000 AXPZ20 KNHC 282147 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 2205 UTC MON SEP 28 2015 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 1800 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 2145 UTC. ...SPECIAL FEATURE... HURRICANE MARTY IS CENTERED AT 16.7N 102.1W...OR ABOUT 75 MILES SSW OF ZIHUATANEJO MEXICO AND 145 MILES W OF ACAPULCO MEXICO AT 2100 UTC WITH AN ESTIMATED PRESSURE OF 986 MB. MAXIMUM SUSTAINED WINDS HAVE INCREASED TO 70 KT WITH GUSTS TO 85 KT. A BURST OF STRONG CONVECTION THAT OCCURRED EARLIER HAS REACHED MATURITY... AND NOW ONLY SCATTERED STRONG CONVECTION IS OBSERVED WITHIN 150 NM OVER THE N QUADRANT OF CENTER. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED ELSEWHERE WITHIN 90 NM EITHER SIDE OF A LINE FROM 18N104W TO 14N98W. MARTY IS MOVING NE...OR 045 DEG AT 05 KT AND IS EXPECTED TO SLOW TONIGHT AND TUE...THEN TURN TO THE N ON WED. ALTHOUGH THE CENTER OF MARTY IS FORECAST TO REMAIN OFFSHORE...HEAVY RAINFALL IS EXPECTED TO PRODUCE LIFE- THREATENING FLASH FLOODS AND MUDSLIDES...ESPECIALLY IN AREAS OF ELEVATED TERRAIN...ACROSS THE MEXICAN STATES OF GUERRERO AND MICHOACAN THROUGH THU. DANGEROUS STORM SURGE CONDITIONS WILL PRODUCE SIGNIFICANT COASTAL FLOODING IN AREAS OF ONSHORE FLOW AND ALSO BE ACCOMPANIED BY LARGE AND DESTRUCTIVE WAVES AND SWELLS RESULTING IN DANGEROUS SURF AND RIP CURRENTS. INTERESTS ARE ENCOURAGED TO REFER TO THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR UPDATED DETAILS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS ANALYZED BETWEEN 09-10N FROM THE CARIBBEAN COAST OF COLOMBIA AT 11N74W TO THE PACIFIC COAST OF COSTA RICA AT 09N84W...THEN CONTINUES WSW TO 08N95W WHERE IT LOSES IDENTITY IN THE BROAD CYCLONIC CIRCULATION ASSOCIATED WITH TROPICAL CYCLONE MARTY. SCATTEROMETER WINDS SUGGEST THAT THE MONSOON TROUGH RESUMES SW OF MARTY NEAR 15N110W...AND CONTINUES SW THROUGH AN EMBEDDED 1009 MB LOW PRESSURE AT 12N118W TO 08N128W...THEN TURNS NW TO A 1010 MB EMBEDDED LOW PRESSURE AT 13.5N137W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 180 NM OF 09N94.5WRKW...AND ALSO WITHIN 120 NM EITHER SIDE OF A LINE FROM 13.5N105W TO 12N118W TO 04N129W TO 13N137W. THE SURFACE LOW AT 12N118W WILL MOVE NE TO A POSITION NEAR 12N116W TUE AND NEAR 12.5N117W ON WED. SOUTHERLY FLOW OF 20-25 KT IS OBSERVED WITHIN 270 NM SE OF THE LOW WITH 7-10 FT SEAS. CROSS EQUATORIAL SOUTHERLY SWELL IS MIXING WITH LONG PERIOD NW SWELL...RESULTING IN COMBINED SEAS OF 7-9 FT...SURROUNDING THIS AREA OF STRONGER SOUTHERLY WINDS ROUGHLY TO THE S OF 11N BETWEEN 92-126W. MEDIUM RANGE GUIDANCE HANGS ON TO THIS LOW AND GRADUALLY MOVES IT NE DURING THE LATER PART OF THE WEEK WHEN IT HAS THE POTENTIAL FOR TROPICAL CYCLONE FORMATION. A SURFACE HIGH IS CENTERED AT 29N126W WITH A RIDGE EXTENDING SE TO 15N115W. A 1009 MB OCCLUDED LOW IS CENTERED AT 33N135W TRAILING A WEAK COLD FRONT SW ACROSS THE DISCUSSION AREA FROM 30N130W TO 25N134W WHERE IT BECOMES STATIONARY TO BEYOND 20N140W. ALTHOUGH NORTHERLY WINDS W OF THE FRONT ARE IN THE 15- 20 KT RANGE...COMBINED SEAS 0F 7-10 FT ARE OBSERVED. THE FRONT WILL FURTHER WEAKEN ALONG POSITION FROM 32N133W TO 25N135W TO 20N140W ON TUE. BY THEN WINDS W OF THE FRONT WILL HAVE DIMINISHED TO 10-15 KT AND SEAS SUBSIDED TO 4-7 FT. $$ NELSON