000 AXPZ20 KNHC 291620 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC WED MAY 29 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 ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1500 UTC. ...SPECIAL FEATURE... TROPICAL STORM BARBARA WAS CENTERED NEAR 15.7N 94.6W 995 MB AT 1500 UTC MOVING NE OR 040 DEG AT 11 KT. MAXIMUM SUSTAINED WINDS 55 KT GUSTS 65 KT. THE PUERTO ANGEL RADAR CURRENTLY SHOWS THE NORTHERN WALL OF THE INNER CORE OF BARBARA MOVING ASHORE ALONG THE COAST OF THE GULF OF TEHUANTEPEC. BARBARA WILL CONTINUE TO MOVE NE THROUGHOUT THE DAY...BRINGING BANDS OF TORRENTIAL SHOWERS AND THUNDERSTORMS ACROSS CHIAPAS...LEADING TO FLASH FLOODING AND HIGH POTENTIAL FOR MUDSLIDES. TROPICAL STORM FORCE SOUTHERLY WINDS WILL PUSH LARGE WAVES AND A MODEST STORM SURGE FROM BARBARA ASHORE ALONG THE COAST THERE. BARBARA HAS INTENSIFIED RAPIDLY OVERNIGHT...WITH DEEP CONVECTION BECOMING CONCENTRATED ABOUT THE CENTER. NUMEROUS STRONG CONVECTION WAS WITHIN 45 NM OF CENTER EXCEPT 15 NM W QUADRANT. SCATTERED TO NUMEROUS STRONG CONVECTION WAS WITHIN 90 NM SE AND 60 NM NW SEMICIRCLES. WELL SOUTH OF THE CENTER WAS NOTED SCATTERED MODERATE ISOLATED STRONG CONVECTION OCCURRING IN BANDS FROM 09N TO 14N BETWEEN 93W AND 99W. AS BARBARA MOVES FURTHER INLAND TONIGHT THROUGH THURSDAY AND GRADUALLY SPINS DOWN...STRONG MONSOONAL SW WINDS WILL TRANSPORT ABUNDANT TROPICAL MOISTURE INTO THE REGION...LEADING TO PERIODS OF SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ACROSS SOUTHEASTERN MEXICO AND GUATEMALA DURING THE NEXT 48 HOURS. HEAVY RAINFALL COULD PRODUCE ADDITIONAL FLASH FLOODING AND MUDSLIDES ACROSS THIS AREA. SEE THE LATEST NHC FORECAST/ ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC...OR THE LATEST PUBLIC ADVISORY UNDER AWIPS/WMO HEADERS MIATCPEP2/WTPZ32 KNHC...FOR MORE DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 10N74W AND MEANDERS W- NW ACROSS CENTRAL AMERICA TO NEAR 11N87W WHERE IT HAS BROKEN DUE TO T.S. BARBARA...THEN RESUMES W OF BARBARA NEAR THE COAST OF MEXICO NEAR 17N101W TO 15N105W TO LOW PRES NEAR 12N114W 1006 MB TO 08N120W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO BEYOND 05N140W. SCATTERED CLUSTERS OF MODERATE TO STRONG CONVECTION N OF 14N TO THE COAST OF MEXICO BETWEEN 97W AND 104W. ANOTHER CLUSTER OF SIMILAR CONVECTION NOTED FROM 06N TO 08N BETWEEN 80W AND 86W. ...DISCUSSION... ALOFT...AN UPPER LEVEL TROUGH ANCHORED ACROSS THE PACIFIC NW EXTENDS S-SE INTO NW MEXICO...THEN SW AS AN ELONGATING NARROW MIDDLE TO UPPER TROUGH...EXTENDING ACROSS THE S END OF BAJA CALIFORNIA TO NEAR 18N128W...WHERE IT IS DAMMING AGAINST THE TROPICAL RIDGE PREVAILING S OF 22N AND E OF 120W. TO THE W AND BROAD UPPER RIDGE DOMINATES W PORTIONS...ANCHORED ON AN UPPER ANTICYCLONE NEAR 16N137W EXTENDING A NARROW RIDGE N-NE TO NEAR 24N133W...THEN BROADENS NORTHWARD TO 40N BEHIND THE W COAST UPPER TROUGH. MONSOONAL FLOW DOMINATES THE TROPICS E OF 120W...AND IS FORECAST TO LIFT NORTHWARD DURING THE NEXT FEW DAYS...WITH BARBARA EMBEDDED WITHIN...AND ALONG W COASTAL PORTIONS OF CENTRAL AMERICA AND SOUTHERN MEXICO...AND IS EXPECTED TO PRODUCE VERY MOIST AND UNSTABLE CONDITIONS DURING THIS PERIOD. NEAR THE W END OF THE MONSOON TROUGH...A SECOND LOW PRES CENTER IS ALSO EMBEDDED WITHIN THE MONSOON TROUGH NEAR 12N114W. CONVECTION HAS BEEN FLARING ON AND OFF DURING THE PAST DAY OR SO WITH THIS FEATURE...BUT CURRENTLY SCATTERED MODERATE TO STRONG CONVECTION WITHIN WAS RESTRICTED TO WITHIN 60 NM OF CENTER EXCEPT 90 NM N QUADRANT. DRIER MIDDLE LEVEL AIR AND MODEST UPPER LEVEL CONVERGENCE PREVAILED THIS MORNING JUST TO THE N AND NE OF THIS LOW AND IS AIDING IN LIMITING CONVECTION. OVERNIGHT SCATTEROMETER PASSES SHOWED 20-30 KT WINDS WITHIN 90 NM OF CENTER EXCEPT 120 NM NW QUADRANT...WHILE STRONG MONSOONAL SW WINDS OF 20-25 KT PREVAILS TO THE S...WITHIN 210 NM ACROSS THE SE SEMICIRCLE...WHERE SEAS WERE RUNNING 8 TO 10 FT. THIS LOW IS FORECAST TO SHIFT NE OVER THE NEXT FEW DAYS AND GRADUALLY WEAKEN BY FRI. HOWEVER THERE REMAINS A MEDIUM CHANCE FOR THIS LOW TO BECOME BETTER ORGANIZED AND DEVELOP INTO A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. AT THE SURFACE...A 1026 MB HIGH LOCATED NEAR 31N144W EXTENDS A RIDGE SEWD ACROSS THE FORECAST WATERS TO NEAR 20N120W. SCATTEROMETER DATA PROVIDED OBSERVATIONS OF MODERATE TO FRESH TRADE WINDS BETWEEN THE SRN PERIPHERY OF THE RIDGE AND THE ITCZ...COVERING THE AREA FROM 10N TO 15N W OF 135W. DUE TO A TIGHT PRES GRADIENT BETWEEN THE RIDGE AND LOWER PRES OVER NW MEXICO...NW TO N WINDS HAVE INCREASED TO 20-25 KT OVER THE NE PART OF THE FORECAST REGION N OF ABOUT 27 AND E OF 122W WITH SEAS THERE IN THE 8-10 FT RANGE. EXPECT THESE MARINE CONDITIONS TO PERSIST OVER THESE WATER FOR THE NEXT 48 HOURS. LONG PERIOD CROSS EQUATORIAL SW SWELLS AT 14-16 SECONDS DOMINATE MOST OF THE FORECAST WATERS E OF 115W. THESE SWELLS ARE MERGING WITH NW TO N SWELLS THAT COVER THE REMAINDER OF THE FORECAST WATERS. SWELLS IMPACTING THE NE PORTION OF THE AREA WILL GRADUALLY SUBSIDE OVER THE NEXT COUPLE OF DAYS. $$ STRIPLING