTHERN SOUTH AMERICA...CENTRAL AMERICA AND THE EPAC WATERS E OF 95W. AT THE SURFACE...HIGH PRES CENTERED OVER THE N WATERS DURING THE PREVIOUS DAYS HAS SLIGHTLY STRENGTHENED A NOW HAS A 1024 MB CENTER NEAR 28N124W. SCATTEROMETER DATA PROVIDED OBSERVATIONS OF 20 KT WINDS OFF THE NORTHERN COAST OF BAJA CALIFORNIA...ON THE EAST SIDE OF THE HIGH PRES. AN EARLIER ASCAT PASS AND THE 0322 UTC WINDSAT PASS INDICATED 20 TO 25 KT TRADE WINDS FROM 08N TO 18N W OF 128W ON THE SOUTHERN PERIPHERY OF THE RIDGE. NW SWELL COVERS MOST OF THE REGIONAL WATERS W OF 110W...MIXING WITH FRESH NE SWELL IN THE REGION OF 20 TO 25 KT TRADES. A WEAK TROUGH IS ANALYZED ON THE 0600 UTC SURFACE MAP AND RUNS FROM 13N122W TO 08N124W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS NOTED MAINLY FROM 09N TO 12N BETWEEN 116W AND THE TROUGH AXIS...AIDED IN PART BY THE AFOREMENTIONED SHARP UPPER TROUGH. LOOKING AHEAD...EXPECT INCREASING WINDS AND BUILDING SEAS OFF THE NORTHERN COAST OF BAJA CALIFORNIA BY THU AS A 1029 MB HIGH PRES SETTLES NEAR 38N140W. THEN...THE HIGH PRES WILL MOVE SE AND THE PRES GRADIENT WILL TIGHTEN BETWEEN THE HIGH AND LOWER PRES ALONG WESTERN MEXICO RESULTING IN NLY WINDS OF 20-25 KT OVER THE NE WATERS WITH SEAS OF 8-10 FT BY FRI MORNING. GAP WINDS... LATEST SCATTEROMETER DATA INDICATES GAP WIND FLOW THROUGH THE GULF OF TEHUANTEPEC HAS DIMINISHED TO 20 KT OR LESS. THERE WILL LIKELY BE A BRIEF PULSE OF 20 KT OR EVEN A LITTLE HIGHER EARLY THIS MORNING...BUT THE GENERAL PATTERN DOES NOT SUPPORT STRONG GAP WINDS TODAY. A COLD FRONT IS EXPECTED TO MOVE INTO THE GULF OF MEXICO BY TONIGHT...AND DELIVER A ROUND OF COOLER AND DRIER AIR DOWN THE GULF COAST OF MEXICO...THROUGH THE CHIVELA PASS AND INTO THE GULF OF TEHUANTEPEC BY LATE TUE NIGHT. BASED ON MARINE GUIDANCE...WINDS ARE EXPECTED TO REACH 30 KT BY WED WITH SEAS BUILDING TO 9 FT...THEN WILL APPROACH GALE FORCE BRIEFLY BY THU MORNING AS HIGH PRES BUILDS TO THE NORTH. WINDS WILL CONTINUE TO PULSE IN THE GULF OF PAPAGAYO TO 20 KT DURING LATE NIGHT AND EARLY MORNING HOURS THEN DIMINISH BELOW 15 KT IN THE AFTERNOON THROUGH FRI. $$ GR