000 AXPZ20 KNHC 081603 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC TUE DEC 08 2015 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. ...SPECIAL FEATURES... GULF OF TEHUANTEPEC GALE WARNING...A TIGHT PRESSURE GRADIENT PERSISTS ACROSS SOUTHERN MEXICO SUPPORTING GALE FORCE NORTHERLY WINDS. AN OSCAT PASS FROM 08 UTC INDICATED GAP WINDS TO AT LEAST 40 KT AND COASTAL OBSERVATIONS ARE SHOWING SUSTAINED WINDS TO 30 KT. THE PERSISTENCE OF THIS EVENT HAS GENERATED A LONG PLUME OF 12 TO 18 FT SEAS...WITH SEAS TO AT LEAST 8 FT REACHING AS FAR AS 115W AND MIXING WITH LONGER PERIOD NW AND SW SWELL. THE PRESSURE GRADIENT IS EXPECTED TO GRADUALLY RELAX LATER TODAY...ALLOWING WINDS TO DIMINISH BELOW GALE FORCE EARLY WED MORNING...THEN TO 20-25 KT BY WED AFTERNOON. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A WEAK MONSOON TROUGH EXTENDS FROM 009N85W TO 06N90W TO 05N95W. THE ITCZ REACHES FROM 05N95W TO 06N100W TO 03N115W TO 04N135W TO 02N138W TO 03N140W. SCATTERED MODERATE CONVECTION IS NOTED WITHIN 90 NM N OF AXIS BETWEEN 95W AND 105W. ...DISCUSSION... N OF 15N W OF 120W...A SHARP UPPER TROUGH REACHES FROM N CENTRAL MEXICO SOUTHWESTWARD TO WELL WEST OF THE AREA. AN UPPER IMPULSE IS MOVING SOUTHEAST ALONG 120W AND WILL BECOME CUT OFF FROM THE MAIN FLOW THROUGH LATE TODAY. THE UPPER TROUGH HAS BEEN SUPPORTING A SURFACE TROUGH RESIDENT OVER THE GULF OF CALIFORNIA REGION...RESULTING IN STRONG NW WINDS ALONG THE LENGTH OF THE GULF. AN 08 UTC OSCAT PASS INDICATED THESE WINDS ONGOING OVER THE CENTRAL GULF WITH GENERALLY 15 TO 20 KT NW WINDS ELSEWHERE OVER THE CENTRAL AND SOUTHERN GULF AREAS. THE GRADIENT WILL WEAKEN THROUGH TODAY AS THE UPPER FEATURE BECOMES CUT OFF AND WEAKENS. MEANWHILE LONG PERIOD NW SWELL WILL CONTINUE TO ADVANCE ALONG THE WEST COAST OF THE BAJA CALIFORNIA PENINSULA WITH WAVE HEIGHTS AS HIGH AS 13 FT OFF GUADALUPE ISLAND TODAY AND SEAS TO TO 9 FT REACHING THE REVILLAGIGEDO ISLANDS BY TONIGHT AND THE AREA BETWEEN LOS CABOS AND CABO CORRIENTES SOUTH OF THE ENTRANCE TO THE GULF OF CALIFORNIA BY EARLY WED. THE SWELL WILL SUBSIDE TO 8 TO 9 FT ACROSS THE REGION THROUGH THU. LOOKING AHEAD... GLOBAL MODELS ARE IN GOOD AGREEMENT SHOWING ANOTHER UPPER TROUGH DIGGING THROUGH THE SOUTHWEST UNITED STATES AND NW MEXICO FRI INTO SAT. AN ASSOCIATED COLD FRONT WILL MOVE INTO THE REGION BRINGING STRONG NW WINDS TO THE WEST COAST OF BAJA CALIFORNIA AND THE GULF OF CALIFORNIA FRI AND SAT WITH ANOTHER ROUND OF NW SWELL. S OF 15N W OF 110W...STRONG GAP WINDS CONTINUE TO PULSE THROUGH GULF OF PAPAGAYO MAINLY DURING OVERNIGHT HOURS WITH THE AID OF NOCTURNAL DRAINAGE FLOW. SEAS WILL OCCASIONALLY BUILD TO 8 FT DURING THE PERIOD OF STRONGEST WINDS. FARTHER WEST...RECENT ALTIMETER SATELLITE DATA CONFIRM A LARGE AREA OF SEAS OF 8 TO 12 FT S OF 14N W OF 90W CONSISTENTING OF NE SWELL RELATED TO THE TEHUANTEPEC GALE EVENT MIXED WITH LONGER PERIOD COMPONENTS OF NW AND SW SWELL. THE NE COMPONENT WILL TAPER OFF THROUGH THE NEXT 48 HOURS WITH THE NW SWELL BECOMING DOMINANT. MEANWHILE MAINLY OVERNIGHT SCATTERED MODERATE CONVECTION PERSISTS OFF COLOMBIA. ELSEWHERE...A 1025 MB SURFACE HIGH IS CENTERED NEAR 31N133W. RECENT SCATTEROMETER DATA ALONG WITH TOGA BUOY OBSERVATIONS INDICATED FRESH TO OCCASIONALLY STRONG WINDS IN THE DEEP TROPICS...ENHANCED IN PART BY A SURFACE TROUGH FROM 09N132W TO 03N135W. THE TRADE WIND CONVERGENCE IN THE LOWER LEVELS ALONG WITH GOOD UPPER EXHAUST ON THE SOUTHERN END OF A BROAD UPPER TROUGH IS ALLOWING SCATTERED MODERATE CONVECTION ROUGHLY S OF 10N W OF 120W. MEANWHILE A LARGE AREA OF LONG PERIOD NW SWELL WITH SEAS GREATER THAN 8 FT COVERS MOST OF THE REGION. RECENT ALTIMETER SATELLITE PASSES SHOWED 12-15 FT SEAS W OF 120W. WAVE HEIGHTS ARE FORECAST TO GRADUALLY SUBSIDE DURING THE NEXT 24-48 HOURS. $$ CHRISTENSEN