000 AXPZ20 KNHC 100240 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Thu Dec 10 2020 Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 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 0240 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: The pressure gradient between high pressure over the Gulf of Mexico and the eastern north Pacific monsoon trough continues to support minimal gale force northerly winds across the Gulf of Tehuantepec, with peak seas to 13 ft. Winds are forecast to diminish below gale force late tonight as the high pressure weakens. Swell generated from these gales has spread well away from the Tehuantepec region, with seas 8 ft or greater reaching as far west as 115W in a mix of NE swell from the gap winds and longer period NW swell. Please read the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.html for more details. Of note: Based on the last 20 years, 329 gale and 106 storm- force gap wind events have been observed in the Tehuantepec region, an average of 16 gale and 5 storm events per cold season. The average starting date for Tehuantepec gale events is around October 25th, and the average date of the last event is around April 9th. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N81W to 06.5N92W to 1012 mb low pressure near 09N112W to 09N115W. The ITCZ continues from 09N115W to beyond 09N140W. Scattered moderate convection is noted from 06N to 09N between 86W and 101W, from 07N to 10N between 107W and 115W, and from 08N to 10N between 125W and 140W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for more on the Gulf of Tehuantepec gale force gap wind. NW swell prevails across the open waters off Mexico. Seas greater than 8 ft prevail over much of these waters, with seas peaking near 11 ft off Baja California. The swell will slowly subside, and fall below 8 ft over much of these waters Sat. A new round of NW swell with wave heights in excess of 8 ft will reach the waters off Baja California Norte this weekend. These seas will push southward but subside to below 8 ft through early next week. A deep layer low pressure area is centered off Baja California Norte, supporting a 1014 mb surface low near Guadalupe Island. The surface low is expected to drift eastward and weaken through early Thu. As the low moves across the waters of Baja Norte expect gentle to moderate W to SW winds before the low moves inland late tonight and weakens to a trough early Thu. High pressure will build in the wake of the low and trough, supporting fresh northerly winds across the Gulf of California late Sat through late Sun. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to strong offshore gap winds will prevail through early Fri as high pressure prevails over the western Caribbean. Winds may reach near gale-force tonight. Seas will build to near 10-11 ft on Thu, with seas greater than 8 ft extending well downwind of the Papagayo region by the end of the week. Elsewhwere, gentle to moderate S to SW winds will prevail south of the monsoon trough through the next several days. Swell generated in the Tehuantepec region will continue to propagate over the waters off Guatemala and El Salvador, producing seas of up to 9 ft tonight. Seas in the 4-6 ft range will prevail elsewhere. REMAINDER OF THE AREA... The pressure gradient between high pressure north of the area and lower pressure in the vicinity of the ITCZ, and within the monsoon trough, is supporting an area of moderate to fresh trade winds roughly from 08N to 20N west of 125W. Deep layered low pressure is supporting a 1014 mb surface low centered near 29N119W. The pressure gradient between the area of high pressure and this low is supporting moderate winds west of the low. The low will drift E and gradually weaken through early Thu. Long period NW swell is propagating over the forecast region. Seas 8 ft or greater cover the waters west of 100W. Seas will slowly subside, and fall below 8 ft over much of the area east of 115W by Sat. Looking ahead, a new round of northerly swell of 8 to 10 ft will push south into the waters north of 25N early next week. $$ AL