000 AXPZ20 KNHC 160327 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC FRI NOV 16 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0300 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 08N78W TO 09N84W TO 06N95W THEN ITCZ AXIS CONTINUES TO 08N118W TO 09N130W TO BEYOND 09N140W. ISOLATED TO SCATTERED MODERATE CONVECTION IS NOTED WITHIN 90 NM N OF AXIS BETWEEN 105W AND 118W...AND BETWEEN 133W AND 136W. ...DISCUSSION... ALOFT...A TROUGH/RIDGE PATTERN DOMINATES THE FORECAST REGION. AN UPPER ANTICYCLONE CENTERED NEAR 16N107W EXTENDS A RIDGE TO THE N ACROSS BAJA CALIFORNIA AND NW MEXICO INTO THE SW CONUS. THE ANTICYCLONIC FLOW COVERS ROUGHLY THE AREA BETWEEN 100W AND 120W. BROAD UPPER LEVEL CYCLONE TO THE S OF ANTICYCLONE IS NOW LOCATED NEAR 04N110W. THESE TWO UPPER LEVEL FEATURES HAVE MOVED IN TANDEM DURING THE PAST FEW DAYS. A DEEP LAYERED CYCLONE IS SPINNING NEAR 34N131W. AN UPPER LEVEL TROUGH EXTENDS FROM THE CYCLONE TO BEYOND 22N140W. STRONG WLY FLOW IS NOTED AROUND THE BASE OF THE TROUGH WITH A WIND MAXIMA OF 90-110 KT TO THE SE OF THE CYCLONE ASSOCIATED WITH A SUBTROPICAL JET. TO THE E OF THE ANTICYCLONE...ANOTHER UPPER LEVEL TROUGH ENTERS THE AREA FROM THE NW CARIBBEAN THROUGH NORTHERN CENTRAL AMERICA TO NEAR 09N96W. SWLY FLOW AHEAD OF THE TROUGH COVERS THE REGION N OF 5N WHERE SOME MID/UPPER LEVEL MOISTURE IS OBSERVED ON WATER VAPOR IMAGERY. AT THE SURFACE...A 1019 MB HIGH PRESSURE IS CENTERED NEAR 29N119W. A 1004 MB LOW PRESSURE IS LOCATED N OF THE AREA NEAR 33N132W. THE ASSOCIATED COLD FRONT ENTERS THE FORECAST REGION NEAR 30N126W THEN CONTINUES S AND SW TO 20N132W. THE COLD FRONT IS FORECAST TO MERGE WITH A SECONDARY FRONT CURRENTLY MOVING ACROSS THE FAR NW PORTION OF THE AREA IN ABOUT 24 HOURS. THE MERGED FRONT WILL REACH A POSITION FROM 30N128W TO 24N137W FRI EVENING AND WILL DISSIPATE OVER THE FORECAST WATERS BY SAT EVENING. THE LOW PRES IS FORECAST TO MOVE NE AND AWAY FROM THE AREA WITH HIGH PRES BUILDING AGAIN ACROSS THE N WATERS BY LATE SAT BRINGING SOME INCREASE IN THE TRADE WINDS. THE ABOVE MENTIONED DEEP LAYERED CYCLONE SUPPORTS THE SURFACE LOW AND THE FRONTS. LONG PERIOD NW SWELL ASSOCIATED WITH THE LOW PRESSURE SYSTEM IS PUSHING ACROSS THE NW PART OF THE REGION WITH COMBINED SEAS TO 13 FT. THIS SWELL EVENT WILL PROPAGATE S AND E ACROSS THE REGIONAL WATERS OVER THE NEXT COUPLE OF DAYS WITH SEAS SUBSIDING TO 8-9 FT W OF LINE FROM 30N124W TO 20N130W TO 12N140W BY SAT EVENING. A COUPLE OF WEAK TROUGHS ARE EMBEDDED IN THE ITCZ. ONE EXTENDS FROM 11N117W TO 07N120W AND THE OTHER IS FROM 14N126W TO 08N129W. SCATTERED MODERATE CONVECTION IS NEAR THE NORTHERN END OF THE EASTERNMOST TROUGH. THE 2032 UTC OSCAT PASS REVELED THE WIND SHIFT ASSOCIATED WITH THE WESTERNMOST TROUGH...WHICH WILL CONTINUE TO MOVE WWD. GAP WINDS... THE 1852 UTC OSCAT PASS PROVIDED OBSERVATIONS OF 30 KT WINDS ACROSS THE GULF OF TEHUANTEPEC. SHIP CALL SIGN DAXJ AND A JASON PASS INDICATED THE PRESENCE OF 12-13 FT SEAS DOWNSTREAM OF THE GULF TO NEAR 12.5N95W. WINDS WILL DIMINISH TO JUST BELOW GALE FORCE DURING THE AFTERNOON HOURS FRI AND SAT. HOWEVER...DURING THE OVERNIGHT AND EARLY MORNING HOURS...THE ADDED COMPONENT OF NOCTURNAL DRAINAGE FLOW WILL PUSH WINDS BACK ABOVE GALE FORCE IN THE GULF OF TEHUANTEPEC. SO...THE GALE WARNING HAS BEEN EXTENDED THROUGH SAT EVENING TO ACCOUNT FOR THIS PULSING OF WINDS TO GALE FORCE. FRESH TO STRONG WINDS OVER THE SW CARIBBEAN FUNNELING THROUGH THE GAP IN TOPOGRAPHY OVER NICARAGUA ARE PRODUCING FRESH TO STRONG WINDS OVER THE GULF OF PAPAGAYO. THESE WINDS WILL CONTINUE THROUGH THE FORECAST PERIOD...PEAKING DURING THE OVERNIGHT AND EARLY MORNING HOURS WITH THE AID OF THE NOCTURNAL DRAINAGE FLOW. $$ GR