000 AXPZ20 KNHC 102146 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Oct 10 2018 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...SPECIAL FEATURE... Tropical Storm Sergio centered near 18.6N 123.0W at 10/2100 UTC or 770 nm W-SW of the southern tip of Baja California moving NE at 11 kt. Estimated minimum central pressure is 992 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered strong convection is noted in bands within 210 nm northeast and 120 nm southwest semicircles of center. Large swells associated with Sergio will continue to mix with long period NW swell, and long period cross-equatorial southwest swell, creating confused seas across a large portion of the discussion waters, generally west of 100W. This swell will continue to impact the Pacific coast of Mexico through early Fri. Refer to the NHC forecast/advisory under AWIPS/WMO headers MIATCPEP1/WTPZ31 KNHC for additional details. ...TROPICAL WAVE... A broad tropical wave has been re-positioned north of 08N along 78W and is moving slowly westward. Scattered moderate isolated strong convection iS observed to the north of 05N AND EAST OF 85W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends southwest off the Pacific coast of Mexico at 16N97W to 12N113W where it loses identity in the broad cyclonic circulation associated with Tropical Cyclone Sergio. Scatterometer winds indicate the monsoon trough resumes southwest of Sergio at 13N129W and continues southwest to beyond 10N140W. Scattered moderate isolated strong convection is observed along the monsoon trough within 150 nm either side of a line from 13N93W to 15N97W to 06N111W with this convection extending about 120 nm inland Mexico from 92W to 100W. Similar convection is noted within 60 nm either side of a line from 10N123W to 09N140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features paragraph above for information on Tropical Cyclone Sergio. West of the Baja California Peninsula...light to moderate southeast winds are observed with southerly swell from Sergio mixing with long period northwest swell, resulting in 6 to 9 ft seas throughout. The swell component from Sergio will continue to increase ahead of tropical storm conditions arriving 250 nm seaward on Thu morning with seas 12 ft or greater reaching most of the west coast of Baja on Thu evening. These large seas will result in hazardous marine conditions through late Fri. Expect seas to subside below 8 ft around sunrise on Sat. Gulf of California: Light and variable winds will gradually become a fresh southerly breeze on Thu evening and increase to a strong to near gale force breeze across the central gulf waters Thu night, with tropical storm conditions and seas to perhaps 13 ft, by early Fri. Moderate northwest flow expected by late Fri night as Sergio continues further inland. Farther south, moderate to fresh westerly flow, and 6 to 9 ft seas are forecast through late Fri. Model guidance is hinting at a surface low developing just southwest of the Gulf of Tehuantepec on Fri night, with the low moving northwest to near 16N103W by early Mon accompanied by fresh winds and seas to about 12 ft. This low will do little to interrupt the persistent moist southwesterly flow along the southwest coast of Mexico, with coastal convection likely to continue through the upcoming weekend. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh moist southwesterly monsoonal flow will continue across the area through the upcoming weekend with convection likely to continue along the Pacific coast of Central America. Long period cross equatorial southwest will maintain mainly 5 to 7 ft seas, with 7 to 9 ft conditions in the small areas of fresh to locally strong winds. REMAINDER OF THE AREA... See the Special Features paragraph above for information on Tropical Cyclone Sergio. Confused seas generated from Sergio will subside from the west through Sat as the pressure gradient relax across the discussion waters north of 20N and west of 120W. A cold front will approach the northwest portion on Mon night. $$ Nelson