000 AXPZ20 KNHC 201618 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Fri Oct 20 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 1200 UTC surface analysis and satellite imagery through 1530 UTC. ...SPECIAL FEATURES... Hurricane Norma is centered near 19.4N 109.2W at 20/1500 UTC, moving NNW at 7 kt. Estimated minimum central pressure is 960 mb. Maximum sustained wind speed is 95 kt with gusts to 115 kt. Norma is a category 2 hurricane on the Saffir-Simpson Hurricane Wind Scale. Peak seas are around 36 ft with the 12 ft seas extending within 270 nm of the center except 210 nm in the NE quadrant. Numerous moderate to strong convection is noted from 17N to 22N between 107W and 112W. A NNW to N motion is forecast through Saturday, followed by a turn toward the northeast on Sunday. On the forecast track, Norma is expected to approach the southern portion of Baja California Sur tonight and move near or over the area on Saturday. Norma is forecast to move toward the west coast of mainland Mexico on Sunday and Sunday night. Gradual weakening is expected during the next few days, but Norma is forecast to be a hurricane when it moves near or over the southern portion of Baja California Sur. Swells generated by Norma are affecting portions of the coast of southwestern and west-central Mexico and Baja California Sur. These swells will spread northward along the coast of western Mexico and the Baja California peninsula this weekend. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office and 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. South of Southern Mexico (EP91): A broad area of low pressure located several hundred miles south of the Gulf of Tehuantepec continues to produce large area of showers and thunderstorms, mainly over the western part of the circulation. This scattered moderate to isolated strong convection is noted from 06N to 1N between 96W and 99W. Upper- level winds are forecast to become more conducive for development later this weekend, and a tropical depression will likely form by early next week. The system is forecast to meander during the next couple of days and then drift generally northward late this weekend and into early next week. This system has a medium chance of tropical cyclone formation through 48 hours, and a high chance through 7 days. Please read the latest NHC Tropical Weather Outlook at www.hurricanes.gov for details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from the coast of Costa Rica near 10N86W to low pressure (EP91) near 09N96W 1007 mb to 23N101W, then resumes near 13N112W to low pres near 20N121W 1008 mb to 07N130W to 11N140W. Scattered moderate isolated strong noted from 02N to 10N between 78W and 93W. Scattered moderate convection is noted from 06N to 13N between 110W and 124W and from 07N to 12N and W of 133W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the SPECIAL FEATURES section above for more details on Hurricane Norma and low pressure (EP91) near 08N95W. Aside from Hurricane Norma, a ridge extends W of the Baja California offshore waters. Moderate NW winds prevail across most of the Baja California offshore waters. NW swell continues to move across this area bringing seas 8 to 10 ft. In the Gulf of Tehuantepec, fresh to strong winds prevail with seas to 8 ft. Elsewhere, light to gentle winds are noted in the Gulf of California. Seas are mostly to 4 ft across the Gulf except 5 to 7 ft in the entrance of the Gulf due to the influence of Norma. Across the southern Mexico offshore waters, light to gentle winds prevail with seas 6 to 10 ft due to swell from Norma. For the forecast, Norma will move to 20.6N 109.6W this evening, 22.1N 109.8W Sat morning, 23.3N 109.6W Sat evening, weaken to a tropical storm near 23.9N 109.1W Sun morning, 24.3N 108.3W Sun evening, and inland to 24.7N 107.4W Mon morning. Norma will weaken to a tropical depression while moving inland near 26.0N 106.0W by early Tue. Elsewhere, fresh to strong N winds will continue to pulse over the Tehuantepec region through Sat morning. Fresh to locally strong winds can be expected across the Baja California offshore waters this weekend. Large NW swell is forecast to continue to spread offshore Baja California into the weekend, resulting in confused and hazardous seas as it mixes with swells generated by Norma. Most of the swell will subside by Mon morning. A new set of NW swell may spread offshore Baja California early next week. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see the SPECIAL FEATURES section above for more details on low pressure (EP91) near 08N95W. Moderate to locally fresh winds are noted in the offshore waters of Guatemala and El Salvador due to the influence of EP91. Otherwise, gentle to moderate winds prevail N of the monsoon trough in the Central American offshore waters. Seas range 5 to 8 ft with the higher seas close to EP91. South of the monsoon trough, gentle to moderate W to SW winds are noted with seas 5 to 7 ft within S to SW swell. Strong thunderstorms with heavy rainfall continues across offshore Colombia, Panama, and Costa Rica. For the forecast, other than the low pressure area (EP91), light to gentle winds will prevail north of the monsoon trough in the Papagayo region through early next week. 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 weekend, spreading across the rest of the offshore waters from W to E by early next week as NW swell arrives. ...REMAINDER OF THE AREA... Please see the SPECIAL FEATURES section above for more details on Hurricane Norm and low pressure (EP91) near 08N95W. Surface ridging extends across the northern forecast waters, N of 17N and W of 119W anchored by a 1015 mb high pres near 25N135W. Moderate SW winds are noted in the NW corner of the area ahead of a dying stationary front, N of 27N and W of 137W. Light to gentle winds prevail elsewhere across this area N of the monsoon trough. S of the monsoon trough, gentle to moderate S to SW winds are noted. Large NW swell continues to propagate across most of the waters. Peak seas are around 12 ft according to altimeter data. Seas of 8 ft or greater covers the majority of the waters W of 100W today. Confused and hazardous seas will result from the combination of the NW swell, SW swell moving N of the Equator, and swells generated by Norma through the end of the week and into the weekend. Seas will gradually decay from west to east tonight through the upcoming weekend. Please read the latest NHC High Seas Forecast at website www.hurricanes.gov/marine for more details. For the forecast, other than the large NW swell event and low pressure (EP91), Norma will move to 20.6N 109.6W this evening, 22.1N 109.8W Sat morning, 23.3N 109.6W Sat evening, weaken to a tropical storm near 23.9N 109.1W Sun morning, 24.3N 108.3W Sun evening, and inland to 24.7N 107.4W Mon morning. Norma will weaken to a tropical depression while moving inland near 26.0N 106.0W by early Tue. Elsewhere, a weak pressure pattern will support mainly gentle to moderate winds across the open waters through the weekend. Winds may increase moderate to locally fresh by early next week as high pressure builds N of the area and tightens the pressure gradient. Meanwhile, a new set of NW swell is forecast to spread S of 30N to the E of 130W by early next week, potentially building seas to 7-10 ft N of 24N. $$ AReinhart