000 AXPZ20 KNHC 131533 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC THU DEC 13 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS ALONG 07N78W TO 08N86W TO 06N98W. THE INTERTROPICAL CONVERGENCE ZONE AXIS EXTENDS FROM 06N98W TO WEAK LOW PRES NEAR 10N109W 1011 MB TO 07N124W TO 09N138W. SCATTERED MODERATE AND ISOLATED STRONG CONVECTION IS WITHIN 120-180 NM S OF A LINE FROM 07N78W TO 05N82W. SIMILAR CONVECTION IS WITHIN 75 NM S OF THE MONSOON TROUGH BETWEEN 89W AND 92W. NO CONVECTION IS NOTED WITH THE LOW. ...DISCUSSION... E OF 110W... A GALE WARNING REMAINS IN EFFECT OVER THE GULF OF TEHUANTEPEC THROUGH 18 UTC TODAY AS COOLER AND DENSER AIR N OF THE AREA IN THE GULF OF MEXICO BEHIND A FRONTAL BOUNDARY CONTINUES TO SEEP THROUGH THE GAP INTO THE NE PACIFIC. 1024 MB HIGH PRES OVER EASTERN MEXICO NEAR 23N99W WILL WEAKEN SLIGHTLY THIS AFTERNOON WHILE SHIFTING E ALLOWING FOR MORE E TO SE FLOW OVER THE SW GULF OF MEXICO. THIS WILL ALLOW FOR THE GALE FORCE WINDS TO DIMINISH BELOW WARNING LEVEL. WINDS WILL STILL REMAIN FRESH TO STRONG... ESPECIALLY THU NIGHT INTO FRI MORNING...BEFORE DIMINISHING FURTHER FRI AFTERNOON AND TO 20 KT OR LESS BY FRI EVENING. FRESH TO STRONG WINDS WILL CONTINUE TO PULSE IN AND DOWNWIND OF THE GULF OF PAPAGAYO WITH COINCIDENT SEAS OF 8 TO 9 FT...MAINLY DURING THE LATE NIGHT AND EARLY MORNING HOURS. CONDITIONS WILL DIMINISH TO 20 KT OR LESS BY FRI AFTERNOON. SPORADIC CONVECTION IS FLARING ALONG THE MONSOON TROUGH E OF 92W...AND ESPECIALLY IN THE GULF OF PAPAGAYO AND W OF THE COAST OF COLOMBIA DUE IN PART TO CONVERGENT NORTHERLY FLOW ACROSS THE ISTHMUS OF PANAMA...AND THE NE FLOW IN THE GULF OF PAPAGAYO. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE ACTIVE ROUGHLY WITHIN 120-180 NM EITHER SIDE OF A LINE FROM W OF 110W NEAR 12N130W TO NEAR PUERTO VALLARTA MEXICO. THIS IS DUE TO UPPER FORCING IN THE RIGHT REAR ENTRANCE REGION OF A SOUTHERN STREAM JET MAX ALOFT AND WILL GRADUALLY DISSIPATE THROUGH THE DAY. LOOKING AHEAD...GLOBAL MODELS SUGGEST COASTAL TROUGHING WEDGED BETWEEN THE SUBTROPICAL RIDGE TO THE WEST AND HIGH PRES OVER MEXICO TO THE EAST WHICH WILL ALLOW FRESH TO STRONG NW TO N BREEZES TO COMMENCE OFF CABO CORRIENTES N OF MANZANILLO BY LATE FRI THROUGH SAT MORNING. W OF 110W AND GULF OF CALIFORNIA... A LONG WAVE TROUGH EXTENDS FROM THE NORTHERN U.S. ROCKIES THROUGH CENTRAL CALIFORNIA TO 30N124W WITH A TERMINUS NEAR 25N140W. THIS UPPER FEATURE IS SUPPORTING A COLD FRONT AT THE SURFACE EXTENDING FROM SOUTHERN CALIFORNIA NEAR ORANGE COUNTY TO 24N127W THEN DISSIPATING TO 20N140W. STRONG 1034 MB SURFACE HIGH PRES IS CENTERED NEAR 35N150W...AND IS CONTRIBUTING TO A LARGE SWATH OF FRESH TO STRONG NW TO N BREEZES SWEEPING OVER MUCH OF THE NE PACIFIC N OF 32N E OF 135W AS NOTED BY SHIP OBSERVATIONS AND BY OVERNIGHT SCATTEROMETER DATA. THESE WINDS ARE PENETRATING THE DISCUSSION AREA N OF THE FRONT TO 28N AND W OF 128W WITH SEAS ESTIMATED TO BE NEAR 11 FT IN NORTHERLY SWELL. A 1004 MB SURFACE LOW NEAR 40N117W OVER CENTRAL NEVADA WILL PIVOT EASTWARD INTO UTAH WITH THE UPPER TROUGH THROUGH TONIGHT ALLOWING FOR THE TRAILING SURFACE COLD FRONT TO SHIFT SE... REACHING A POSITION FROM NORTHERN BAJA NEAR 30N115W TO 25N120W TO 22N130W BY FRI MORNING. THIS WILL DELIVER FRESH TO STRONG MAINLY WEST BREEZES TO THE AREA N OF 25N E OF 120W TO THE BAJA COAST. SOUTHERLY WINDS PRECEDING THE FRONT HAVE ALREADY LIKELY INCREASED TO FRESH TO STRONG IN THE FAR NORTHERN GULF OF CALIFORNIA. GLOBAL MODELS ARE CONSISTENTLY SHOWING ANOTHER MID LEVEL DISTURBANCE PUSHING SE INTO THE BASE OF THE UPPER TROUGH DURING THE NEXT 24 TO 48 HOURS WHICH WILL MAINTAIN THESE WINDS ACROSS THE BAJA COAST AND THE NORTHERN GULF OF CALIFORNIA THROUGH FRI AFTERNOON. WAVEWATCH AND ECWAVE MODEL GUIDANCE INDICATE ANOTHER SET OF NW TO N SWELL WITH SEAS OF 8 TO 10 FT ARRIVING W OF THE PENINSULA BY SAT MORNING. MEANWHILE THE NORTHERLY WINDS N OF THE FRONT AND W OF 120W WILL LARGELY DIMINISH LATER TODAY AS HIGH PRES BUILDS INTO THE AREA AND THE UPPER DYNAMICS SHIFT E. FRESH NW TO N SWELL OF 8 TO 10 FT WILL PERSIST ELSEWHERE OVER THE WATERS N OF 22N AND W OF THE FRONT INTO FRI MORNING. AS THE HIGH BUILDS INTO THE AREA BEHIND THE FRONT...TRADE WINDS WILL START TO INCREASE OVER THE W CENTRAL WATERS FROM ROUGHLY 12N TO 22N W OF 133W BY FRI MORNING WITH SEAS TO 10 FT MAINLY IN WIND WAVES. PRECIPITABLE WATER VALUES REMAIN HIGH ALONG THE ITCZ BETWEEN 08N AND 12N...AND LOW LEVEL CONVERGENCE FROM THE INCREASED TRADES WILL PRODUCE LINES OF MODERATE TO STRONG CONVECTION NEAR THE ITCZ THROUGH THE END OF THE WEEK INTO THE WEEKEND. $$ LEWITSKY