000 AXPZ20 KNHC 281615 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 UTC TUE MAY 28 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 1430 UTC. ...SPECIAL FEATURE... SATELLITE IMAGERY THIS MORNING INDICATES THAT DEEP CONVECTION OCCURRING SOUTH OF THE GULF OF TEHUANTEPEC HAS INCREASED...AND APPEARS TO BE FOCUSING ABOUT A LOW PRES CENTER ALONG THE MONSOON TROUGH...NEAR 14N95.5W. SCATTERED TO NUMEROUS STRONG CONVECTION WAS OCCURRING WITHIN 120 NM NE AND 90 NM SW SEMICIRCLES...WHILE SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED FROM 09N TO 13N BETWEEN 93W AND 97.5W. SCATTERED TO NUMEROUS STRONG CONVECTION WAS ALSO NOTED FROM 12N TO 16N BETWEEN 98.5W AND 101.5W. AN OVERNIGHT ASCAT PASS SHOWED AN E-NE TO W-SW ELONGATED TROUGH ACROSS THIS AREA...WITH 20-25 KT SOUTHERLY WINDS OCCURRING WITHIN 150 NM FROM THE E END OF THIS TROUGH...AND NE TO E WINDS 20-30 KT JUST OFFSHORE OF THE COAST OF MEXICO BETWEEN 95W AND 97W. A VERY LARGE POOL OF WARN TROPICAL MOISTURE RESIDES ACROSS THIS AREA...AND CONTINUES TO PROVIDE A VERY MOIST AND UNSTABLE ENVIRONMENT. ALTHOUGH AN UPPER LEVEL TROUGH IS SWEEPING EWD ACROSS THE GULF OF MEXICO AND EXTENDS TO THE MEXICAN COAST ALONG THE BAY OF CAMPECHE...IT IS PROVIDING ANTICYCLONIC OUTFLOW ACROSS THIS AREA OF DEEP CONVECTION AND HELPING TO SUSTAIN IT. COMPUTER MODEL GUIDANCE INDICATES THAT CONDITIONS WILL REMAIN FAVORABLE FOR IMPROVED ORGANIZATION OF THIS SYSTEM...AND IT HAS A HIGH CHANCE OF BECOMING A TROPICAL CYCLONE IN THE NEXT FEW DAYS AS IT DRIFTS NORTHWARD TOWARDS THE MEXICAN COAST. VERY SHOWERS AND THUNDERSTORMS PRODUCING VERY HEAVY RAINFALL ARE EXPECTED SHIFT NORTHWARD ACROSS THE STATES OF CHIAPAS AND OAXACA DURING THE NEXT FEW DAYS AND COULD PRODUCE LIFE THREATENING FLASH FLOODING AND LANDSLIDES. SEE LATEST TROPICAL WEATHER OUTLOOK FOR MORE INFORMATION. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... MONSOON TROUGH EXTENDS FROM COLOMBIA NEAR 08.5N74W TO 09N83W TO LOW PRES NEAR 14N95.5W 1005 MB TO 12.5N99W TO 13N108W TO LOW PRES NEAR 10.5N114W 1009 MB TO 09N126W...WHERE IT TRANSITIONS TO ITCZ...CONTINUING ON TO 06N133W TO BEYOND 06N140W. SCATTERED TO NUMEROUS MODERATE TO STRONG CONVECTION FROM 03N TO 08N BETWEEN 77W AND 86W. ...DISCUSSION... ALOFT...AN UPPER TROUGH EXTENDS FROM THE NW U.S. SOUTHWARD INTO THE NW CORNER OF MEXICO NEAR 30N110W THEN TRAILS SW AS A NARROW TROUGH AXIS TO 24N120W THEN WWD TO NEAR 25N132W. AN ELONGATED W TO E RIDGE PREVAILS S OF THIS FEATURE...WITH THE W PORTION OF THE UPPER TROUGH MOVING S TO SE AND SQUASHING THE RIDGE BETWEEN 120W AND 135W. THE RIDGE CONTINUES TO THE E OF 110W...E-SE ACROSS THE EASTERN WATERS...AND INTO COLOMBIA. FARTHER WEST...A SECOND LOW IS ALSO EMBEDDED WITHIN THE MONSOON TROUGH NEAR 10.5N114W. SCATTERED MODERATE TO STRONG CONVECTION WAS NOTED WITHIN 180 NM W SEMICIRCLE OF THE LOW...WHILE SCATTERED MODERATE ISOLATED STRONG CONVECTION WAS ELSEWHERE FROM 07N TO 10N BETWEEN 117W AND 120.5W. GLOBAL MODELS SUGGEST THAT THIS LOW WILL DRIFT NORTHWARD WITHIN THE MONSOON TROUGH DURING THE NEXT FEW DAYS...WITH THE TROUGH BREAKING TO THE EAST OF 110W AS THE SOUTH OF TEHUANTEPEC BECOMES BETTER ORGANIZED. FRESH SW TO W WINDS ARE EXPECTED TO PERSIST S OF THE TROUGH IN THIS VICINITY THROUGH 48 HOURS. ELSEWHERE AT THE SURFACE...A 1028 MB HIGH WAS LOCATED JUST N OF THE AREA NEAR 31N140W AND EXTENDS A RIDGE SEWD ACROSS THE FORECAST WATERS TO NEAR 15N112W. 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 16N W OF 130W. 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 24 AND E OF 123W WITH SEAS THERE IN THE 8-11 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. WAVEWATCH GUIDANCE SUGGESTS THAT THESE SWELLS WILL SLOWLY SUBSIDE TODAY...EXCEPT FOR THE NE PORTION OF THE AREA WHERE A NEW PULSE OF NW SWELLS IS ALREADY IMPACTING THAT REGION. $$ STRIPLING