000 AXPZ20 KNHC 181602 TWDEP TROPICAL WEATHER DISCUSSION NWS NATIONAL HURRICANE CENTER MIAMI FL 1605 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 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH 1545 UTC. ...SPECIAL FEATURES... HURRICANE OLAF IS CENTERED NEAR 9.5N 133.2W AT 1500 UTC MOVING WEST OR 275 DEGREES AT 10 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 989 MB. THE MAXIMUM SUSTAINED WIND SPEED IS 70 KT WITH GUSTS TO 85 KT. LATEST SATELLITE IMAGERY REVEALS AN INTENSIFYING CYCLONE WITH BANDING FEATURES RAPIDLY BECOMING WELL DEFINED PRIMARILY OVER THE SOUTHERN AND WESTERN SEMICIRCLE. A CDO (CENTRAL DENSE OVERCAST) FEATURE IS NICELY DEPICTED IN THE IMAGERY AS WELL. NUMEROUS MODERATE TO STRONG CONVECTION IS WITHIN 60 NM OF THE CENTER...EXCEPT WITHIN 75 NM OF THE CENTER IN THE SE QUADRANT. SIMILAR ACTIVITY IS ALSO WITHIN 60 NM OF A LINE FROM 07N133W TO 08N134W...AND WITHIN 45 NM OF A LINE FROM 08N134W TO 09N136W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IN BANDS IS PRESENT ELSEWHERE FROM 05N-12N BETWEEN 128W-136W...FROM 04N-07N BETWEEN 136W-138W...AND WITHIN 30 NM OF A RATHER LONG BAND THAT EXTENDS FROM 12N136W NE AND E TO 14.5N132W TO 15N129W TO 16N127W. SIMILAR ACTIVITY IS WITHIN 30 NM OF 13N135W...A OLAF IS FORECAST TO CONTINUE TO INTENSIFY OVER THE NEXT COUPLE OF DAYS AS IT MOVES W-NW ACROSS WARM WATERS AND THROUGH A GENERALLY LOW SHEAR ENVIRONMENT. OLAF IS EXPECTED TO REACH MAJOR HURRICANE INTENSITY ON 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 BY EARLY THIS AFTERNOON WHEN THE NOCTURNAL DRAINAGE FLOW DISSIPATES. HOWEVER...WINDS TO NEAR GALE FORCE SHOULD PERSIST THROUGH EARLY ON TUE AND MAY BE MORE ASSOCIATED WITH LOW PRESSURE PRESENTLY ALONG THE MONSOON TROUGH NEAR 13N94W AS DESCRIBED IN LAST PARAGRAPH. MAXIMUM SEAS OF 10-13 FT ARE EXPECTED TO CHANGE LITTLE THROUGH THE DURATION OF THIS EVENT. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... THE MONSOON TROUGH AXIS EXTENDS FROM 14N92W TO LOW PRES NEAR 13N94W 1007 MB TO 11N97W TO 13N105W TO LOW PRES NEAR 09N113W 1007 MB TO 11N120W. NUMEROUS MODERATE TO STRONG CONVECTION IS SEEN FROM 11N-15N BETWEEN 95W-99W. SCATTERED MODERATE/ISOLATED STRONG CONVECTION IS FROM 11N-14N BETWEEN 88W-93W. ...DISCUSSION... THE ATMOSPHERE REMAINS QUITE DRY AND STABLE N OF ABOUT 17N AS OBSERVED BY THE AMPLE SUBSIDENCE THERE ON WATER VAPOR IMAGERY. S OF THE 17N...THE IMAGERY SHOWS A VERY MOIST ATMOSPHERIC ENVIRONMENT EXCEPT BETWEEN 109W-118W WHERE RELATIVELY DRIER AIR IS IN PLACE...AND ONLY ISOLATED SHOWERS AND TSTMS ARE NOTED THERE. A STATIONARY SUBTROPICAL 1024 MB HIGH CENTER IS NEAR 34N140W WITH A RIDGE SE TO 27N128W AND TO NEAR 23N118W. THE PRESSURE GRADIENT BETWEEN THE HIGH TO THE N AND HURRICANE OLAF TO THE S IS BRINGING MODERATE TO FRESH TRADE WINDS OVER MUCH OF THE WESTERN PORTION OF THE DISCUSSION AREA. SEAS TO 9 FT IN NW SWELL IN THE WAKE OF A PREVIOUSLY DISSIPATED COLD FRONT ARE TO THE NW OF A LINE FROM 32N128W TO 14N140W. THE SWELL WILL CONTINUE TO PROPAGATE SOUTHWARD...MERGE WITH THE SWELL FROM OLAF...AND EASTWARD COMBINING WITH AN AREA OF SHORTER PERIOD N-NW SWELL EXPECTED FROM WINDS OFF THE CALIFORNIA COAST MON AND TUE. THE AFOREMENTIONED RIDGE WILL STRENGTHEN THROUGH TUE...AND HELP TO EXPAND THE AREA OF 20-33 KT WINDS N OF OLAF. LONG PERIOD SW SWELL WITH PERIODS IN THE 19-21 SECOND RANGE HAS REACHED THE MEXICAN PACIFIC COAST NEAR MAZATLAN...AND IS FORECAST TO CONTINUE TO PROPAGATE NE TO THE PACIFIC COAST OF THE BAJA CALIFORNIA PENINSULA THIS AFTERNOON. 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 7-8 FT SEAS CURRENTLY WITHIN 60 NM OF LINE FROM 07N98W TO 05N105W TO 01N110W. THESE SEAS ARE EXPECTED TO SUBSIDE WITHIN THE NEXT 36-48 HOURS. BY 48 HOURS...AN AREA OF SEAS TO 8 FT PRIMARILY IN SW SWELL IS FORECAST FROM 05N-08N BETWEEN 99W-104W. 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 13N94W. IT IS POSSIBLE THAT THIS LOW COULD BECOME A TROPICAL CYCLONE AROUND MID-WEEK. 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 SOUTHEASTERN MEXICO THROUGH THE REMAINDER OF THE WEEKEND INTO EARLY NEXT WEEK. $$ AGUIRRE