000 AXPZ20 KNHC 290914 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0845 UTC. ...SPECIAL FEATURE... TROPICAL STORM BARBARA CENTERED NEAR 14.8N 95.6W AT 29/0900Z MOVING NE OR 35 DEGREES AT 4 KT. ON THE FORECAST TRACK...THE CENTER OF BARBARA SHOULD REACH THE COAST IN THE GULF OF TEHUANTEPEC LATER TODAY. ESTIMATED MINIMUM CENTRAL PRESSURE IS 997 MB. MAXIMUM SUSTAINED WIND SPEED IS 50 KT GUSTS TO 60 KT. THE SATELLITE PRESENTATION OF BARBARA HAS IMPROVED DRAMATICALLY OVERNIGHT AND THE RADAR FROM PUERTO ANGEL SHOWS A PARTIAL EYEWALL. NUMEROUS MODERATE TO STRONG CONVECTION IS WITHIN 90 NM OF CENTER. SCATTERED MODERATE TO ISOLATED STRONG CONVECTION IS IN A 90 NM WIDE BAND ALONG 15N93W 11N94W. SIMILAR CONVECTION IS ALSO SEEN FARTHER SOUTH FROM 09N TO 11N BETWEEN 93W AND 97W UNDER A SOUTHWESTERLY FLOW FEEDING INTO THE STORM. BARBARA IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF 4 TO 8 INCHES OVER EASTERN OAXACA AND WESTERN CHIAPAS MEXICO...WITH ISOLATED MAXIMUM AMOUNTS OF 12 INCHES POSSIBLE IN SOUTHEASTERN OAXACA. DUE TO THE EXPECTED SLOW MOTION OF BARBARA AND ITS REMNANTS...AS WELL AS THE MOUNTAINOUS TERRAIN IN AND NEAR THE LANDFALL AREA... THE BIGGEST HAZARD WILL LIKELY BE HEAVY RAINFALL AND THE POTENTIAL FOR FLASH FLOODING AND MUD SLIDES. TROPICAL STORM CONDITIONS ARE EXPECTED TO REACH THE COAST THIS MORNING. 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 10N86W TO 14N90W THEN RESUMES W OF TROPICAL STORM BARBARA AND LOW PRES LOCATED NEAR 12N114W TO 09N121W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 07N140W. CLUSTER OF MODERATE TO STRONG CONVECTION IS N OF 10N TO THE COAST OF NICARAGUA BETWEEN 86W AND 88W. THE REMAINDER OF THE SIGNIFICANT CONVECTION IS MAINLY ASSOCIATED WITH BARBARA AND THE SURROUNDING AREA. ...DISCUSSION... ALOFT...AN UPPER TROUGH EXTENDS FROM NW MEXICO TO 24N120W THEN NW TO NEAR 27N132W. AN ELONGATED W TO E RIDGE PREVAILS S OF THIS FEATURE...WITH A COUPLE OF ANTICYCLONES...ONE NEAR 16N115W AND THE OTHER NEAR 20N135W. AN UPPER LEVEL TROUGH OVER THE GULF OF MEXICO HAS ITS BASE OVER SE MEXICO. ANTICYCLONIC FLOW DOMINATES CENTRAL AMERICA AND THE REMAINDER OF THE FORECAST AREA. FARTHER WEST...A SECOND LOW IS ALSO EMBEDDED WITHIN THE MONSOON TROUGH NEAR 12N114W. CONVECTION IS LIMITED IN ASSOCIATION WITH THIS SYSTEM. ONLY SCATTERED MODERATE CONVECTION IS WITHIN 30 NM AND 90NM W QUADRANT. GLOBAL MODELS SUGGEST THAT THIS LOW WILL DRIFT NORTHWARD WITHIN THE MONSOON TROUGH DURING THE NEXT FEW DAYS REACHING MAXIMUM WINDS OF 30 KT IN 24 HOURS THEN WILL GRADUALLY WEAKEN DURING THE NEXT 48-72 HOUR. THE EDGE OF AN 0526 UTC ASCAT PASS CAPTURED THE WESTERN CIRCULATION OF THE LOW WITH WINDS OF 20-25 KT. ELSEWHERE 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. $$ GR