000 AXPZ20 KNHC 182205 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC WED DEC 18 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...SPECIAL FEATURE... GULF OF TEHUANTEPEC...THE 1620 UTC ASCAT PASS CLERLY DEPICTED A SWATH OF N TO NE GALE FORCE WINDS OF 30-35 KT WITHIN THROUGH THE GULF WITHIN ABOUT 30-45 NM OF A LINE FROM 16N95W TO NEAR 14N96W. WITH THE CULPRIT TIGHT PRES GRADIENT OVER SOUTHEASTERN MEXICO EXPECTED TO SLACKEN THROUGH THE NEXT 12-18 HRS...THESE WINDS WILL RESPOND BY DIMINISHING TO 20-30 KT TONIGHT...AND INTO EARLY THU AND TO 15-20 KT BY THU AFTERNOON BEFORE DIMINISHING FURTHER TO 10-15 KT THU EVENING AND FRI. SEAS OF 10-14 FT IN THE GULF WILL SUBSIDE TO 8-10 FT BY EARLY THU...AND TO 9 FT IN MIXED SWELL BY THU AFTERNOON. SEAS DOWNSTREAM FROM THE GULF WILL ALSO SUBSIDE TO AROUND 9 FT IN MIXED SWELL WITHIN WITHIN AREA BOUNDED BY A LINE FROM 15N95W TO 07N98W TO 10N107W TO 15N95W BY THU AFTERNOON. BY THU EVENING...SEAS ARE EXPECTED TO BE BELOW 8 FT IN THE GULF WITH SEAS LESS THAN 8 FT. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM THE COLOMBIAN COAST AT 07N78W TO 07N86W TO 07N100W....WHERE LOW LEVEL WINDS SUGGEST IT TRANSITIONS TO THE ITCZ TO 07N111W TO 08N130W TO 07N140W. SCATTERED/MODERATE ISOLATED STRONG IS WITHIN 180 NM S OF THE OF ITCZ BETWEEN 119W-124W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM N OF ITCZ BETWEEN 127W-132W...AND ALSO WITHIN 90 NM S OF MONSOON TROUGH E OF 81W. ...DISCUSSION... ALOFT... AN ANTICYCLONE IS SEEN NEAR 12N117W WITH ITS ASSOCIATED BROAD ANTICYCLONIC ENVELOP COVERING THE AREA FROM 11N TO 26N W OF 109W. A NARROW UPPER TROUGH IS E OF THE ANTICYCLONIC FLOW ALONG 108W WITH AN ASSOCIATED SMALL CYCLONIC CIRCULATION AT 13N108W. A SMALL ANTICYCLONE IS E OF THIS TROUGH NEAR 12N99W...WHILE A CYCLONIC CIRCULATION IS TO ITS SE NEAR 06N95W. OVER THE NRN PORTION OF THE AREA...AN UPPER TROUGH WITH SHORTWAVE ENERGY MOVING THROUGH IT IS RAPIDLY SWEEPING SED JUST N OF THE AREA ALONG 32N33N. A JET STREAM BRANCH BETWEEN IT AND THE ANTICYCLONIC RIDGE ENEVLOP TO ITS S IS ACCOMPANIED BY MODERATE SW WINDS THAT ARE TRANSPORTING ABUNDANT BROKEN MID/HIGH CLOUDS NEWD BETWEEN 110W-122W AND FROM 11N-23N W OF 122W. DIFFLUENT FLOW SE OF THE ANTICYCLONE IS AIDING THE ACTIVE CONVECTION DESCRIBED ABOVE WITH THE ITCZ AXIS. SATELLITE WATER VAPOR IMAGERY SHOWS MOSTLY MODERATE SUBSIDENCE ELSEWHERE KEEPING GENERALLY DRY AND STABLE ATMOSPHERIC CONDITIONS...EXCEPT FOR W OF THE ANTICYCLONE WHERE SLY