000 AXPZ20 KNHC 180906 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Oct 18 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ...SPECIAL FEATURES... Tropical Storm Norma is centered near 14.2N 107.9W at 18/0900 UTC, moving northwest at 6 kt. Estimated minimum central pressure is 995 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Peak seas are currently around 20 ft. Numerous moderate isolated strong convection is noted from 12N to 17N between 105W and 111W. Scattered moderate and isolated strong convection is noted from 05N to 20N between 99W and 111W. Norma is moving toward the northwest, and a slow north- northwestward to northward track is forecast for the next 48 to 72 hours. There is a high likelihood for significant strengthening during the next 48 hours or so, and Norma is forecast to become a hurricane today. 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 Invest NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Gulf of Tehuantepec Gale Warning: The area of high pressure across the eastern slopes of Mexico that was responsible for the tight pressure gradient across the area has started to shift eastward, and the pressure gradient has started to loosen. An overnight ASCAT pass shows that the areal coverage of the gale force winds has decreased, and winds have diminished to 35 kt. Seas are currently peaking near 14 ft. Winds will further decrease today, and winds are forecast to diminish below gale- force by early this afternoon when seas will also likely subside below 12 ft. The pressure gradient will remain tight enough to support pulsing fresh to strong winds through the remainder of the week. Please read the latest NHC High Seas Forecast at website www.hurricanes.gov/marine for more details. NW Swell in the NW waters: Large NW swell has propagated into the NW waters. Seas of 12 ft have reached 30N140W. Seas greater than 12 ft will continue propagating SE, and will cover the waters N of 25N and W of 135W by early this afternoon. Seas will peak around 15 ft this afternoon into the evening near 30N140W. This swell will continue to spread SE with seas 8 ft or greater covering the majority of the waters W of 100W by the end of the week, when peak seas should subside to just below 12 ft. Seas will continue to gradually decay from west to east Fri night through the upcoming weekend. Please read the latest NHC High Seas Forecast at website www.hurricanes.gov/marine for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N85W to 10N100W. It resumes SW of Norma near 11N113W to 07N140W. Scattered moderate and isolated strong convection is noted from 04N to 12N between 83W and 90W. Scattered moderate convection is noted from 03N to 10N between 112W and 130W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the SPECIAL FEATURES section above for more details on Tropical Storm Norma, and the ongoing Gulf of Tehuantepec Gale Warning. Aside from Tropical Storm Norma and the Gulf of Tehuantepec Gale Warning, a ridge extends across the Baja California offshore waters. Gentle to moderate winds prevail west of the Baja California peninsula with light to gentle winds elsewhere offshore Mexico, including in the Gulf of California. Seas are in the 6-8 ft range offshore Baja California Norte, and 4-6 ft elsewhere over the open waters off Mexico. Seas of 1-2 ft are noted over the Gulf of California. For the forecast, Norma is near 14.2N 107.9W at 2 AM PDT, and is moving northwest at 6 kt. Maximum sustained winds are 55 kt with gusts to 65 kt, and the minimum central pressure is 995 mb. Norma will strengthen to a hurricane near 15.0N 108.1W this afternoon, move to 16.2N 108.3W Thu morning, 17.0N 108.5W Thu afternoon, 17.9N 108.9W Fri morning, 18.9N 109.4W Fri afternoon, and 20.0N 109.8W Sat morning. Norma will change little in intensity as it moves to near 22.1N 110.1W early Sun. Elsewhere, winds over the Gulf of Tehuantepec will diminish below gale- force by early this afternoon. Fresh to strong winds will continue to pulse over the Tehuantepec region through the remainder of the week. Seas in the Tehuantepec region will subside through the day as winds diminish. Gentle to moderate winds will prevail elsewhere through the end of the week. Fresh to strong winds offshore Baja California may develop this weekend. Large NW swell is forecast to spread offshore Baja California by the end of the week into the weekend. Looking ahead, an area of low pressure is forecast to form south of the coasts of Guatemala and eastern Mexico in a couple of days. Gradual development of this system is expected, and a tropical depression is likely to form late this week or over the weekend while the system meanders over the far eastern portion of the basin. This system has a low chance of tropical cyclone development in the next 48 hours, and high chance through 7 days. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate to fresh gap winds are over the Papagayo region, with moderate winds extending downstream of Papagayo. Light to gentle winds are noted elsewhere N of the monsoon trough. Gentle winds are S of the monsoon trough. Seas are in the 6-8 ft range well offshore Guatemala, 4-6 ft over and downstream of the Gulf of Papagayo, and 3-5 ft elsewhere across the discussion waters. For the forecast, moderate to rough seas from swell generated by the Gulf of Tehuantepec gale-force gap wind event will subside well offshore of Guatemala through the day. Winds will pulse moderate to fresh, locally strong, near the Gulf of Papagayo at night through Thu night. Gentle to moderate winds will prevail south of the monsoon trough. Seas may build slightly in SW swell offshore Ecuador to the Galapagos Islands by the end of the week into the weekend. Looking ahead, an area of low pressure is forecast to form south of the coasts of Guatemala and eastern Mexico in a couple of days. Gradual development of this system is expected, and a tropical depression is likely to form late this week or over the weekend while the system meanders over the far eastern portion of the basin. This system has a low chance of tropical cyclone development in the next 48 hours, and high chance through 7 days. ...REMAINDER OF THE AREA... Please see the SPECIAL FEATURES section above for more details on Tropical Storm Norma, and for details on a large NW swell event over the NW waters. A 1022 mb high pressure center near 35N131W extends a ridge to near the Revillagigedo Islands. Light winds are over the fare NW waters. Gentle to moderate winds are elsewhere over the discussion waters. NW swell is propagating across the NW waters bringing seas of 8-12 ft N of 10N and W of 135W, with a separate area of N to NW swell propagating across the waters N of 28N between 118W and 125W. Elsewhere, seas of 5-7 ft prevail. For the forecast, the large set of NW swell over the NW waters will peak near 13-15 ft today and tonight. Seas greater than 8 ft associated to this swell will merge with seas generated by Norma to cover much of the discussion waters W of 100W by the end of the week. Meanwhile, southerly swell of 8 ft or greater will spread N of the Equator through the end of the week. Seas will gradually subside from west to east over the waters W of 125W Fri night through the weekend. $$ AL