000 AXPZ20 KNHC 180252 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 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 0000 UTC surface analysis and satellite imagery through 0230 UTC. ...SPECIAL FEATURES... Tropical Storm Norma is centered near 13.7N 107.8W at 18/0300 UTC, moving northwest at 7 kt. Estimated minimum central pressure is 1000 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Peak seas are currently around 14 ft. Numerous moderate isolated strong convection is noted from 10N to 20N between 98W and 112W. Scattered moderate and isolated strong convection is noted from 03N to 10N between 100W and 112W. Norma is moving toward the northwest, and a slow northwestward to north-northwestward 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 could become a hurricane on Wednesday. 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 pressure gradient between high pressure along the eastern slopes of Mexico and the eastern north Pacific monsoon trough is supporting gale-force gap winds, up to 40 kt. Peak seas are likely reaching near 14-15 ft with these winds. The area of high pressure will shift eastward tonight. This will loosen the pressure gradient which will help diminish winds below gale-force by early Wed 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 will push SE of 30N140W tonight building seas to 12 ft or greater N of 25N and W of 135W by early Wed afternoon. Seas will peak around 15 ft Wed 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 10N86W to 11N102W. It resumes SW of Norma near 12N110W to 08N140W. Scattered moderate and isolated strong convection is noted from 03N to 14N E of 98W, and from 03N to 10N between 112W and 128W. ...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 5-8 ft range offshore Baja California Norte, and 4-6 ft elsewhere over the open waters off Mexico. Seas of 1-3 ft are noted over the Gulf of California. For the forecast, Norma will move to 13.8N 108.0W Wed morning, 15.0N 108.4W Wed afternoon, strengthen to a hurricane near 16.0N 108.6W Thu morning, 16.9N 108.8W Thu afternoon, 17.8N 109.1W Fri morning, and 18.7N 109.6W Fri afternoon. Norma will change little in intensity as it moves to 20.9N 110.3W Sat afternoon. Elsewhere, gale-force gap winds will prevail over the Gulf of Tehuantepec through Wed morning. Fresh to strong winds will continue to pulse over the Tehuantepec region through the remainder of the week. Rough to very rough seas can be expected over this area through Wed. 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... Gentle to moderate gap winds are over and downstream the Papagayo region. Light to gentle winds are noted elsewhere N of the monsoon trough. Gentle winds are S of the monsoon trough. Seas are in the 6-9 ft range well offshore Guatemala, and in the 3-5 ft range 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 prevail well offshore of Guatemala until early Wed. 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 1019 mb high pressure center near 29N132W extends a ridge to near the Revillagigedo Islands. Light winds are in the vicinity of the high center. Gentle to moderate winds are elsewhere over the discussion waters. NW swell is propagating across the NW waters bringing seas of 7-9 ft N of 10N and W of 135W, with a separate area of fresh NW swell propagating across the waters N of 28N between 118W and 124W. Elsewhere, seas of 5-7 ft prevail. For the forecast, a large set of NW swell is expected to move into the NW waters late tonight, with seas peaking near 13-15 ft on Wed and Wed night. 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 mid-week 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