000 AXPZ20 KNHC 261603 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1445 UTC. ...SPECIAL FEATURES... TROPICAL STORM MIRIAM. IT IS CENTERED NEAR 20.0N 115.7W AT 26/1500 UTC MOVING NNW OR 330 DEG AT 5 KT. MAXIMUM SUSTAINED WIND SPEED IS 55 KT WITH GUSTS TO 65 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 992 MB. MOST OF THE SIGNIFICANT THUNDERSTORM ACTIVITY ASSOCIATED WITH MIRIAM IS NORTH OF THE CENTER. NUMEROUS MODERATE TO STRONG FROM 19N TO 24N BETWEEN 114W AND 118W. 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 09N90W TO 13N100W TO 1007 MB LOW PRES NEAR 12N104W TO 13N108W WHERE IT FRACTURES...THEN RESUMES FROM S OF MIRIAM NEAR 14N117W TO 12N120W TO BEYOND 10N140W. SCATTERED MODERATE CONVECTION IS FROM 05N TO 11N BETWEEN 85W AND 98W. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS FROM 07N TO 17N BETWEEN 100W AND 110W. SCATTERED MODERATE CONVECTION IS ALSO FROM 11N TO 14N BETWEEN 113W AND 117W. ...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 1025 HIGH CENTERED NEAR 35N142W EXTENDS A RIDGE ACROSS NW PORTIONS TO NEAR 25N124W. 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 SCATTERED MODERATE TO ISOLATED STRONG CONVECTION ARE NOTED AROUND THE LOW LEVEL CYCLONIC CIRCULATION THERE MAINLY FROM 07N TO 17N BETWEEN 100W AND 110W. 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 T.S 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. $$ FORMOSA