000 AXPZ20 KNHC 270249 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC SUN SEP 27 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... TROPICAL STORM MARTY IS CENTERED AT 13.6N 103.0W...OR ABOUT 305 MILES SW OF ACAPULCO MEXICO...AT 0300 UTC WITH AN ESTIMATED PRESSURE OF 1003 MB. MARTY IS MOVING N...OR 360 DEG AT 04 KT. MAXIMUM SUSTAINED WINDS ARE 35 KT WITH GUSTS 45 KT WITHIN 40 NM E OF THE CENTER WITH 20 TO 33 KT WINDS OBSERVED ELSEWHERE WITHIN 270 NM SE SEMICIRCLE...AND WITHIN 120 NM OVER THE NW SEMICIRCLE. CURRENTLY NUMEROUS STRONG CONVECTION IS FLARING WITHIN 75 NM OVER THE NE AND WITHIN 45 NM OVER SW SEMICIRCLES OF CENTER. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS NOTED WITHIN 150 NM EITHER SIDE OF A LINE FROM 16N98W TO 09N109W. A TURN TOWARDS THE NE IS EXPECTED ON SUN. THE STORM IS FORECAST TO GRADUALLY STRENGTHEN FOR A COUPLE OF DAYS TO A STRONG TROPICAL STORM...THEN INCREASING WIND SHEAR WILL RESULT IN A WEAKENING TREND. ASSOCIATED SQUALLS AND BUILDING SEAS WILL REACH THE PACIFIC COAST OF MEXICO BETWEEN 98-105W THROUGH THE MIDDLE OF NEXT WEEK. INTERESTS ARE ENCOURAGED TO REFER TO THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP2/WTPZ22 KNHC FOR UPDATED DETAILS. ...TROPICAL LOW AND TROPICAL WAVES... A 1006 MB LOW PRESSURE IS EMBEDDED WITHIN THE MONSOON TROUGH AT 10.5N119W...BUT IS ONLY CURRENTLY ACCOMPANIED BY ISOLATED MODERATE TO STRONG CONVECTION WITHIN 210 NM OVER THE NW SEMICIRCLE OF THE CENTER. CYCLONIC SURFACE WINDS OF ONLY 5-10 KT ARE FORECAST WITHIN 150 NM OF THE CENTER THROUGH THE WEEKEND...THEN THE GRADIENT WILL TIGHTEN SUPPORTING SW 15-25 KT WINDS WITHIN ABOUT 480 NM OVER THE SE SEMICIRCLE BEGINNING ON MON NIGHT WITH SEAS BUILDING TO 10 FT IN MIXED WIND WAVE AND CROSS EQUATORIAL SOUTHERLY SWELL. A TROPICAL WAVE TROUGH IS ANALYZED FROM 11N140W TO 17N138W AND APPEARS STATIONARY. CURRENTLY ISOLATED MODERATE TO STRONG CONVECTION IS NOTED WITHIN 90 NM OF THE TROUGH AXIS. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH IS ANALYZED ALONG 10N FROM THE CARIBBEAN COAST OF COLOMBIA AT 10N76W TO THE PACIFIC COAST OF COSTA RICA AT 10N85W...THEN TURNS NW TO NEAR 14N99W WHERE IT LOSES IDENTITY IN THE INCREASING BROAD CYCLONIC CIRCULATION ASSOCIATED WITH TROPICAL STORM MARTY. SCATTEROMETER WINDS SUGGEST THAT THE MONSOON TROUGH RESUMES SW OF MARTY NEAR 12N110W AND CONTINUES SW TO 09N125W...THEN TURNS NW TO 10N130W WHERE SCATTEROMETER WINDS INDICATE A TRANSITION TO AN ITCZ AXIS...WHICH CONTINUES W TO 10N140W. EXCEPT AS PREVIOUSLY DESCRIBED IN ASSOCIATION WITH MARTY AND THE TROPICAL LOW AND TROPICAL WAVE NEAR 140W... ISOLATED MODERATE AND STRONG CONVECTION IS NOTED N OF 10N BETWEEN 86W AN 97W. SCATTERED MODERATE ISOLATED STRONG CONVECTION IS OBSERVED WITHIN 120 NM EITHER SIDE OF A LINE FROM 10N108W TO 05N124W AND WITHIN THE AREA FROM 04-09N BETWEEN 133- 140W. ...DISCUSSION... A SURFACE RIDGE EXTENDS SE FROM 32N130W TO 17N110W. A 1016 MB SURFACE LOW IS ANALYZED NEAR 33N136W AND IS TRAILING A NEAR STATIONARY AND WEAK COLD FRONT SW ACROSS THE DISCUSSION AREA FROM 30N136W TO BEYOND 27N140W. A SECONDARY...STRONGER COLD FRONT WILL PUSH SE INTO THE FAR NW WATERS ON SUN AS THE LOW CENTER OCCLUDES. STRENGTHENING HIGH PRESSURE NW OF THIS SECONDARY FRONT WILL INCREASE THE POST-FRONTAL NW FLOW TO 20-25 KT ACROSS THE DISCUSSION AREA N OF 30N W OF 138W ON SUN...WITH COMBINED SEAS BUILDING TO 12 FT NEAR 32N140W. EXPECT THE OCCLUDED LOW TO MEANDER NEAR 31N134W ON TUE WITH A WEAKENING FRONTAL TROUGH EXTENDING SSW TO NEAR 22N137W...WITH ASSOCIATED WINDS DIMINISHING TO 15-20 KT...AND SEAS SUBSIDING BELOW 8 FT W OF THE DISSIPATING FRONT BY MID WEEK. GULF OF TEHUANTEPEC...EXPECT TONIGHTS MAXIMUM DRAINAGE TO PEAK AT 20 KT AND THEN A MAX OF 15 KT ON SUN...MON AND TUE NIGHT. GUIDANCE IS SUGGESTING THE NORTHERLY FLOW WILL INCREASE TO 20-25 KT LATE WED NIGHT. $$ NELSON