000 AXPZ20 KNHC 192136 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sat Aug 19 2023 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 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 2040 UTC. ...SPECIAL FEATURES... Hurricane Hilary is centered near 23.8N 114.1W at 19/2100 UTC, moving north-northwest at 15 kt. Estimated minimum central pressure is 959 mb. Maximum sustained wind speed is 95 kt with gusts to 115 kt. Scattered moderate to strong convection is within 180 nm in the eastern semicircle, and scattered moderate convection is within 270 nm in the western semicircle. Seas in excess of 12 ft extend to 330 nm in the NE quadrant and to 390 nm in the SE quadrant and to 330 nm in the SW quadrant and to 270 nm in the NW quadrant of the center, including within the southern Gulf of California. Hilary will maintain hurricane strength as it moves along the west coast of Baja California, before diminishing to tropical storm strength once it moves inland over Baja California Norte on Sun. Hilary is expected to produce storm total rainfall amounts of 3 to 6 inches, with isolated maximum amounts up to 10 inches, across portions of the northern Baja California Peninsula through Sunday night. Flash and urban flooding, locally catastrophic, is expected, especially in the northern portions of the peninsula. Heavy rainfall is expected across the Southwestern United States, peaking late tonight through Sunday night. Rainfall amounts of 3 to 6 inches, with isolated amounts of 10 inches, are expected across portions of southern California and southern Nevada. Dangerous to catastrophic flooding is expected. Elsewhere across portions of the Western United States, rainfall totals of 1 to 3 inches are expected, resulting in localized significant flash flooding. Large swells generated by Hilary are ongoing this afternoon across the outer and near shore waters of central and southern Baja California. These large swells will continue to affect portions of the Baja California Peninsula and southern California over the next couple of days, likely causing tremendous surf heights and life-threatening rip current conditions. Please consult products from your local weather office. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml and the latest Hilary NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... A small segment of an Atlantic tropical wave is along 82W, extending south from the coast of Panama to 06N. Scattered moderate convection is from 03N to 08N between 78W and 84W. A tropical wave is along 100W north of 03N moving west at 10-15 kt. Scattered moderate convection is from 10N to 15N between 90W and 102W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N84W to 08N106W and from 12N119W to 08N140W. Aside from the convection described in the tropical waves section, scattered moderate convection is from 08N to 11N between 117W to 125W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for information on Hurricane Hilary. Outside of Hurricane Hilary, satellite wind observations this afternoon depicted a small area of northerly gap winds of 15-20 kt in the Gulf of Tehuantepec. Gentle to moderate E to NE winds and seas of 4-7 ft prevail elsewhere. Active convection described above covers a large area between the Gulf of Tehuantepec and 103W, associated with the tropical wave along 100W. For the forecast, winds and seas will gradually diminish over Mexican offshore waters Sun through Mon in the wake of Hilary. Fresh to strong gap winds will pulse across the Gulf of Tehuantepec through mid week, mainly at night. Looking ahead, another area of low pressure has a low chance of development off southern Mexico through mid-week. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh NE to E winds are pulsing across the Papagayo region, with seas to 6 ft. Gentle winds are noted elsewhere, with mostly 3 to 5 ft seas in S to SW swell. For the forecast, moderate to fresh E winds will pulse at night across the Gulf of Papagayo region through Tue. Light to gentle breezes and slight to moderate seas will persist elsewhere through tomorrow. SW to W monsoonal winds will increase S of 09N beginning tonight between Colombia and waters north of the Galapagos, then increase offshore of Costa Rica and western Panama Mon and Tue, then diminish late Wed and Thu as the monsoon trough lifts northward. ...REMAINDER OF THE AREA... Recent scatterometer data captured fresh to locally strong SW winds from 07N to 11N between 110W and 122W flowing towards Hilary. Seas in this area of winds peak to 8 ft. A ridge dominates remaining waters north of 20N and west of 120W, supporting gentle to moderate winds with 5-7 ft seas. For the forecast, SW winds will start to increase south of the monsoon trough east of 110W Mon and Tue with building seas. $$ Mahoney/Stripling