000 AXPZ20 KNHC 042216 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Thu Oct 4 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 2100 UTC. ...SPECIAL FEATURES... Major Hurricane Sergio is centered near 15.5N 119.9W 947 MB AT 2100 UTC, or about 720 nm SW of the southern tip Baja California, moving NW at 8 kt. Maximum sustained winds are 115 kt with gusts to 140 kt. Little change in intensity is expected during the next 6-12 hours as Sergio continues to move NW. Sergio is then expected to move WNW late tonight and then veer more westward through the weekend, and will likely diminish gradually in intensity as it begins to move over slightly cooler waters. Numerous strong convection is seen on satellite imagery this afternoon within 90 nm E and 120 nm W semicircles, while additional bands of scattered moderate to strong convection are occurring elsewhere within 120 nm NW and 180 nm SE semicircles. Large swell generated from Sergio will impact the Pacific coasts of Mexico and southern California during the remainder of this week. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from low pressure along the NE Honduras coast near 15.5N83W to developing low pressure near 10.5N87W to 14N104W, then resumes SW of Sergio from 10N123W to 12N130W to beyond 10N140W. Scattered strong convection is from 06N to 12N between 82W and 91W. Scattered moderate to strong convection is within 150 nm N and 210 nm S of trough between 94W and 98W, and from 08N to 12.5N between 130W and 141W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features above for information on the impacts of Hurricane Sergio. A weakening frontal trough extends from offshore of central California through 30N123W to 22.5N135W. The trough will continue to move eastward and become diffuse by the time it reaches the Baja Peninsula on Fri. High pressure building SE behind the boundary will freshen NW winds across the offshore waters of Baja California this evening, with building seas in NW swell. A strong surge of southerly swell from Sergio is moving into the area waters today, and was depicted by an early morning altimeter pass with 6-11 ft seas across the waters from Manzanillo to Cabo San Lazaro along Baja California Sur. Expected building seas to continue across the entire area through tonight, peaking at 8-12 ft, and impacting the entrance of the Gulf of California. Large and dangerous surf will dominate the coastal zones into the weekend, including the southern the Gulf of California. Gentle to moderate NW to W winds prevailing across most of the Gulf of California today will freshen this evening as high pressure builds across the area tonight through Sat morning. A strong frontal system will move into central California Sat and induce a wind shift to SW to S across the Gulf late Sat and Sun. Winds will increase to 20-25 kt across the far N portions of the Gulf Sat night, with gusts to 30 kt possible. Moderate NW winds will generally prevail across the waters between Cabo San Lucas and the Gulf of Tehuantepec for the next few days, while large SE swell from Sergio dominates area seas. In the Gulf of Tehuantepec, offshore northerly gap winds of 20 to 25 kt are expected to pulse to near 30 kt late tonight and then slowly diminish through Sat. Broad low pressure will extend from the Yucatan Peninsula to SE Mexico and the Pacific waters by Sun and produce a pattern change to NW to W winds across the Gulf. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The monsoon trough will meander between 09N and 12N, with fresh to strong southwesterly flow and building seas to 10 ft expected S of the monsoon trough E of 100W through Sat, as a broad low pressure area develops across the western Caribbean and Central America. This broad area of low pressure and the associated long fetch of SW winds across the tropical Pacific will transport abundant moisture into portions of Costa Rica, Nicaragua, and western Panama, and will produce significant rainfall through early next week. Isolated areas could see 20 inch rainfall accumulations by Mon. Refer to your local meteorological service for specific information on this potentially dangerous pattern. REMAINDER OF THE AREA... See Special Features above for information on Hurricane Sergio. As mentioned above, a frontal trough across the northern waters will gradually become diffuse during the next 24 hours, as it sweeps eastward across Baja California Norte early Fri. NW swell behind the trough will combine with fresh NE winds to build seas to 9-10 ft this evening and tonight, then merge with the large and growing area of mixed swell associated with Hurricane Sergio on Fri. Southerly swell from Sergio will mix with NW swell through the weekend to maintain seas in excess of 10 ft Sun and Mon. $$ Stripling