000 AXPZ20 KNHC 310346 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SAT JAN 31 2009 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0315 UTC. ...ITCZ... ITCZ AXIS IS CENTERED ALONG 5N78W 5N90W 4N103W 3N115W 4N127W 3N140W. NO SIGNIFICANT CONVECTION IS NOTED. ...DISCUSSION... THE UPPER LEVEL FLOW PATTERN HAS BECOME MAINLY ZONAL OVER MUCH OF THE NRN PORTION OF THE AREA N OF 17N E OF ABOUT 127W IN THE WAKE OF A MID/UPPER LEVEL TROUGH THAT HAS PUSHED FURTHER INLAND THE SW U.S. DURING THE PAST FEW HOURS. A JET STREAM BRANCH WITH MAXIMUM WINDS OF 60-90 KT ENTERS THE AREA THROUGH 19N140W... AND CONTINUES TO 22N130W THEN E TO 22N120W AND ACROSS SRN BAJA CALIFORNIA INTO WRN MEXICO. THE JET CONTINUES TO ADVECT SCATTERED TO BROKEN HIGH LEVEL CLOUDS FROM THE DEEP CENTRAL TROPICAL PACIFIC REGION ENE TO NEAR 120W. A MID/UPPER LEVEL RIDGE AXIS EXTENDS FROM 20N130W TO 25N132W TO N OF THE AREA NEAR 33N137W. THIS RIDGE PRECEDES A LONGWAVE TROUGH W OF THE AREA...BUT IS GRADUALLY TRANSLATING EWD AND AMPLIFYING SOME AS THE TROUGH ALSO ADVANCES E. IT IS FORECAST TO MOVE THROUGH THE NW PORTION ON SAT AND SUN FOLLOWED BY ANOTHER AREA OF MID/UPPER LEVEL RIDGING. A 1033 MB HIGH IS CENTERED WELL N OF THE AREA NEAR 39N135W WITH A RIDGE EXTENDING S THROUGH 32N132W TO 26N123W TO 21N110W. THE SURFACE COLD FRONT ASSOCIATED WITH ABOVE UPPER LEVEL TROUGH IS FORECAST TO STAY N OF THE AREA THROUGH SAT. UPPER LEVEL CLOUDS CONTINUE TO BE CONCENTRATED OVER THE WRN SECTION OF THE AREA FROM 15N-26N W OF 134W WITH POSSIBLE WIDELY SCATTERED SHOWERS UNDERNEATH THEM AS THE UPPER LEVEL ENVIRONMENT BECOMES MORE DIFFLUENT AS THE UPPER FLOW PATTERN AHEAD OF TROUGH RESPONSES TO THE AMPLIFICATION OF THE MID/UPPER LEVEL RIDGE. ADDITIONAL LIFT TO THIS ACTIVITY WILL BE PROVIDED BY THE JET STREAM MENTIONED ABOVE. A MID/UPPER LEVEL TROUGH EXTENDS FROM 16N128W SE TO 8N124W TO NEAR 2N118W. TO THE E OF THE TROUGH...AS IN PREVIOUS DAYS... BROAD MID/UPPER LEVEL RIDGING DOMINATES THE AREA WITH AN ASSOCIATED NEARLY STATIONARY ANTICYCLONE NEAR 6N95W. THIS PATTERN CONTINUES TO RESULT IN MODERATE TO STRONG SUBSIDENCE WITH VERY DRY STABLE AIR E OF ABOUT 120W WHERE...WITH THE EXCEPTION OF SCATTERED LOW CLOUDS WITH ISOLATED SHOWERS MOVING W...SKIES ARE MOSTLY CLEAR. THESE CONDITIONS ARE EXPECTED TO LAST OVER THE NEXT 48 HOURS AS MID/UPPER RIDGING HOLDS ACROSS THIS AREA. PERSISTENT NE TRADE WINDS IN THE 20-25 KT RANGE FROM 5N TO 22N W OF 122W DUE TO A TIGHT PRES GRADIENT CREATED BY THE RIDGE MENTIONED IN THE FIRST PARAGRAPH AND LOWER PRES OVER THE EQUATORIAL PACIFIC ZONE ARE FORECAST TO TRANSLATE W OF THE AREA WITH A SWATH OF NE-E 20 KT WINDS REMAINING OVER A PORTION OF THE WRN PART OF THE AREA WITHIN THE NEXT 48 HOURS AS THE THE HIGH CENTER NEAR 39N135W SLIDES ESE WHILE WEAKENING AND SHIFTS THE RIDGE AXIS TO W OF 140W. SEAS HERE...HOWEVER...WILL CONTINUE IN THE 8-10 FT DRIVEN BY MAINLY A NE SWELL WITH THE HIGHEST OF THESE JUST ALONG 140W IN 48 HOURS. GAP WINDS... GULF OF PAPAGAYO NE 20 KT WINDS ARE FORECAST TO CHANGE LITTLE THROUGH THE WEEKEND. A GULF OF TEHUANTEPEC STORM EVENT IS PRESENTLY GETTING UNDER WAY AS STRONG HIGH PRES BUILDS SWD INTO THE FAR WRN GULF OF MEXICO AND ALONG THE ERN SLOPES OF THE SIERRA MADRE MOUNTAINS OF MEXICO IN THE WAKE OF A COLD FRONT CURRENTLY PRESSING SWD OVER SE MEXICO AND THE YUCATAN PENINSULA. WARM SSTS N THE GULF BASED ON LATEST SST ANALYSIS OF THE E PAC SHOULD PROVIDE FOR VERY GOOD INSTABILITY ALLOWING FOR THESE STRONG WINDS TO MIX DOWN TO THE SURFACE. A RECENT QUIKSCAT PASS FROM 0042 UTC SHOWED UP TO 40 KT OF N WINDS WITHIN ABOUT 60 NM OF THE TEHUANTEPEC COAST. MODEL RUNS OVER THE PAST FEW DAYS HAVE BEEN VERY CONSISTENT IN SUGGESTING THAT THIS EVENT WILL OCCUR AS A SHORT-LIVED STORM EVENT BEFORE TAPERING DOWN TO A GALE EVENT IN ABOUT 18 HOURS...AND SUBSIDING TO BELOW GALE FORCE WINDS EARLY SUN MORNING AS HIGH PRES OVER THE FAR WRN GULF AND MEXICO WEAKENS SUBSTANTIALLY. RESIDUAL NE SWELLS FROM THIS EVENT WILL SPREAD SW TO NEAR 102W THROUGH SUN MORNING BEFORE DIMINISHING BY LATE AFTERNOON. $$ AGUIRRE