000 AXPZ20 KNHC 151601 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC SUN MAY 15 2011 TROPICAL WEATHER DISCUSSION FOR THE EASTERN PACIFIC OCEAN FROM THE EQUATOR TO 32N...EAST OF 140W. BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1515 UTC. ...ITCZ AND TROPICAL CONVECTION... AXIS FROM 08N103W TO 05N112W TO 03N140W. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED WITHIN 120 NM OF AXIS BETWEEN 103W AND 126W. A MONSOON TROUGH IS ANALYZED ACROSS CENTRAL AMERICA FROM 08.5N80W AND 14N92W. SCATTERED TO LOCALLY NUMEROUS MODERATE TO STRONG CONVECTION WAS NOTED FROM 02N TO 07N E OF 97W AND FROM 03N TO 12N BETWEEN 97W AND 103W. SCATTERED MODERATE TO STRONG CONVECTION WAS ALSO NOTED WITHIN 180 NM OF COAST OF CENTRAL AMERICA FROM 85W TO 98W. DEEP CONVECTION THAT DEVELOPED OVERNIGHT ACROSS S PORTIONS OF MEXICO MOVED S TO SW EARLY THIS MORNING...AND OFFSHORE ACROSS THE GULF OF TEHUANTEPEC REGION...AND HAS SINCE DIMINISHED CONSIDERABLY. ...DISCUSSION... AN UPPER LEVEL TROUGH DOMINATES THE WESTERN SEABOARD OF N AMERICA WITH A DEEP LAYERED CYCLONE NEAR 40N127W WITH A MID TO UPPER TROUGH EXTENDING S OVER THE DISCUSSION AREA ALONG 30N130W TO A BASE OVER THE TROPICS AT 17N140W. THE DEEP LAYERED LOW IS REFLECTED AT THE SURFACE BY A 1005 MB LOW NEAR 39N125W WITH AN ATTENDANT WEAK COLD FRONT EXTENDING FROM SRN CALIFORNIA SW ACROSS 30N122W TO 27N130W TO 26N138W. A SMALL AREA OF 20 KT WINDS WERE NOTED BEHIND THIS FRONT...WITH SEAS OF 8 TO 10 FT IN NW SWELL MOVING INTO THE AREA. ACTIVE CONVECTION ACROSS THE TROPICS E OF 135W...AND NEAR THE ITCZ AND MONSOONAL TROUGH ARE ACTING TO HELP MAINTAIN UPPER LEVEL RIDGING ACROSS AND SEVERAL DEGREES N OF THE CONVECTION. AN EQUATORIAL MID TO UPPER CYCLONE WAS NOTED IN WATER VAPOR IMAGERY NEAR 01N127W WITH A WEAKNESS EXTENDING N TO NEAR 14N118W. AN UPPER RIDGE TO THE E OF THIS TROUGHING WAS AIDING IN AMPLIFYING THE TROUGH THIS MORNING...AND SEPARATED TWO ZONES OF ANTICYCLONIC FLOW ALOFT ON EITHER SIDE. A BROAD UPPER RIDGE CONTINUES ACROSS E PORTIONS OF THE AREA E OF 112W EXTENDING N AND NW ACROSS MUCH OF MEXICO...BUT WITH NO CLEAR ANTICYCLONIC CENTER EVIDENT IN SATELLITE IMAGERY. DEEP TROPICAL CONVECTION FUELED BY THE MODEST MONSOONAL FLOW ACROSS THIS AREA CONTINUES TO MAINTAIN DIVERGENT FLOW ALOFT S OF 09N BETWEEN 80W AND 100W. AT THE LOW LEVELS...A BROAD SURFACE RIDGE EXTENDS FROM A 1029 MB HIGH NEAR 33N149W...BRIDGING ACROSS THE WEAKENING COLD FRONT TO 19N112W. A TIGHT PRESSURE GRADIENT NE OF THE RIDGE IS MAINTAINING NW WINDS NEAR 20 KT...WITH SEAS 7 TO 9 FT....WITHIN ABOUT 150 NM W AND SW OF THE BAJA CALIFORNIA PENINSULA. THE COLD FRONT WILL MOVE E AND ACROSS THE REMAINDER OF SRN CALIFORNIA AND NRN BAJA CALIFORNIA THIS AFTERNOON AND EARLY EVENING...AND FRESHEN THE NW FLOW OFF THE BAJA COAST TONIGHT THROUGH TUE NIGHT...AS THE HIGH PRES RIDGE BUILDS BEHIND THE FRONT. TO THE E AND SE OF THE RIDGE...BROAD AND WEAK MONSOONAL FLOW PREVAILS IN THE LOW LEVELS. A WEAK LATE SEASON FRONTAL BOUNDARY SWEEPING ACROSS THE GULF OF MEXICO IS REINFORCING NLY LOW LEVEL FLOW ACROSS CENTRAL AMERICA AND PRODUCING MODEST LLVL FORCING ACROSS THE TROPICAL EPAC E OF 100W...WHICH HELPS TO EXPLAIN THE RECENT VERY ACTIVE CONVECTION. THIS NORTHERLY LOW LEVEL FLOW IS EXPECTED TO BEGIN TO DIMINISH LATER THIS AFTERNOON AND TONIGHT WHICH WILL RESULT IN THE DEEP CONVECTION ACROSS THIS AREA BEGINNING TO SHIFT E OF 95W. S TO SW WINDS NEAR 20 KT WERE OCCURRING S OF THIS ZONE OF ACTIVE CONVECTION BETWEEN 83W AND 104W THIS MORNING AND ARE EXPECTED TO DIMINISH SLIGHTLY AND BECOME MORE SW TO W THROUGH MON. A VERY STRONG PULSE OF LARGE LONG PERIOD SRN HEMI SWELL WAS APPROACHING THE EQUATOR THIS MORNING AND IS EXPECTED TO INVADE THE AREA WATERS TONIGHT THROUGHOUT THE NEXT SEVERAL DAYS. THESE SOUTHERLY SWELLS ARE FORECAST TO ARRIVE ALONG THE COAST OF CENTRAL AMERICA AND THE SOUTHERN BAJA CALIFORNIA PENINSULA AT NEAR 21 SECONDS MON NIGHT...AND BUILD ACROSS THE AREA WATERS TUE AND WED. VERY LARGE SURF WILL BE SEEN ALONG THE COASTS AND SHOALS OF THE REGION DURING THIS TIME...WITH OFFSHORE WAVE HEIGHTS FORECAST TO BUILD TO 9 TO 10 FT BY WED AFTERNOON. $$ STRIPLING