000 AXPZ20 KNHC 270250 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 0405 UTC TUE OCT 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 0200 UTC. ...SPECIAL FEATURES... TROPICAL STORM OLAF CONTINUES TO MOVE NORTHEASTWARD ACROSS NW PORTIONS OF THE DISCUSSION AREA TONIGHT...CENTERED NEAR 26.3N 137.4W AT 0300 UTC. ESTIMATED MINIMUM CENTRAL PRESSURE IS 995 MB. MAXIMUM SUSTAINED WIND SPEED IS 45 KT WITH GUSTS TO 55 KT. SEE THE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS. STRONG UPPER LEVEL SW WIND SHEAR ASSOCIATED WITH AN UPPER LEVEL TROUGH CONTINUES TO IMPACT OLAF TONIGHT...AND IS SHEARING OR DISPLACING THE ACTIVE CONVECTION TO THE NORTHEAST OF THE LOW LEVEL CENTER. THIS PROCESS IS ALSO BEGINNING TO STRETCH THE LOW LEVEL CIRCULATION E- NE TO S-SW. SCATTERED MODERATE CONVECTION WAS NOTED IN SATELLITE IMAGERY FROM 60 TO 360 NM ACROSS THE NE SEMICIRCLE...AND NO LONGER OVER THE CENTER. THE UNFAVORABLE UPPER LEVEL CONDITIONS ARE EXPECTED TO PERSIST ACROSS THE REGION FOR THE NEXT 24-48 HOURS...AND CONTINUE TO WEAKEN OLAF...AS IT MOVES NE AND GRADUALLY WEAKEN TO A TROPICAL DEPRESSION STORM NEAR 27.8N 133.8W BY 00 UTC WED...THEN BECOMES INVOLVED WITH AN APPROACHING COLD FRONT BY 48 HOURS...WHERE IT IS EXPECTED TO WEAKEN TO A 25 KT POST-TROPICAL REMNANT LOW NEAR 26.1N 135.3W. THE COLD FRONT WILL MOVE INTO THE NW CORNER OF THE AREA FROM 30N137W TO 26N140W BY TUE EVENING...WHERE IT WILL STALL THROUGH LATE WED. LARGE NORTHWEST SWELL GENERATED BEHIND THIS COLD FRONT WILL MERGE WITH THE SWELL AND WAVES FROM OLAF IN THE NEXT 48 HOURS TO MAINTAIN HIGH SEAS ACROSS NW PORTIONS IN THE 10-15 FT RANGE. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH EXTENDS FROM 09.5N73W TO 11N86W TO 09.5N95W TO 14.5N108W TO LOW PRES NEAR 12.5N126.5W TO 08.5N132W TO BEYOND 07.5N140W. SCATTERED MODERATE TO STRONG CONVECTION NOTED WITHIN 240 NM N AND 360 NM S OF TROUGH E OF 104W...AND WITHIN 270 NM S OF TROUGH W OF 125W. ...DISCUSSION... NORTHERLY GALES BLOWING ACROSS THE GULF OF TEHUANTEPEC AND DOWNSTREAM TO NEAR 13.5N96W HAVE DIMINISHED TO 20-30 KT THIS EVENING...WITH SEAS SUBSIDING SLIGHTLY TO 8-11 FT. STRONG NORTHERLY WIND FLOW ACROSS THE W GULF OF MEXICO THE PAST 24 HOURS HAD BEEN DRIVING THE GALES ACROSS TEHUANTEPEC...BUT WINDS HAVE DIMINISHED CONSIDERABLY ACROSS THE GULF OF MEXICO DURING THE PAST 6 HOURS. NORTHERLY WINDS ACROSS THE GULF OF TEHUANTEPEC WILL HOLD AT 20-25 KT OVERNIGHT DUE TO NOCTURNAL DRAINAGE...THEN FALL BELOW 20 KT BY TUE AFTERNOON...WITH SEAS SUBSIDING TO LESS THAN 8 FT BY LATE AFTERNOON. N OF 15N E OF OLAF...A FAIRLY WEAK PRESSURE GRADIENT REMAINS IN PLACE OVER THE REGION BETWEEN 1017 MB HIGH PRES CENTERED NEAR 33N126W AND BROAD SURFACE TROUGHING OVER NW MEXICO. RECENT SHIP OBSERVATIONS AND SCATTEROMETER DATA INDICATE GENERALLY LIGHT TO MODERATE NW FLOW PERSISTING OFF THE W COAST OF BAJA CALIFORNIA AND GULF OF CALIFORNIA. SEAS HAVE SUBSIDED ACROSS THE GULF OF CALIFORNIA TO 3 FT OR LESS W OF 110W...AND 4-5 FT IN SE-S SWELL NEAR THE ENTRANCE TO THE GULF. A WEAK MID/UPPER LEVEL SHORT WAVE TROUGH MOVING EASTWARD ACROSS THE REGION TONIGHT WILL BE FOLLOWED BY ANOTHER WEAK MID/UPPER TROUGH TUE INTO WED...KEEPING THE RELATIVELY TRANQUIL MARINE CONDITIONS IN PLACE. LOOKING AHEAD...A STRONGER MID/UPPER TROUGH WITH AN ASSOCIATED COLD FRONT WILL APPROACH THE AREA LATE IN THE WEEK. THIS WILL BRING STRONG NORTHERLY FLOW TO THE WATERS NORTH OF GUADALUPE ISLAND...ALONG WITH A NEW ROUND OF LONG PERIOD NW SWELL WITH WAVE HEIGHTS 8 TO 10 FT TO THE BAJA COAST BY LATE THU. S OF 15N E OF 130W...A MONSOONAL CIRCULATION CONTINUES TO DOMINATE THE TROPICS...TRANSPORTING TROPICAL MOISTURE E AND NE TO SW MEXICO AND CENTRAL AMERICA. WEAK LOW PRES WILL CONTINUE TO OCCASIONALLY FORM ALONG THE MONSOON TROUGH NEAR 90W W OF COSTA RICA...BUT WILL REMAIN ELONGATED MAKING IT DIFFICULT TO DEPICT AS A DISTINCT LOW CENTER. NO SIGNIFICANT DEVELOPMENT IS ANTICIPATED THROUGH THE NEXT 48 HOURS. RESIDUAL SW SWELL IS MAINTAINING SEAS OF 5 TO 8 FT OVER MUCH OF THE AREA. ELSEWHERE...A 1009 MB LOW PRES IS ANALYZED NEAR 12.5N126.5W EMBEDDED ALONG THE MONSOON TROUGH. EARLIER SCATTEROMETER DATA INDICATED MODERATE TO FRESH WINDS WITHIN 120 NM ON THE NW SIDE OF THE LOW WHERE RESULTANT SEAS ARE UP TO 8 FT. LITTLE CHANGE IS ANTICIPATED IN THE INTENSITY OF THE LOW PRES THROUGH THE NEXT SEVERAL DAYS AS IT DRIFTS NW...WITH A LINGERING PATCH OF FRESH WINDS AND SEAS TO 8 FT PERSISTING THROUGH TUE NIGHT. SEAS WILL INCREASE HOWEVER BY LATE WEEK WITH THE ADDITION OF LONG PERIOD NW SWELL INTO THIS AREA. $$ STRIPLING