000 AXPZ20 KNHC 190337 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC THU DEC 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...SPECIAL FEATURE... GULF OF TEHUANTEPEC...THE ASCAT PASS FROM YESTERDAY CLEARLY 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 16N94.5W 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 BY DAYBREAK 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 THE 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 07N90W TO 07N98W...WHERE IT TRANSITIONS TO THE ITCZ TO 07N110W TO 09N120W TO 10N132W TO 07N140W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS WITHIN 180 NM S OF ITCZ BETWEEN 118W-121W...AND WITHIN 120 NM S OF THE ITCZ BETWEEN 128W -130W. SCATTERED MODERATE CONVECTION IS WITHIN 30 NM OF THE ITCZ BETWEEN 134W-138W. ...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 SEWD JUST N OF THE AREA ALONG 32N33N. A JET STREAM BRANCH BETWEEN IT AND THE ANTICYCLONIC RIDGE CREST 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 ANTICYCLONIC FLOW AND CONTRIBUTING TO THE ATMOSPHERIC MOISTURE DESCRIBED ABOVE. THIS MOISTURE IS SEEN IN THE FORM OF THE SCATTERED TO BROKEN HIGH CLOUDS. THE MOISTURE...HOWEVER...ERODES IN THE DRY AIR ONCE IT REACHES NEAR 110W. SURFACE... A SURFACE RIDGE ANCHORED BY A 1034 MB ANTICYCLONE CENTER NW OF THE AREA NEAR 38N144W EXTENDS SEWD THROUGH 32N137W AND TO NEAR 23N125W. ASCAT DATA FROM YESTERDAY AFTERNOON REVEALED FRESH NE TRADES S OF THE RIDGE AND N OF THE ITCZ W OF 128W. 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 ABOUT 9 FT WITHIN THE AREA OF ENHANCED TRADES. BY THU AFTERNOON...NE WINDS OF 20-25 KT ARE EXPECTED FROM 10N TO 20N W OF 133W WITH SEAS TO 9 FT. THESE WINDS SHOULD THEN DIMINISH TO 20 KT OR LESS N OF 10N W OF 135W BY FRI EVENING. WINDS 20 KT OR LESS ARE ALSO EXPECTED N OF 08N BETWEEN 127W AND 135W BY FRI EVENING WITH SEAS 10 TO 14 FT IN N TO NE SWELLS. THE UPPER TROUGH DESCRIBED ABOVE UNDER ALOFT WILL DRIVE A COLD FRONT SEWD TO ALONG A POSITION FROM NEAR 32N116W TO 26N130W BY THU EVENING. THE PARENT LOW PRES WILL BE NEAR 32N113W 1004 MB WITH THE DISSIPATING COLD FRONT FROM LOW TO 30N114W TO 26N115W TO 23N127W BY FRI AFTERNOON. NW TO N WINDS OF 20-25 KT ARE EXPECTED N OF THE FRONT THU EVENING WITH SEAS 8-12 FT...WITH HIGHER SEAS OF 10-14 FT PRIMARILY IN NW SWELLS N OF 28N. BY 36 HRS...THE COLD FRONT IS FORECAST TO EXTEND FROM 32N113W TO 24N124W TO 25N130W WITH NLY WINDS OF 20-25 KT N OF THE FRONT. SEAS OF 10-15 FT IN NW-N SWELLS ARE FORECAST BEHIND THE FRONT WITH MUCH HIGHER SEAS OF 12-17 FT N OF 27N BETWEEN 122W-127W. BY 48 HRS...THE COLD FRONT IS FORECAST TO BE DISSIPATING FROM 32N112W TO 23N127W. WINDS N OF THE FRONT WILL DIMINISH TO 20 KT OR LESS AT THAT TIME WITH SEAS 10-16 FT IN NW-N SWELLS. GULF OF PAPAGAYO...WINDS WILL INCREASE TO 20-25 KT IN ABOUT 6 HRS...THEN DIMINISH TO 15-20 KT THU NIGHT. WINDS THEN INCREASE AGAIN TO 20-25 KT LATE THU NIGHT INTO EARLY FRI MORNING AND DIMINISH TO 15-20 KT FRI IN THE AFTERNOON. NE SWELLS PROPAGATING SW FROM THE GULF OF PAPAGAYO WILL MIX WITH SW SWELLS WITHIN 60 NM OF A LINE FROM 09N90W TO 08N94W TO 07N98W IN 24 HRS WITH SEAS TO 9 FT. BY FRI AFTERNOON...SEAS ARE FORECAST TO BE LESS THAN 8 FT IN THE GULF...AND IN THE VICINITY OF THE GULF. GULF OF CALIFORNIA...WINDS WILL INCREASE TO 20-25 KT OVER THE FAR NRN GULF EARLY THU EVENING THEN DIMINISH TO 20 KT FRI MORNING. $$ AGUIRRE