000 AXPZ20 KNHC 122238 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI 2205 UTC THU SEP 12 2013 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2115 UTC. ...TROPICAL LOWS... SATELLITE IMAGERY THIS AFTERNOON SUGGESTS THAT LOW PRES HAS BEGUN TO DEVELOP NEAR 14.5N100W...ESTIMATED AT 1004 MB...AND IS EMBEDDED ALONG THE MONSOON TROUGH THERE THAT CONTINUES ON NE INTO THE GULF OF TEHUANTEPEC. A BROAD ZONE OF FRESH SW WINDS 20 TO 25 KT EXTENDS WELL TO THE S AND SE OF THIS LOW TO 08.5N AND 97W....WHERE A MID DAY ALTIMETER PASS CONFIRMED SEAS 8 TO 12 FT. THIS BROAD AREA OF FRESH TO STRONG SW MONSOONAL FLOW IS EXPECTED TO CONTINUE FOR THE NEXT FEW DAYS AND WILL MAINTAIN AN ENVIRONMENT FAVORABLE FOR SMALL LOW CENTERS TO FORM IN THIS GENERAL AREA. ABUNDANT TROPICAL MOISTURE PERSISTS ACROSS THE REGION...AND SURFACE PRESSURE AREA BELOW NORMAL IN THE REGION...AND IMPROVED ORGANIZATION OF THIS LOW CENTER COULD OCCUR DURING THE NEXT FEW DAYS AS THE LOW DRIFTS OFF TOWARDS THE NW. THIS SYSTEM HAS A MEDIUM CHANCE OF BECOMING A TROPICAL CYCLONE IN THE NEXT 48 HOURS. REGARDLESS OF TROPICAL CYCLONE DEVELOPMENT...CLUSTERS OF MODERATE TO STRONG CONVECTION WILL CONTINUE INTERMITTENTLY ACROSS THE PACIFIC COASTAL ZONES OF SOUTHERN MEXICO DURING THE NEXT 48 HOURS...AND WILL LEAD TO PERIODS OF HEAVY RAIN...WHICH COULD CAUSE LIFE-THREATENING FLASH FLOODING AND MUDSLIDES. STRONG ONSHORE SW WINDS WILL ALSO PRODUCE VERY ROUGH SEAS AND STRONG CONFUSED SURF...LEADING TO DANGEROUS SURF CONDITIONS AND WIDESPREAD RIP CURRENTS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS RATHER ILL DEFINED ACROSS E PORTIONS OF THE AREA...AND MEANDERS FROM THE EXTREME SW CARIB NEAR 11N80W AND MEANDERS NW ACROSS CENTRAL AMERICA TO LOW PRES ACROSS THE BAY OF CAMPECHE...THEN EXTENDS S-SW ACROSS MEXICO AND THROUGH THE GULF OF TEHUANTEPEC TO NEAR 15N97W TO DEVELOPING LOW PRES NEAR 14.5N100W TO 12.5N108W TO 15N117W TO LOW PRES 11.5N122.5W TO 08N128W TO 08.5N136W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO BEYOND 09N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION WITHIN 210 NM SW OF CENTRAL AMERICAN COAST BETWEEN 78W AND 92W. SCATTERED STRONG CONVECTION NOTED WITHIN 60 NM OF LOW PRES NEAR 14.5N100W. SCATTERED STRONG CONVECTION NOTED ELSEWHERE FROM 13N TO 16N BETWEEN 92W TO 108W. SCATTERED MODERATE ISOLATED STRONG CONVECTION NOTED ELSEWHERE FROM 08N TO 17.5N BETWEEN 101W AND 112W. ISOLATED MODERATE CONVECTION WITHIN 180 NM W QUADRANT OF LOW PRES 11.5N122.5W. ...DISCUSSION... AN UPPER LEVEL BLOCKING PATTERN PERSISTS ACROSS THE NE PACIFIC THIS AFTERNOON...WITH LITTLE OVERALL MOVEMENT OF THE MAIN SYNOPTIC FEATURES. A DEEP LAYERED UPPER CYCLONE REMAINS TO THE NW OF THE AREA WITH TROUGH EXTENDING S TO NEAR 30N142W THEN SW...WHICH HAS PUSHED A WEAK FRONTAL TROUGH EXTENDING NE TO SW ACROSS THE EXTREME NW CORNER OF THE AREA NEAR 30N140W. THE FRONT IS EXPECTED TO STALL DURING THE NEXT FEW DAYS AND GRADUALLY DISSIPATE FROM 32N133W TO 26140W ON SAT. EXPECTING ONLY A 10-15 KT N TO NE WIND SHIFT ALONG THE FRONTAL BOUNDARY WITH SEAS 6-7 FT IN NW SWELL. AN UPPER RIDGE REMAINS TO THE E OF THIS ALONG 125W AND N OF 28N...WHILE A DEEP LAYERED UPPER CYCLONE REMAINS ACROSS THE SW U.S. BUT HAS SHIFTED N DURING THE PAST 24 HOURS N NEVADA. UPPER RIDGING ALSO PREVAILS S OF THESE FEATURES...EXTENDING FROM AN UPPER ANTICYCLONE OVER N MEXICO NEAR 29N105W...EXTENDING SW TO THE S TIP OF BAJA CALIFORNIA THEN WWD ALONG 22N TO 133W THEN SW INTO THE DEEP TROPICS. THIS UPPER RIDGE CONTINUES TO PRODUCE MODEST NE TO E WINDS AT UPPER LEVELS ACROSS THE AREA S OF 20N AND E OF 110W...WHICH IS A FAVORABLE FOR SUSTAINED CONVECTION ACROSS THE AREA. THESE FAVORABLE CONDITIONS ARE EXPECTED TO PERSIST THROUGH FRIDAY. AT LOWER LEVELS...THE MONSOON CIRCULATION ACROSS THE REGION E OF 120W REMAINS WELL ESTABLISHED...WITH STRONG W TO SW FLOW DRAWING ABUNDANT MOISTURE INTO E PORTIONS AND ACROSS CENTRAL AMERICA...THE SOUTH HALF OF MEXICO...AND THE BAY OF CAMPECHE. A ZONE OF STRONG S TO SW WINDS OF 20 TO 25 KT WITH ISOLATED AREAS TO 30 KT IS EXPECTED TO PREVAIL THROUGH SATURDAY...GENERALLY FROM 08N TO 15N BETWEEN 96W AND 104W THEN CONTINUING BETWEEN 08N AND 12N TO 110W. SEAS ACROSS THE REGION ARE EXPECTED TO REMAIN 8- 10 FT WITH AREAS TO 11 AND 12 FT. THIS LOW LEVEL WIND AND WAVE PATTERN WILL SHIFT SLIGHTLY WWD ON SUN AND CONTINUE TO GENERATE HIGH SEAS OFFSHORE OF SOUTHERN MEXICO. $$ STRIPLING