000 AXPZ20 KNHC 290349 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN JAN 29 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 0230 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 07N74W TO 02N79W TO 06N84W TO 04N97W...WHERE IT TRANSITIONS TO ITCZ AXIS...CONTINUING ON TO 06N107W TO 06.5N124W TO BEYOND 04N140W. ISOLATED TO SCATTERED MODERATE ISOLATED STRONG FROM 08.5N TO 14N BETWEEN 95W AND 119W. ...DISCUSSION... THE UPPER LEVEL PATTERN ACROSS THE AREA HAS BECOME COMPLEX TODAY AS A PATTERN SHIFT IS UNDERWAY. A STAGNANT TROUGH-RIDGE-TROUGH PATTERN HAS PREVAILED NORTH OF 20N THROUGHOUT THE PAST WEEK. HOWEVER...THE WEAK WESTERN-MOST TROUGH ALONG ABOUT 140W OF THE PAST MANY DAYS HAS OPENED UP AND IS BEING PULLED NORTHWARD... WITH N PORTIONS EXPECTED TO BECOME ENTRAINED INTO A SHARP AND ENERGETIC MIDDLE TO UPPER LEVEL LONG WAVE TROUGH CROSSING 140W THIS EVENING. THE DOWNSTREAM RIDGE...CENTERED ON AN ANTICYCLONE NEAR 31N125W...CONTINUES TO SHIFT E-SE AS THE N PORTION OF THE LONG WAVE TROUGH IS BEGINNING TO FEEL THE RIDGE AND LIFT NE... WHILE BROAD TROUGHING ACROSS THE EASTERN TWO-THIRDS OF N AMERICA EXTENDS A SINKING TROUGH SW ACROSS NEW MEXICO TO FAR NW MEXICO NEAR 28N110W...WHERE SATELLITE IMAGERY SUGGESTS A MIDDLE LEVEL CYCLONE...WITH TROUGH CONTINUING TO 23N120W. UPPER LEVEL RIDGING ACROSS THE TROPICS TO THE S OF THIS AREA THE PAST 48 HOURS HAS BECOME ELONGATED SE TO NW FROM NEAR 12N110W TO 26N130W. THE LONG WAVE TROUGH APPROACHING FROM THE W IS THE INSTIGATOR IN THIS UPCOMING PATTERN CHANGE...WITH N PORTIONS OF THE TROUGH EXPECTED TO MOVE E INTO N AMERICA BY SUN NIGHT AND ACT TO FLATTEN THE CURRENT RIDGE TO ITS E...WHILE THE SOUTHERN PORTION OF THE LONG WAVE TROUGH LINGERS JUST W OF THE AREA AND EVOLVES INTO A CUT OFF LOW SOUTHEAST OF THE BIG ISLAND OF HAWAII. AT LOWER LEVELS...A SURFACE HIGH PRES RIDGE COVERS THE AREA N OF 20N W OF 124W. A SHRINKING AREA TO FRESH TRADES HAS BEEN OBSERVED DURING THE PAST 36 HOURS...WITH RECENT SCATTEROMETER PASSES SUGGESTING NE TRADES AT 20 KT ARE NOW OCCURRING ONLY FROM 07N TO 12N W OF 134W. N TO NE WINDS NEAR 20 KT ARE OBSERVED N OF 24.5N BETWEEN 117W AND 129W. COMBINED SEAS ACROSS THESE AREAS ARE RUNNING 8 TO 9 FT IN MIXED SWELL. OTHERWISE MODERATE TO LARGE NWLY SWELLS ARE ACROSS MUCH OF THE AREA N OF 23N W OF 114W. AS THE LONG WAVE TROUGH SWEEPS ACROSS N PORTIONS OF THE AREA DURING THE NEXT 48 HOURS...THE CURRENT SURFACE RIDGE WILL WEAKEN AND REORGANIZE TO THE SW...SHIFTING THE AREA OF FRESH TRADES THAT IS TYPICALLY FOUND N OF THE ITCZ INTO THE CENTRAL PACIFIC AND JUST W OF THE LOCAL AREA. STRONG HIGH PRES ACROSS THE GREAT BASIN EXTENDS S INTO THE DESERT SW OF THE U.S. AND HAS INDUCED A NWLY WIND SURGE OF 20-25 KT THROUGH THE NORTHERN TWO THIRDS OF THE GULF OF CALIFORNIA. THESE CONDITIONS WILL PREVAIL OVERNIGHT AND RAISE SEAS TO AROUND 8 FT THROUGH THE CENTRAL GULF BEFORE MORNING. WINDS AND SEAS ARE THEN EXPECTED TO SLOWLY DIMINISH TO LESS THAN 20 KT BY MON MORNING. THE PRES GRADIENT OVER SOUTHERN MEXICO HAS RELAXED AND WINDS DECREASED TO BELOW 20 KT THROUGH THE GULF OF TEHUANTEPEC DURING THE PAST AFTERNOON. HOWEVER ANOTHER REINFORCING WEAK COLD FRONT IS EXPECTED TO MOVE THROUGH THE GULF OF MEXICO TONIGHT AND SUNDAY WITH STRONG HIGH PRES BUILDING BEHIND THE FRONT. THIS WILL ONCE AGAIN TIGHTEN THE PRES GRADIENT ACROSS SOUTHERN MEXICO RESULTING IN GALE FORCE WINDS THROUGH THE GULF OF TEHUANTEPEC BEGINNING LATE TONIGHT THROUGH EARLY SUN MORNING. ELY GAP WINDS TO 20 KT CONTINUE TO BLOW THROUGH THE GULF OF PAPAGAYO AND ARE EXPECTED TO PERSIST THROUGH THE WEEKEND... EXPANDING SOMEWHAT NORTH TO SOUTH OVERNIGHT...AS WELL AS DOWNSTREAM TO NEAR 90W BY SUNDAY AFTERNOON. THIS WILL RAISE SEAS TO NEAR 8 FT BY SUNDAY AFTERNOON. $$ STRIPLING