000 AXPZ20 KNHC 180930 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1005 UTC SUN OCT 18 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 0600 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 0830 UTC. ...SPECIAL FEATURES... HURRICANE OLAF WAS CENTERED NEAR 9.4N 131.9W AT 0900 UTC MOVING WEST OR 275 DEGREES AT 8 KT. ESTIMATED MINIMUM CENTRAL PRESSURE WAS 991 MB. THE MAXIMUM SUSTAINED WIND SPEED WAS 65 KT WITH GUSTS TO 80 KT. NUMEROUS MODERATE TO STRONG CONVECTION WAS WITHIN 30 NM OF CENTER...EXCEPT 90 NM S QUADRANT. SCATTERED MODERATE WITH ISOLATED STRONG CONVECTION WAS ELSEWHERE FROM 04N- 12N BETWEEN 128W-136W. OLAF IS FORECAST TO CONTINUE TO INTENSIFY AS IT MOVES W-NW OVER THE NEXT COUPLE OF DAYS...AND IS EXPECTED TO REACH MAJOR HURRICANE STRENGTH MON. PLEASE SEE LATEST FORECAST ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP4/WTPZ24 KNHC FOR MORE DETAILS ON OLAF. GULF OF TEHUANTEPEC...WINDS OF MINIMAL GALE FORCE CONTINUE TO FUNNEL THROUGH THE CHIVELA PASS AND INTO THE GULF OF TEHUANTEPEC THIS MORNING. THE GALE WARNING IS SET TO EXPIRE AFTER SUNRISE TODAY WHEN THE NOCTURNAL DRAINAGE FLOW DISSIPATES. HOWEVER... WINDS TO NEAR GALE FORCE SHOULD PERSIST THROUGH THE END OF THE FORECAST PERIOD EARLY TUE MORNING. MAXIMUM SEAS OF 10-13 FT ARE EXPECTED WITH THIS EVENT. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS WAS ANALYZED FROM 14N92W TO LOW PRES NEAR 12N94W 1007 MB TO 11N97W TO 13N105W TO LOW PRES NEAR 09N113W 1007 MB TO 11N120W. NUMEROUS MODERATE TO STRONG CONVECTION WAS FROM 10N-14N BETWEEN 87W-93W AS WELL AS N OF 10N BETWEEN 94W-103W. ...DISCUSSION... A DISSIPATING STATIONARY FRONT WAS ANALYZED FROM NEAR 32N122W TO 27N133W. A 1025 MB SUBTROPICAL HIGH PRES SYSTEM CENTERED NW OF THE AREA NEAR 34N142W LIES BEHIND THE FRONT. THE PRESSURE GRADIENT BETWEEN THE HIGH TO THE N AND HURRICANE OLAF TO THE S IS DRIVING MODERATE TO FRESH TRADE WINDS. THE STATIONARY FRONT SHOULD DISSIPATE BY SUNRISE TODAY. SEAS TO 9 FT IN NW SWELL NW OF A LINE FROM 30N129W TO 14N140W WILL CONTINUE TO PROPAGATE SOUTHWARD...MERGING WITH THE SWELL FROM OLAF...AND EASTWARD...MEETING UP WITH AN AREA OF SHORTER PERIOD N-NW SWELL EXPECTED FROM WINDS OFF THE CALIFORNIA COAST MON AND TUE. THE SUBTROPICAL RIDGE WILL BUILD OVER N WATERS ONCE THE FRONT DISSIPATES. THIS WILL HELP EXPAND THE AREA OF 20-33 KT WINDS N OF OLAF. SW SWELL WITH PERIODS IN THE 19-21 SECOND RANGE HAS REACHED THE PACIFIC COAST S OF CABO CORRIENTES MEXICO THIS MORNING. THE LEADING EDGE OF THE SWELL WILL REACH N TO MAZATLAN BY SUNRISE AND STRETCH ALONG THE PACIFIC COAST OF THE BAJA CALIFORNIA PENINSULA AFTER SUNRISE THIS MORNING. THIS LONG-PERIOD SWELL COULD MAKE FOR DANGEROUS CONDITIONS ENTERING AND EXITING PORTS AND WILL INCREASE THE THREAT OF RIP CURRENTS. THE SW SWELL IS CONTRIBUTING TO THE 7-9 FT SEAS CURRENTLY FOUND OVER MUCH OF THE AREA S OF 09N BETWEEN 90W AND 120W. COMBINED SEAS AT OR ABOVE 8 FT IN THIS SWELL W OF 100W WILL SUBSIDE TO S OF THE EQUATOR BY MON. A CENTRAL AMERICAN GYRE WILL HELP MAINTAIN THE WINDS OF NEAR GALE TO MINIMUM GALE FORCE OVER THE GULF OF TEHUANTEPEC THROUGH EARLY TUE. THE MONSOON TROUGH HAS BEEN LIFTED NORTHWARD OVER THE EASTERN PORTION OF THE BASIN AND SW MONSOONAL FLOW HAS INCREASED. THIS ENHANCED MONSOON FLOW CONTINUES TO ADVECT ABUNDANT TROPICAL MOISTURE INTO THE EASTERN WATERS AND PORTIONS OF CENTRAL AMERICA AND SOUTHERN MEXICO...WITH THE POTENTIAL FOR ACTIVE WEATHER REMAINING HIGH OVER THIS AREA FOR THE NEXT FEW DAYS. GLOBAL MODELS CONTINUE TO SUGGEST THAT THE INTERACTION OF THE TEHUANTEPEC GAP WINDS WITH THE MONSOON TROUGH WILL HELP TO DEEPEN THE 1007 MB LOW PRESSURE CENTER ANALYZED ALONG THE MONSOON TROUGH NEAR 12N94W. IT IS POSSIBLE THAT THIS LOW COULD BECOME A TROPICAL CYCLONE AROUND MIDWEEK. REGARDLESS OF TROPICAL CYCLONE FORMATION...THIS SYNOPTIC SETUP WILL BRING THE POTENTIAL FOR LOCALLY HEAVY RAINFALL WHICH MAY LEAD TO FLASH FLOODING AND DANGEROUS MUDSLIDES OVER PORTIONS OF CENTRAL AMERICA AND SOUTHERN MEXICO THROUGH THE REMAINDER OF THE WEEKEND INTO EARLY NEXT WEEK. $$ SCHAUER