000 AXPZ20 KNHC 180328 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC FRI DEC 18 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 0130 UTC. ...ITCZ... THE ITCZ AXIS LIES ALONG A LINE FROM 05N77W TO 07N85W TO 06N105W TO 07N115W TO 07N140W. SCATTERED MODERATE CONVECTION CAN BE FOUND WITHIN 150 NM N OF THE ITCZ AXIS W OF 135W AS WELL AS WITHIN 60 NM EITHER SIDE OF THE ITCZ AXIS BETWEEN 130W AND 133W. ISOLATED MODERATE CONVECTION LIES WITHIN 90 NM S OF THE ITCZ AXIS BETWEEN 81W AND 91W. ...DISCUSSION... AN AMPLIFIED NORTHERN STREAM PATTERN IS IN PLACE OVER THE NORTHERN PORTION OF THE FORECAST AREA. A MEAN UPPER TROUGH CENTERED ALONG 105W N OF 17N...WITH ONE SPOKE FROM EASTERN TEXAS AND ALONG THE COAST OF EASTERN MEXICO AND ANOTHER FROM WEST TEXAS THROUGH BAJA CALIFORNIA TO NEAR 25N120W ASSOCIATED WITH SHORTWAVE ENERGY MOVING INTO THE BACKSIDE OF THE MEAN TROUGH. FARTHER W...THE MEAN RIDGE AXIS CAN BE FOUND FROM 30N130W TO 10N140W. THIS LONGWAVE PATTERN IS EXPECTED TO SLOWLY DRIFT E AND AMPLIFY OVER THE NEXT FEW DAYS. THE INCREASED AMPLIFICATION WILL MAKE ROOM FOR THE NEXT TROUGH AND ASSOCIATED SURFACE COLD FRONT TO MOVE INTO NW WATERS SAT BRINGING A NEW BATCH OF NW SWELL BUT LITTLE IN THE WAY OF WIND OR PRECIPITATION. THIS ADVANCING TROUGH WILL ACT TO WEAKEN THE DEEP LAYER RIDGE. AT THE SURFACE...THE HIGH PRES SYSTEM OVER THE EASTERN PACIFIC WILL WEAKEN AND DRIFT NORTHWARD A FEW DEGREES. THIS WILL CAUSE THE 20 TO 25 KT TRADE WINDS FOUND PRIMARILY BETWEEN 07N AND 18N W OF 118W...WEDGED BETWEEN THE RIDGE AXIS AND THE ITCZ AND ITS EMBEDDED SURFACE TROUGH ALONG 135W FROM 05N TO 11N...TO SLOWLY DIMINISH AND SHIFT W THROUGH SAT. ANOTHER SURFACE TROUGH EXTENDS FROM 11N115W TO 1008 MB LOW PRES 07N116W TO 03N115W. THIS SYSTEM IS STATIONARY AND EXPECTED TO MOVE LITTLE OVER THE NEXT FEW DAYS. THERE IS A DECIDED LACK OF DEEP CONVECTION NEAR THIS TROUGH AS THE SOUTHERN STREAM WESTERLY UPPER JET LIES JUST N OF THE LOW ALONG IT. CIRRUS ASSOCIATED WITH UPPER LEVEL MOISTURE TRANSPORT BY THE JET CAN BE FOUND N OF THE ITCZ W OF 100W S OF A LINE FROM 15N100W TO 07N135W. TOTAL PRECIPITABLE WATER SATELLITE IMAGERY SHOWS THAT THE LOW TO MID LEVEL MOISTURE IS POOLED SEVERAL DEGREES TO THE W OF THIS TROUGH...CLOSER TO THE WESTERN SURFACE TROUGH AND THE SCATTERED MODERATE CONVECTION W OF 130W NOTED IN THE ITCZ SECTION. AS THE MEAN TROUGH AMPLIFIES OVER MEXICO...LOOK FOR THE SOUTHERN STREAM JET TO MOVE SE AS IT STRETCHES INTO THE LEADING EDGE OF THE TROUGH. STRONG WESTERLY AND THEN NORTHWESTERLY UPPER WINDS WILL MOVE OVER THE LOW FURTHER INHIBITING DEEP CONVECTION FRI AND ESPECIALLY SAT WHEN THE SURFACE LOW IS EXPECTED TO WEAKEN. WINDS WILL ALSO DIMINISH NEAR THE LOW THROUGH THE PERIOD AS THE GRADIENT BETWEEN IT AND THE WEAKENING HIGH PRES TO THE NORTH SLACKENS. CLOSER TO LAND...THE 1708 UTC ASCAT PASS STILL SHOWS N WINDS AROUND THE 20 KT RANGE CONTINUING IN THE GULF OF CALIFORNIA. WINDS IN THIS RANGE WILL INCH NORTHWARD FRI AS THE HIGH PRES ERODES OVER EASTERN MEXICO...BUT WILL PERSIST IN THE FAR NORTHERN GULF DUE TO THE GRADIENT BETWEEN CLIMATOLOGICAL LOW PRES OVER THE EASTERN GULF OF CALIFORNIA AND PERSISTENT HIGH PRES OVER THE GREAT BASIN. GAP WINDS...GAP WINDS PERSIST THROUGH THE GULFS OF PAPAGAYO AND TEHUANTEPEC. DOWNWIND OF PAPAGAYO...SHIP ZCDG4 REPORTED NE WINDS AT 22 KT NEAR 11.5N87W AT 0000 UTC. THE COMBINATION OF STRONG TRADE WINDS IN THE CARIBBEAN AND LOCAL DRAINAGE EFFECTS WILL ALLOW THE FRESH WINDS TO PERSIST IN PAPAGAYO THROUGH TONIGHT AND THEN DIMINISH BELOW 20 KT LATE THU MORNING. WINDS AT OR ABOVE GALE FORCE CAN BE FOUND IN THE GULF OF TEHUANTEPEC BUT ARE EXPECTED TO DIMINISH BELOW GALE FORCE BY MID DAY THU. WINDS SHOULD SLOWLY DIMINISH TO 20 TO 25 KT IN TEHUANTEPEC BY SAT EVENING. FOR ADDITIONAL INFORMATION PLEASE VISIT HTTP://WWW.HURRICANES.GOV/MARINE $$ SCHAUER