UPPER FLOW THERE IS ADVECTING THE DEBRIS MOISTURE N AND NE AROUND THE AFOREMENTIONED ANTICYLONIC FLOW AND CONTRIBUTING TO THE ATMOSPHERIC MOISTURE DESCRIBED ABOVE. THIS MOITURE IS SEEN IN THE FORM OF THE SCATTERDE TO BROKEN HIGH CLOUDS. THE MOSITURE...HOWEVER...ERODES IN THE DRY AIR ONCE IT REACHES NEAR 110W. THE UPPER TROUGH WILL PUSH A SURFACE COLD FRONT SEWD TO ALONG A POSTION FROM NEAR 31N118W TO 26N127W BY THU AFTERNOON. THE PARENT LOW PRES WILL BE NEAR 2N113W 1004 MB WITH THE DISSIPATING COLD FRONT FROM LOW TO 30N114W TO 26N115W TO 23N127W BY FRI AFTERNOON. SURFACE... A SURFACE RIDGE ANCHORED BY A 1038 MB ANTICYCLONE CENTER N OF THE AREA NEAR 38N138W EXTENDS SEWD THROUGH 32N137W AND TO NEAR 21N122W. ASCAT DATA FROM TUE AFTERNOON REVEALED FRESH NE TRADES S OF THE RIDGE AND N OF THE ITCZ W OF 120W. LONG PERIOD NW SWELLS ARE MIXING WITH THE NE TRADE WIND SWELL AND ALSO LONG PERIOD CROSS- EQUATORIAL SOUTHERLY SWELL...RESULTING IN COMBINED SEAS OF 7-10 FT WITHIN THE AREA OF ENHANCED TRADES. BY FRI...NW SWELLS WILL BE MIXING IN WITH NE SWELL TO PRODUCE SEAS OF 8-10 FT FROM 09N TO 21N W OF 130W. THE DEEPENING UPPER TROUGH DESCRIBED ABOVE UNDER ALOFT WILL MOST LIKELY PUSH A DRY COLD FRONT SEWD ACROSS THE VAST MAJORITY OF THE EASTERN AND N CENTRAL PACIFIC LATE THU AND THROUGH FRI. STRONG HIGH PRES BEHIND THE COLD FRONT WILL ALLOW FOR COLD AIR ADVECTION TO SETTLE IN OVER THE ERN PORTION OF THE AREA BY LATE FRI RESULTING IN GALE FORCE NW TO N WINDS ALONG THE COAST OF CENTRAL AND SOUTHERN CALIFORNIA THU AND FRI. THESE WIND CONDITIONS WILL GENERATE VERY LARGE SEAS OF 18-21 FT JUST N OF THE AREA E OF 126W BY LATE THU NIGHT...THEN SLOWLY SUBSIDE TO 15- 18 FT FRI. SEAS OF 10-16 FT ARE EXPECTED TO SPREAD SWD INTO THE AREA N OF 27N E OF 127W FRI. GULF OF PAPAGAYO...NE-E WINDS WILL PULSE AT 20-25 KT DURING MAX NOCTURNAL DRAINAGE PERIOD TONIGHT THROUGH THU NIGHT...THEN MAX AT 15-20 KT EARLY THU EVENING...AND INCREASE BACK UP TO 20-25 KT LATE THU NIGHT INTO EARLY FRI. NE SWELL PROPAGATING SW FROM THE GULF OF PAPAGAYO WILL MIX WITH NW SWELL FROM THE GULF OF TEHUANTEPEC EVENT AND CROSS-EQUATORIAL S SWELL...RESULTING IN COMBINED SEAS OF 6-8 FT AS FAR W AS 09N91W BY EARLY THU...THEN DIMINISH TO LESS THAN 8 FT LATE THU NIGHT. GULF OF CALIFORNIA...MODERATE TO FRESH NW WINDS WILL DIMINISH TO 5-10 KT WED AND BECOME SOUTHERLY WED NIGHT. WINDS WILL INCREASE TO 20-25 KT OVER THE NORTHERN GULF EARLY THU EVENING THEN DIMINISH BY FRI AFTERNOON. $$ AGUIRRE