000 AXPZ20 KNHC 100900 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 900 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 0600 UTC surface analysis and satellite imagery through 0845 UTC. ...SPECIAL FEATURES... Tropical Storm Sergio centered near 17.5N 124.9W at 10/0900 UTC or 890 nm WSW of the southern tip of Baja California moving ENE at 10 kt. Estimated minimum central pressure is 991 mb. Maximum sustained wind speed is 60 kt with gusts to 75 kt. Numerous moderate and isolated strong convection is noted within 180 nm in the north semicircle, and 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 increasingly a component of SW swell, creating confused seas across a large portion of the discussion waters. The swell will continue to impact the coast of Mexico the next several days as Sergio makes its way to central Baja California Sur by Fri. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCPEP1/WTPZ31 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough reaches from Acapulco Mexico near 16N98W to 13N111W. Another segment of the monsoon trough extends from 13N130W to 10N140W. No significant convection is observed. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for details on T.S. Sergio. Recent altimeter satellite passes indicated 7 to 9 ft seas over the Pacific offshore areas of Baja California. This in a mix of southerly swell from Sergio, and longer period and decaying NW swell. These swell could create hazardous surf, as well as dangerous marine conditions near marinas and jetties, for Baja California and the Mexican coast between Manzanillo and Mazatlan. Conditions are forecast to rapidly deteriorate across the Baja California waters as Sergio moves closer on Thu. Conditions will then worsen for the central and northern Gulf of California Thu night and Fri. Winds and seas rapidly diminish Fri night and Sat as Sergio dissipates far inland. Farther south, the persistent fresh to occasionally strong SW flow has been supporting scattered moderate showers and thunderstorms extending around 400 nm W-SW of coast of southern Mexico. The SW flow is flowing across the Isthmus of Tehuantepec into the Gulf of Mexico where Hurricane Michael is active. As Michael moves northward and inland today, the fresh to occasionally strong SW flow over the eastern Pacific will diminish, although moderate SW flow persist through the remainder of the week in this area. Wave guidance suggests seas may be as high as 9 ft in the plume of persistent SW flow. These seas will subside gradually over the following couple of days. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please refer to the Special Features section for additional details regarding the heavy rainfall potential for Central America. Fresh SW monsoonal flow and 8 ft seas will persist off Guatemala through Wed night then conditions will diminish. Moderate SW flow will then continue through the week. Long period SW swell will continue to propagate from the Southern Hemisphere into the waters off southern Central America, with combined seas building to 5 to 7 ft off Panama and Costa Rica Thu, then to 8 to 9 ft Fri. REMAINDER OF THE AREA... Please see the Special Features section for details on Hurricane Sergio. Outside of the influence of Sergio, moderate to fresh trades will prevail. The pressure gradient will lessen across the waters north of 20N and west of 120W through the end of the week as high pressure centered NW of the discussion area weakens in response to low pres approaching from the west. Meanwhile, confused seas are likely to continue due to long period NW swell along with mixed shorter period swell generated from Sergio. Conditions are likely to improve by the end of the week after Sergio makes landfall. Long period SW swell arriving from the Southern Hemisphere will also contribute to combined seas and maintain sea heights between 8 and 9 ft along the equator between 100W and 130W through Fri. The swell will gradually decay and seas subside in this area into Sat. $$ Christensen