000 AXPZ20 KNHC 171601 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC MON DEC 17 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... MONSOON TROUGH EXTENDS FROM 09.5N75W TO 06N79W TO 10N86W TO 06N109W...WHERE IT TRANSITIONS TO ITCZ AXIS...CONTINUING ON TO 07N116W TO 06N136W TO BEYOND 06N140W. ISOLATED TO SCATTERED MODERATE CONVECTION NOTED WITHIN 90 NM S OF TROUGH AXIS E OF 108W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 210 NM N OF ITCZ W OF 132W...AND FROM 10N TO 16N W OF 124W. ...DISCUSSION... THE SURFACE RIDGE EXTENDING ACROSS THE NORTHERN PART OF THE FORECAST AREA FOR THE PAST SEVERAL DAYS HAS WEAKENED SOMEWHAT...AS THE DEEP LAYERED RIDGE PERSISTING W TO E ACROSS THE CENTRAL ATLC HAS REORGANIZED AND IS NOW CENTERED FARTHER W NEAR 37N163W. THE PRESSURE GRADIENT BETWEEN THIS BROAD AND ELONGATED RIDGE AND LOWER PRESSURE IN THE VICINITY OF THE ITCZ IS MAINTAINING FRESH TO STRONG NE TO E TRADEWINDS FROM 07N TO 20N W OF 125W AND FROM 12N TO 17N BETWEEN 115W AND 125W...WHERE SEAS ARE RUNNING 8 TO 11 FT IN MIXED NE AND NW SWELL. THE RIDGE WILL WEAKEN SLIGHTLY OVER THE NEXT 24 HOURS...IN ADVANCE OF A STRONG COLD FRONT APPROACHING FROM THE NW...AND WILL REDUCE THE AREAL EXTENT OF FRESH TO STRONG TRADEWINDS OVER THE NEXT 24 HOURS...COVERING THE AREA FROM 12N TO 17N W OF 135W BY EARLY TUE. THE COLD FRONT TO MOVE INTO THE NW PART OF THE FORECAST AREA EARLY TUE WITH FRESH TO STRONG N TO NE WINDS BUILDING IMMEDIATELY BEHIND THE FRONT...AND REACH FROM NW PORTIONS OF MEXICO...ACROSS CENTRAL BAJA CALIFORNIA TO NEAR 19N140W BY WEDNESDAY MORNING. LARGE NW TO N SWELL WILL ALSO SPREAD INTO THE AREA WATERS WITH AND BEHIND THE FRONT...WITH SEAS AS HIGH AS 14 FT BY EARLY WED. HIGH PRESSURE BUILDING IN THE WAKE OF THE FRONT WILL ONCE AGAIN REESTABLISH OVER THE N PART OF THE AREA...WHICH WILL INCREASE THE AREAL COVERAGE OF FRESH TO STRONG TRADES BY LATE TUE/EARLY WED. ALTHOUGH THE SURFACE RIDGE HAS WEAKENED SLIGHTLY DURING THE PAST 24 HOURS...THE NOSE OF THE RIDGE CONTINUES TO EXTEND SE TO NEAR 21N110W. THIS IS COMBINING WITH A PERSISTENT TROUGH OF LOW PRESSURE ALONG THE W SLOPES OF THE SIERRA MADRES OCCIDENTALES... AND ANOTHER SURGE OF COLD AIR SPILLING INTO NE PORTIONS OVERNIGHT...TO PRODUCE A SURGE OF NW TO N WINDS 20-25 KT THROUGH ALL BUT N PORTIONS OF THE GULF OF CALIFORNIA...CONTINUING S THROUGH THE MOUTH OF THE GULF TO 17N. IN FACT...OVERNIGHT SCATTEROMETER PASSES SUGGESTED THAT AREAS OF SOLID 25 KT WINDS WITH GUSTS TO 30 KT WERE OCCURRING ACROSS S PORTIONS OF THE GULF. SEAS HAVE BUILT 6-9 FT ACROSS THESE SOUTHERN PORTIONS THIS MORNING. HOWEVER...THIS WIND SURGE IS EXPECTED TO BE SHORT LIVED...AND DIMINISH QUICKLY TO LESS THAN 20 KT THIS EVENING AS THE RIDGE WEAKENS FURTHER. WINDS AND SEAS WILL AGAIN INCREASE INSIDE THE GULF ON WED AS THE APPROACHING COLD FRONT MOVES SE THROUGH N PORTIONS OF THE PENINSULA. GAP WINDS... NO SIGNIFICANT GAP WINDS CURRENTLY PREVAIL ACROSS THE AREA. HOWEVER...THE STRONG COLD FRONT EXPECTED TO MOVE ACROSS THE AREA IN THE NEXT 48 HOURS WILL SHIFT RAPIDLY ACROSS THE GULF OF MEXICO ON THU. WINDS BEHIND THIS FRONT WILL FUNNEL THROUGH THE CHIVELA PASS INTO THE GULF OF TEHUANTEPEC WHICH WILL LEAD TO A STRONG GAP WIND EVENT. NORTHERLY GALES WILL START TO FUNNEL ACROSS AND DOWNWIND OF THE GULF OF TEHUANTEPEC BY EARLY THU NIGHT...WITH STORM FORCE WINDS POSSIBLE BY FRI MORNING. $$ STRIPLING