000 AXPZ20 KNHC 260924 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC WED SEP 26 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0845 UTC. ...SPECIAL FEATURES... MIRIAM HAS WEAKENED AND NOW IS A TROPICAL STORM. IT IS CENTERED NEAR 19.5N 115.5W AT 26/0900 UTC MOVING NW OR 320 DEG AT 5 KT. A TURN TOWARD THE NORTH-NORTHWEST OR NORTH IS EXPECTED LATER TODAY. MAXIMUM SUSTAINED WIND SPEED IS 60 KT WITH GUSTS TO 75 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 990 MB. MOST OF THE SIGNIFICANT THUNDERSTORM ACTIVITY ASSOCIATED WITH MIRIAM IS NORTH OF THE CENTER. NUMEROUS MODERATE TO STRONG CONVECTION IS NOTED FROM 19N TO 22N BETWEEN 114W AND 117W. SCATTERED MODERATE CONVECTION IS ELSEWHERE FROM 18N TO 20N BETWEEN 111W AND 115W AND FROM 20N TO 23N BETWEEN 114W AND 117W. SWELLS GENERATED BY MIRIAM WILL AFFECT THE SOUTH AND WEST COASTS OF THE SOUTHERN AND CENTRAL BAJA PENINSULA DURING THE NEXT COUPLE OF DAYS. THESE SWELLS ARE LIKELY TO CAUSE LIFE-THREATENING SURF AND RIP CURRENT CONDITIONS. SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP3/WTPZ23 KNHC FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM 09N84W TO 1008 MB LOW PRES NEAR 12N104W TO O9N110W...WHERE IT FRACTURES...THEN RESUMES FROM S OF MIRIAM NEAR 14N116W TO 12N130W TO BEYOND 11N140W. SCATTERED MODERATE ISOLATED STRONG FROM 06N TO 10N BETWEEN 87W AND 96W...AND BETWEEN 101W AND 110W. SIMILAR CONVECTION IS FROM 10N TO 16N BETWEEN 101W AND 106W. ...DISCUSSION... UPPER LEVEL RIDGING EXTENDS NEARLY E TO W ALONG 16-18N AND FROM 07N TO 26N...BETWEEN SE MEXICO AND 144W...WITH TWO DISTINCT ANTICYCLONIC CIRCULATIONS ON EACH END OF RIDGE. ONE IS NEAR 17N105W AND THE OTHER IS NEAR 17N135W. SW TO W FLOW GENERALLY PREVAILS N OF THE RIDGE...WITH A MIDDLE TO UPPER LEVEL TROUGH EXTENDING IN BETWEEN THE TWO ANTICYCLONES ALONG 119W/120W. THIS TROUGH IS PRODUCING SOME SWLY WIND SHEAR OVER MIRIAM THAT IS LOSING STRENGTH QUICKLY. ABUNDANT MID TO UPPER LEVEL MOISTURE IS NOTED OVER THE NW CORNER OF THE AREA. A 1026 HIGH CENTERED NEAR 35N140W EXTENDS A RIDGE ACROSS NW PORTIONS TO NEAR 24N124W. AN AREA OF FRESH TRADE WINDS ON THE SOUTHERN PERIPHERY OF THE RIDGE IS IDENTIFIED BY THE MOST RECENT SCATTEROMETER PASSES FROM 13N TO 17N W OF 132W...WHERE SEAS ARE RUNNING 8-10 FT IN MIXED NW SWELL AND BUILDING WIND WAVES. THE AERIAL EXTENT OF THE FRESH TRADES WILL DECREASE DURING THE NEXT 24 HOURS AS HIGH PRES WEAKENS. A WEAK LOW PRES HAS DEVELOPED ALONG THE MONSOON TROUGH NEAR 12N104W. CLUSTERS OF MODERATE TO ISOLATED STRONG CONVECTION ARE NOTED AROUND THE LOW LEVEL CYCLONIC CIRCULATION THERE MAINLY FROM 08N TO 13N BETWEEN 102W AND 106W. ANY DEVELOPMENT OF THIS DISTURBANCE SHOULD BE SLOW TO OCCUR DUE TO STRONG UPPER-LEVEL WINDS. COMPUTER MODELS SUGGEST THAT THIS LOW PRES WILL DISSIPATE IN ABOUT 36-48 HOURS WITH A TROUGH REMAINING IN THAT AREA. TWO SWELL EVENTS PLUS SEAS GENERATED BY HURRICANE MIRIAM ARE IMPACTING THE REGIONAL WATERS. MODERATE TO LARGE LONG PERIOD SWELLS FROM THE NW ARE SPREADING ACROSS THE NW WATERS...RAISING SEAS TO 7-9 FT TO THE W AND NW OF MIRIAM. MEANWHILE...A NEW PULSE OF CROSS EQUATORIAL SW SWELLS HAS MOVED THROUGH SE PORTIONS AND REACHED THE COAST OF MEXICO AND CENTRAL AMERICA WITH ANOTHER STRONG PULSE TO FOLLOW TODAY AND TONIGHT. THESE SWELLS ARE ALREADY MERGING WITH SEAS OF 8 TO 11 FT AFFECTING MOST OF THE FORECAST WATERS W OF 105W. SWELLS GENERATED BY HURRICANE MIRIAM WILL CONTINUE TO REACH THE COASTS OF MEXICO TO PRODUCE STRONG AND LARGE SURF AND DANGEROUS RIP CURRENTS WITHIN THE SURF ZONE FROM THE SOUTH HALF OF BAJA CALIFORNIA TO NEAR ACAPULCO. SOUTHERLY SWELL FROM MIRIAM HAS MOVED THROUGH THE ENTRANCE INTO THE GULF OF CALIFORNIA AND WILL CREATE SIMILAR CONDITIONS ALONG EXPOSED COASTLINES S OF 26N TODAY. $$ GR