000 AXPZ20 KNHC 110950 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 816 UTC Thu Oct 11 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURE... Tropical Storm Sergio centered near 21.0N 120.2W at 11/0900 UTC or 580 nm W of the southern tip of Baja California moving NE at 15 kt. Estimated minimum central pressure is 992 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered moderate to isolated strong convection is noted within 180 nm in the north semicircle from the center, with scattered moderate convection within 120 nm in the south semicircle. 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. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends southwest off the Pacific coast of Mexico at 16N98W to 11.5N110W to 13N115W. Another segment of the monsoon trough reaches from 13N127W to 10N135W to beyond 10N140W. Scattered moderate convection is observed from 12N to 14N between 92W and 100W, and from 08N to 10N between 135W and 138W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features paragraph above for information on Tropical Storm 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 region. The swell component from Sergio will continue to increase ahead of tropical storm conditions arriving 250 nm seaward later in the morning with seas 12 ft or greater reaching most of the west coast of Baja by evening. These large seas will result in hazardous marine conditions through late Fri. Expect seas to subside below 8 ft early Sat. Gulf of California: Fresh SW gap winds were noted on a recent scatterometer pass pushing into the northern Gulf of California near Isla San Luis. These winds will diminish through the morning as Sergio approaches. Elsewhere light and variable winds will gradually become a fresh southerly breezes by evening and increase to a strong to near gale force breezes across the central gulf waters by late tonight, with tropical storm conditions and seas to perhaps 13 ft, by early Fri. Moderate W to NW 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 early next week accompanied by fresh winds and seas to 9 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 swell will maintain mainly 5 to 7 ft seas, with 7 to 9 ft conditions in the small areas of fresh to locally strong winds. Looking ahead to early next week, global models are indicating development of broad low pressure over the southwest Caribbean, possibly becoming another Central American gyre next week. This may enhance showers and thunderstorms off Panama and Costa Rica Sun and Mon. 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 30N140W by late Mon. $$ Christensen