000 AXPZ20 KNHC 290936 TWDEP TROPICAL WEATHER DISCUSSION NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC FRI OCT 29 2010 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0900 UTC. ...ITCZ... THE INTERTROPICAL CONVERGENCE ZONE WAS ANALYZED FROM 08N78W TO 10N100W TO 12N120W THEN RESUMES NEAR 13N125W TO 09N140W. SCATTERED MODERATE CONVECTION WAS NOTED WITHIN 60 NM OF THE AXIS BETWEEN 125W AND 131W. ...DISCUSSION... A HIGHLY AMPLIFIED NORTHERN STREAM PATTERN HAS BROUGHT A COLD FRONT INTO THE NW WATERS FROM 32N125W TO 26N132W TO 23N140W. SATELLITE IMAGERY DEPICTS SCATTERED SHOWERS OCCURRING WITHIN 90 NM NW OF THE FRONT. A RECENT ASCAT PASS INDICATED THAT WINDS REMAIN LESS THAN 20 KT BEHIND THE FRONT ALTHOUGH IT HAS USHERED IN NW SWELL TO 15 FT. NW SWELL OF 8 FT OR GREATER WILL PROPAGATE ALL THE WAY S TO 10N BY 48 HOURS. THE FRONT WILL WEAKEN AND EVENTUALLY DISSIPATE BETWEEN 24 AND 48 HOURS AS IT CONTINUES TO MOVE E TO SE OVER THE NORTHERN PORTION OF THE AREA. A 1012 MB SURFACE LOW IS EMBEDDED IN THE ITCZ NEAR 14N122W ALONG A SURFACE TROUGH EXTENDING FROM 18N121W THROUGH THE LOW TO 12N122W. SCATTERED MODERATE CONVECTION IS OCCURRING WITHIN 120 NM OF THE LOW CENTER IN THE N QUADRANT. A RECENT ASCAT PASS MISSED THE LOW ALTHOUGH MODEL GUIDANCE AGREES ON NE WINDS TO 20 KT WITHIN 120 NM IN THE NW QUADRANT OF THE LOW. THE LOW IS EXPECTED TO DISSIPATE BETWEEN 24 AND 48 HOURS AS A RIDGE BUILDS DOWN FROM THE NW. A 1019 MB SURFACE HIGH IS POSITIONED NEAR 26N122W. THIS HIGH WILL WEAKEN AND DISSIPATE IN THE NEXT 24 HOURS AS A COLD FRONT APPROACHES FROM THE NW. A NEW AREA OF HIGH PRES WILL BUILD DOWN FROM THE NW AND N DURING THE NEXT FEW DAYS BEHIND THE AFOREMENTIONED COLD FRONT. AN ANTICYCLONE IS POSITIONED OVER NORTHERN MEXICO NEAR 29N107W WITH AN UPPER RIDGE EXTENDING SW TO NEAR 17N115W. VERY DRY AIR IS PREVALENT UNDER THIS RIDGE N OF 15N BETWEEN 100W AND 118W. A DEEP UPPER TROUGH EXTENDS FROM 32N131W TO 26N133W TO 22N140W. SW FLOW EXISTS AHEAD OF THIS TROUGH AND W OF THE UPPER RIDGE WITH MID TO UPPER LEVEL MOISTURE BEING ADVECTED FROM THE TROPICS UP INTO THE SW UNITED STATES. ANOTHER ANTICYCLONE IS CENTERED NEAR 09N139W WITH A RIDGE EXTENDING NW TO THE BIG ISLAND OF HAWAII AND E TO NEAR 10N126W. UPPER LEVEL DIFFLUENCE ON THE E TO SE SIDE OF THIS RIDGE IS AIDING IN THE DEVELOPMENT OF CONVECTION ALONG THE ITCZ. GAP WINDS... NORTHERLY WINDS ARE SURGING FROM THE SOUTHERN GULF OF MEXICO THROUGH THE CHIVELAS PASS AND INTO THE GULF OF TEHUANTEPEC. AN EARLIER 0356 UTC ASCAT PASS INDICATED 20 TO 25 KT N TO NE WINDS AND EXPECT GALE FORCE WINDS TO HAVE SINCE COMMENCED ALTHOUGH THERE HAVE BEEN NO NEW OBSERVATIONS SINCE. WINDS ARE EXPECTED TO PEAK AT AROUND 40 KT THIS EVENING THEN WILL DIMINISH TO LESS THAN GALE FORCE BY LATE SAT NIGHT. SEAS WILL BUILD TO 14 FT BY THIS EVENING THEN WILL GRADUALLY SUBSIDE ON SAT AND SAT NIGHT. $$ LEWITSKY