000 AXPZ20 KNHC 040756 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sat Nov 4 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 0900 UTC. ...SPECIAL FEATURES... Tropical Storm Pilar is centered near 9.8N 107.3W at 04/0900 UTC, moving west at 14 kt. Estimated minimum central pressure is 1002 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Scattered strong convection is evident within 210 nm in the northwest semicircle from the center, and within 60 nm in the southeast semicircle. Peak seas are currently around 16 ft. Pilar will continue moving toward the west during the next couple of days. By early next week, a slower west- northwestward motion is forecast. Little change in strength is forecast during the next few days. 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 Pilar NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Gulf of Tehuantepec Gale Warning: Strong north winds persist at Salina Cruz, on Pacific coast of the isthmus of Tehuantepec in southern Mexico. Along with data from a 02 UTC scatterometer satellite pass, this suggests gale-force gap winds persist across the adjacent Gulf of Tehuantepec. The gales are due to cooler, drier air and high pressure over the Gulf of Mexico, and lower pressure farther south into the tropical Pacific. Seas are likely reaching 15 ft downstream in the Gulf of Tehuantepec, with a large plume of rough seas in excess of 8 ft extending beyond 500 nm offshore. Gap winds will diminish below gale force Sun night, but strong gap winds and rough seas will persist until late Tue. Please read the latest NHC High Seas forecast at www.hurricanes.gov/marine for more details. Potential for heavy rainfall over Central America: A disturbance (Invest 97L) is moving into northern Central America. Plenty of tropical moisture and an unstable atmosphere are forecast to produce heavy rains through the weekend across Central America. This rainfall may result in flash flooding and landslides. Please refer to the local weather services for more information. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 12N87W to 08N101W. The ITCZ extends from 07N110W to 09N125W to beyond 08N140W. Scattered moderate convection is noted from 08N to 11N east of 88W, and from 06N to 09N west of 135W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please refer to the Special Features section above for details on the Gulf of Tehuantepec Gale Warning. Outside of the Gulf of Tehuantepec gap wind event, surface ridging extends across the Baja California offshore waters anchored by a 1023 mb high pres near 31N130W. The pressure gradient from this high pressure and lower pressure over Mexico is leading to moderate to fresh NW to N winds in the Gulf of California, with 2 to 4 ft seas. Meanwhile, light to gentle winds are noted across the rest of the Mexico offshore waters. Seas range 4 to 6 ft in mixed swell. For the forecast, Gale force gap winds will persist across the Gulf of Tehuantepec into Sun night, related to high pressure north of the area following a cold front that entered southern Mexico a couple of days ago. Very rough seas associated with the gales will continue over the waters off eastern Oaxaca and western Chiapas into Mon morning. The winds and seas will continue to gradually diminish into Tue off southern Mexico. Looking ahead, expect fresh NW winds and large NW swell off Baja California north of Cabo San Lazaro as high pressure builds west of the area behind a cold front that moves into the region and stalls. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate S-SW monsoonal winds prevail across the offshore waters with seas 4 to 6 ft. Seas range 8 to 9 ft across the offshore waters of Guatemala due to the Tehuantepec gap wind event, west of 93W. Mixed swell will persist across the Central American and South American offshore waters. Scattered showers and thunderstorms are across the waters from Costa Rica southeastward to southern Colombia as described above. For the forecast, expect large seas off Guatemala through Sun night due to swell generated off southern Mexico from gale force winds in the Gulf of Tehuantepec. Gentle to moderate winds and slight to moderate seas will persist elsewhere. ...REMAINDER OF THE AREA... Please refer to the Special Features section above for details on Tropical Storm Pilar. A few showers may be ongoing near a trough near 125W from 12N to 25N. The trough had previously been a well developed low pressure area, but has since weakened. Winds have subsequently diminished as well, but an altimeter satellite pass from a few hours ago indicated combined seas up to 7 ft were lingering near the trough. Surface ridging extends across the region elsewhere north of 20N anchored by a 1021 mb high pressure near 29N135W, supporting mostly moderate trade winds mainly from 10N to 20N. Earlier scatterometer and recent altimeter satellite passes indicated fresh trade winds with combined seas close to 9 ft from 08N to 15N west of 135W. For the forecast, Pilar will move to 9.8N 109.4W this afternoon, 10.1N 111.7W Sun morning, 10.6N 113.6W Sun afternoon, 11.3N 115.3W Mon morning, 11.9N 116.4W Mon afternoon, and weaken to a remnant low near 12.7N 117.5W Tue morning. Pilar will change little in intensity as it moves to near 14N 120W by early Wed. Otherwise, mainly moderate to fresh winds will prevail north of the ITCZ and monsoon trough through early next week. Seas will be mainly 5-7 ft through late Mon, with seas to 8 ft across the trade wind zone. Looking ahead, a weak cold front is expected to push across the waters north of 25N through Mon, accompanied by seas 8 to 9 ft which will cover most of the area north of 10N and west of 120W by mid week. $$ Christensen