000 AXPZ20 KNHC 182108 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 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 1800 UTC surface analysis and satellite imagery through 1800 UTC. ...SPECIAL FEATURES... Newly upgraded Hurricane Norma is centered near 15.6N 108.0W at 18/2100 UTC, moving north at 7 kt. Estimated minimum central pressure is 984 mb. Maximum sustained wind speed is 70 kt with gusts to 85 kt. Peak seas are currently around 22 ft. Numerous moderate scattered strong convection is noted within 600 nm in the E semicircle, and 210 nm in the W semicircle. Norma is moving toward the north, and a northward to north-northwestward motion at a similar forward speed is expected during the next few days. Continued rapid strengthening is forecast through tonight, and Norma could become a major hurricane on Thursday. Gradual weakening is forecast on Friday and Saturday. Swells generated by Norma are affecting portions of the coast of southwestern Mexico, and will spread northward along the coast of western Mexico and toward Baja California Sur during the next couple of days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office. Interests in Baja California Sur should monitor the progress of Norma. 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 Norma NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. NW Swell in the NW waters: Large NW swell has propagated into the NW waters. Seas of 12 ft or greater have reached roughly N of 25N and W of 135W per recent altimeter data, which also indicates they are peaking around 15 ft. Seas of around 12 ft or greater will continue to spread SE to near N of 20N and W of 130W through early Thu, while the edge of seas of 8 ft or greater manages to cover the majority of the waters W of 100W by the end of the week. By that time, peak seas should subside to just below 12 ft. Confused and hazardous seas will be the result of the combination of the NW swell, SW swell moving N of the Equator, and swells generated by Norma by the end of the week. Seas will 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 09.5N80W to low pressure near 08N95W to 11N100W, then resumes SW of Norma near 10N113W to low pressure near 11N121W to 08N140W. Scattered moderate isolated strong convection is noted from 06N to 11N between 99W and 100W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the SPECIAL FEATURES section above for more details on newly upgraded Hurricane Norma. Gale force winds have recently diminished in the Gulf of Tehuantepec, now at fresh to near gale force. Seas are likely 8-10 ft there. Aside from newly upgraded Hurricane Norma, 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. Seas are in the 6-8 ft range offshore Baja California Norte, and 4-7 ft elsewhere over the open waters off Mexico. Seas of 1-2 ft are noted over the Gulf of California. For the forecast, Norma will move to 16.6N 108.1W Thu morning, 17.7N 108.3W Thu afternoon, 18.7N 108.7W Fri morning, 19.6N 109.1W Fri afternoon, 20.8N 109.7W Sat morning, and 22.1N 110.0W Sat afternoon. Norma will change little in intensity as it moves to 22.7N 109.9W Sun afternoon. Elsewhere, fresh to strong N winds will continue to pulse over the Tehuantepec region through the remainder of the week. 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, resulting in confused and hazardous seas as it mixes with swells generated by Norma. A new set of NW swell may spread offshore Baja California early next week. Meanwhile, a broad area of low pressure located several hundred nautical miles south of the Gulf of Tehuantepec is producing some disorganized showers and thunderstorms. Gradual development of this system is expected, and a tropical depression is likely to form over the weekend while the system meanders or drifts northwestward over the far eastern portion of the basin. This system has a low chance of tropical cyclone formation through 48 hours, and a 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, extending downstream of Papagayo to near 10N94W. Light to gentle winds are noted elsewhere N of the monsoon trough. Gentle to moderate winds are S of the monsoon trough. Seas are in the 5-8 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. Scattered showers and isolated thunderstorms are found offshore Colombia. For the forecast, moderate seas from swell generated by a Gulf of Tehuantepec gap wind event will subside offshore Guatemala tonight. Winds will pulse moderate to fresh near the Gulf of Papagayo through Thu morning. 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, then build slightly across the waters from W to E by the end of the weekend as NW swell arrives. Meanwhile, a broad area of low pressure located several hundred nautical miles south of the Gulf of Tehuantepec is producing some disorganized showers and thunderstorms. Gradual development of this system is expected, and a tropical depression is likely to form over the weekend while the system meanders or drifts northwestward over the far eastern portion of the basin. This system has a low chance of tropical cyclone formation through 48 hours, and a high chance through 7 days. ...REMAINDER OF THE AREA... Please see the SPECIAL FEATURES section above for more details on newly upgraded Hurricane Norma, and for details on a large NW swell event over the NW waters. Ridging dominates the waters N of the monsoon trough. Light winds are over the far NW waters. Gentle to moderate winds are elsewhere over the discussion waters. Other than the NW swell described above, seas of 5-7 ft prevail, reaching to around 8 ft S of the Equator to 03.4S to the W of 110W. For the forecast, other than the large NW swell event, Norma will move to 16.6N 108.1W Thu morning, 17.7N 108.3W Thu afternoon, 18.7N 108.7W Fri morning, 19.6N 109.1W Fri afternoon, 20.8N 109.7W Sat morning, and 22.1N 110.0W Sat afternoon. Norma will change little in intensity as it moves to 22.7N 109.9W Sun afternoon. Mainly gentle to moderate winds under a weak pressure pattern will prevail elsewhere across the open waters through the weekend. Winds may increase somewhat early next week as the pressure gradient tightens. Meanwhile, a new set of NW swell, fresh swell, generated offshore California, is forecast to spread S of 30N to the E of 130W by early next week potentially building seas to 7-11 ft N of 25N. $$ Lewitsky