624 AXPZ20 KNHC 010921 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 636 UTC Mon Oct 1 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 FEATURES... Rosa was downgraded to tropical storm status at 01/0000 UTC. At 01/0900 UTC, Rosa is centered near 26.7N 117.0W or 120 nm (225 km) WSW of Punta Eugenia, Mexico moving NE at 10 kt. Estimated minimum central pressure is 994 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Numerous moderate convection is noted between 60 nm and 180 nm NE quadrant of center. On the forecast track, the center of Rosa will approach the central and northern Baja California peninsula later today and then move across the peninsula into the northern Gulf of California tonight. Rosa's remnants are then expected to move across the Desert Southwest on Tuesday. Currently, heavy rain associated with Rosa continue to spread northward across northern Baja california into the extreme SW of United States. Swells generated by Rosa will affect portions of the coasts of southwestern Mexico, most of the west coast of the Baja California peninsula, and southern California through Tuesday. These swells are likely to cause life- threatening surf and rip current conditions. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 KNHC for more details. Farther south, Tropical Storm Sergio is centered near 11.5N 108.6W at 01/0900 UTC or 510 nm (950 km) SSW of Manzanillo Mexico, moving W at 12 kt, and this general motion is forecast to continue through tonight. A turn toward the west-northwest is expected on Tuesday. Estimated minimum central pressure is 995 mb. Maximum sustained wind speed is 60 kt with gusts to 75 kt. Strengthening is forecast during the next 48 hours, and Sergio is expected to become a hurricane later today, and a major hurricane by Wednesday morning. Currently, numerous moderate to strong convection is noted within 120 nm NW semicircle of center. Numerous moderate to isolated strong convection is seen in bands to the SE and NW of the center. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 KNHC for more details. ...TROPICAL WAVES... A tropical wave extends along 99W north of 04N into the State of Guerrero, Mexico. scattered moderate isolated strong convection is along the wave axis from 13N to 14N between 98W and 100W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 06N76W to 09N90W to 09N101W. Another segment of the monsoon trough reaches from 13N124W to 10N140W. Scattered moderate convection is noted from 06N to 10N between 80W and 90W, and from 06N to 09N between 94W and 99W. Similar convection is noted from 10N to 13N between 125W and 131W. A cluster of moderate to isolated strong convection is N of 14N between 92W and 95W. This convective activity is affecting the eastern part of the Gulf of Tehunatepec. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features above for information on Hurricane Rosa and Tropical Storm Sergio. Swell associated with Rosa will continue to propagate across the offshore forecast waters W of Baja California. Seas in the form of mixed swell in excess of 8 ft are observed from 20N to 30N between 110W and 123W. Another area of seas to 8 ft in mixed swell is from 12N to 20N between 118W and 125W. In the Gulf of California, the southerly flow will increase to near gale force N of 27N today, with seas building to around 10 ft late today north of Tiburon Island. Tropical storm conditions from Rosa are possible across the northern Gulf of California today and tonight. Winds and seas will diminish rapidly thereafter over the northern Gulf of California through late Tue. In the Gulf of Tehuantepec, pulsing winds of 20 to 30 kt are expected during the overnight and early morning hours through at least early Wed morning. Seas are forecast to build to 9 or 10 ft with the strongest winds. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The monsoon trough will meander between 09N and 12N through Fri, with gentle to moderate winds expected on either side of the trough axis. Moderate to fresh E nocturnal drainage flow is expected in the Gulf of Papagayo through tonight. An earlier scatterometer pass indicates easterly winds of 20 kt in the Gulfs of Papagayo and Fonseca. These winds will persist through early this morning, with winds less than 20 kt thereafter. REMAINDER OF THE AREA... See Special Features above for information on Hurricane Rosa and Tropical Storm Sergio. A pre-frontal trough extends 30N130W to 23N140W. A cold front follows the trough and stretches from 31N134W to 26N140W. A weak ridge is seen between Rosa and the trough covering mainly the waters N of 20N W of 125W. This weather pattern will keep the trade wind flow minimal farther south into the deep tropics. NW swell in the wake of the front will propagate across the NW waters through Tue, while seas associated with Rosa will subside to less than 8 ft W of the Baja California Peninsula. Later in the week, seas associated with Sergio will mix with additional pulses of long period NW swell. By Thu, seas of 8 ft or greater are expected to cover most of the waters N of 10N W of 105W, including the entrance of the Gulf of California. $$ GR