000 AXPZ20 KNHC 290238 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC TUE SEP 29 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 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0230 UTC. ...SPECIAL FEATURE... HURRICANE MARTY IS CENTERED AT 16.7N 102.0W...OR ABOUT 75 MILES SSW OF ZIHUATANEJO MEXICO AND 140 MILES W OF ACAPULCO MEXICO AT 0300 UTC WITH AN ESTIMATED PRESSURE OF 989 MB. MAXIMUM SUSTAINED WINDS ARE 65 KT KT WITH GUSTS TO 80 KT. SCATTERED MODERATE TO STRONG CONVECTION IS OBSERVED WITHIN 45 NM OF CENTER. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED ELSEWHERE WITHIN 150 NM OF LINE FROM 17N100W TO 14N104W. MARTY IS MOVING E- NE...OR 070 DEG AT 03 KT AND LITTLE CHANGE IS EXPECTED TONIGHT AND TUE...THEN A TURN TO THE N IS EXPECTED ON WED. ALTHOUGH THE CENTER OF MARTY IS FORECAST TO REMAIN JUST OFFSHORE THE MEXICAN COAST...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 10N76W TO THE PACIFIC COAST OF COSTA RICA AT 10N85W...THEN CONTINUES WSW THROUGH A NEWLY FORMED 1008 MB LOW PRESSURE CENTER EMBEDDED IN THE MONSOON TROUGH AT 09N91W TO 09N97W 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 15N105W AND WIGGLES W TO 14N117W...THEN TURNS SW THROUGH AN EMBEDDED 1008 MB LOW PRESSURE AT 12N121W TO 08N128W...THEN TURNS NW TO BEYOND 13N140W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 90 NM EITHER SIDE OF A LINE FROM 06N84W TO 08N98W...AND WITHIN 150 NM EITHER SIDE OF A LINE FROM 13N107W TO 11N120W TO 06N133W TO 13N140W. THE SURFACE LOW ANALYZED AT 12N121W WILL MOVE NE TO A POSITION NEAR 12N117W LATE TUE AND NEAR 13N117W LATE WED. THE GRADIENT HAS RELAXED SE OF THE LOW SUPPORTING SOUTHERLY 15-20 KT FLOW ACROSS THE WATERS FROM 05-12N BETWEEN 105-102W. CROSS EQUATORIAL SOUTHERLY SWELL IS MIXING WITH LONG PERIOD NW SWELL...RESULTING IN COMBINED SEAS OF 7-10 FT ROUGHLY TO THE S OF 11N BETWEEN 95- 125W. MEDIUM RANGE GUIDANCE HANGS ON TO THIS LOW AND GRADUALLY MOVES IT NE DURING THE LATER PART OF THE WEEK WHEN IT WILL HAVE THE POTENTIAL FOR TROPICAL CYCLONE FORMATION. A 104 MB SURFACE HIGH IS CENTERED AT 29N127W WITH A RIDGE EXTENDING SE TO 19N110W. A 1009 MB OCCLUDED LOW IS CENTERED N OF THE AREA NEAR 34N135W TRAILING A WEAK COLD FRONT S ACROSS THE DISCUSSION AREA FROM 32N129W TO 27N134W WHERE IT BECOMES STATIONARY TO BEYOND 21N140W. ALTHOUGH NORTHERLY WINDS W OF THE FRONT ARE IN THE 15-20 KT RANGE...COMBINED SEAS 0F 7-11 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