000 AXPZ20 KNHC 170339 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Aug 17 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...SPECIAL FEATURES... Tropical Storm Hilary is centered near 13.4N 105.1W at 17/0300 UTC, moving west-northwest at 10 kt. Estimated minimum central pressure is 996 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Numerous moderate to strong convection covers the area from 10N to 15N between 101W and 108W. Peak seas are 24 ft with the 12 ft seas extending within 270 nm in the NE quadrant, 240 nm in the SE quadrant, 105 nm in the SW quadrant, and 150 nm in the NW quadrant. Seas are expected to become high to very high during the next 36-48 hours, with an extensive are of seas greater than 8 ft. Hilary will continue to move west- northwest with a gradual turn to the northwest by Friday followed by a turn to the north- northwest on Saturday. Rapid intensification is forecast over the next 24-36 hours, and Hilary is forecast to become a major hurricane by the end of the week. Large swells generated by Hilary will affect portions of the coast of southwestern Mexico and the Baja California peninsula over the next few days. These swells are likely to cause life- threatening surf and rip current conditions. Interests in Baja California Sur should closely monitor the progress of this system. Watches will likely be required for a portion of that area as soon as tomorrow morning. 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 Fernanda NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Tropical Storm Fernanda is centered near 16.7N 129.4W at 17/0300 UTC, moving west at 13 kt. Estimated minimum central pressure is 1002 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Scattered moderate convection is noted in the western semicircle from 16N to 18N between 130W and 132W. Peak seas are around 20 ft with the 12 ft seas extending 120 nm in the NE quadrant, 105 nm in the SE quadrant, and 90 nm in the west semicircle. Continued weakening is forecast during the next couple of days, and Fernanda is likely to become a post-tropical cyclone tonight or Thursday and dissipate by the weekend. It will continue moving westward for the next few days. Seas will drop below 12 ft by Fri night as Fernanda approaches 140W. 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 Fernanda NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... A tropical wave is along 90W from 05N northward to across Guatemala. the coast of El Salvador, moving W at 10 to 15 kt. Scattered moderate to isolated strong convection is noted from 04N to 10N between 85W and 92W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N84W to 07N90W to 11N97W then continues W of T.S. Hilary from 13N113W to 12N125W to 08N135W. The ITCZ stretches to beyond 07N140W. Scattered moderate to isolated strong convection is noted from 04N to 08N between 79W and 87W. Scattered moderate to isolated strong convection is noted from 04N to 10N between 85W and 92W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features for information on Tropical Storm Hilary. Outside of TS Hilary, a surface ridge dominates the offshore forecast waters of Baja California. This is causing moderate NW to N winds off Baja California Norte, with light to gentle winds elsewhere in the Baja California offshore waters. Seas are 4 to 6 ft in mixed swell. In the Gulf of California, light to gentle winds are noted with seas of 1 to 2 ft, except seas of 3 to 4 ft near the entrance to the Gulf. Light to gentle winds are elsewhere off the southern Mexico offshore waters with 4-6 ft seas in mostly SW swell. For the forecast, Tropical Storm Hilary will move to 14.3N 106.9W Thu morning, strengthen to a hurricane near 15.5N 109.1W Thu evening, 16.8N 111.0W Fri morning, 18.5N 112.5W Fri evening, 20.5N 113.4W Sat morning, and 22.6N 114.0W Sat evening. Hilary will weaken to a tropical storm near 28.3N 115.4W late Sun. Looking ahead, an area of low pressure could form south of the Gulf of Tehuantepec over the weekend. Some gradual development of this system is possible thereafter while it moves generally west-northwestward. This system has a low chance of tropical cyclone development over the next 48 hours and 7 days. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to locally strong winds are seen in the Papagayo region, and downwind to near 88W. Seas range 5 to 8 ft in this area. Moderate southerly winds are noted off the Ecuador coast with light to gentle winds elsewhere across the Central America and South American offshore waters. Seas are generally 4 to 6 ft due to long-period SW swell, except 1 to 3 ft in the Gulf of Panama, and 3 to 5 ft just offshore Colombia. For the forecast, fresh to locally strong winds are expected in the Papagayo region trough Sun night. Winds will increase to moderate between Ecuador and the the Galapagos Islands waters tonight and will persist through the weekend. Expect moderate seas within S to SW swell in this area. ...REMAINDER OF THE AREA... Please refer to the Special Features section above for details on Tropical Storm Fernanda. A ridge dominates roughly the waters N of 20N and W of 115W. The pressure gradient between the ridge and tropical cyclone Fernanda supports an area of moderate to fresh winds from 15N to 22N between 125W and 135W. Light to gentle winds are noted elsewhere under the influence of the ridge. Gentle to locally moderate S to SW winds are noted S of the ITCZ/monsoon trough. Seas range 4-7 ft across the forecast waters within NW swell. For the forecast, based on latest NHC forecast advisory, Fernanda will become post-tropical and move to 16.6N 131.4W Thu morning, weaken to a remnant low near 16.5N 134.0W Thu evening, 16.5N 136.5W Fri morning, 16.5N 139.1W Fri evening, 16.5N 141.7W Sat morning, and dissipate Sat evening. $$ GR