000 AXPZ20 KNHC 090843 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Wed Dec 9 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 0600 UTC surface analysis and satellite imagery through 0840 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 around 14-15 ft. Winds are forecast to diminish below gale force tonight. Swell generated from these gales will spread well away from the Tehuantepec region, with seas 8 ft or greater reaching as far west as 110W today. 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 09N84W to 06N97W to 08N125W. The ITCZ continues from 08N125W to beyond 08N140W. Scattered moderate convection is noted from 06N to 10N between 104W and 113W, and from 08N to 11N west of 135W. 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 waters off Baja California, with seas currently reaching 13 ft off Baja California Norte. Seas greater than 8 ft will prevail through the week, then subside below 8 ft Sat. Light to gentle winds prevail across the regional waters north of 21N, produced by the weak pressure gradient related to deep layered low pressure and associated 1013 surface low near 29N120W. This surface low is expected to drift E 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. Elsewhere, over the waters off SW Mexico, seas are in the 4-6 ft range. Seas there will build to 7-9 ft today through Thursday in a mix of large NW swell, and NE swell generated by the Gulf of Tehuantepec gale force gap wind event. High pressure will build across the Baja offshore waters Thu and Thu night to bring a return to moderate northerly winds off Baja California Thu night through Sat. 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 through 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 today. 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 1013 mb surface low centered near 29N120W. The pressure gradient between the area of high pressure and this low is supporting moderate to fresh winds west of the low. The low will drift E and gradually weaken through early Thu. Long period NW swell is propagating over the NW portion of the forecast region, and will continue to spread SE across the forecast waters. Seas 8 ft or greater cover the waters NW of 21N110W to 02N140W. Seas greater than 12 ft cover much of the waters north of 22N between 116W and 135W. Seas greater than 8 ft with this swell will cover much of the waters west of 105W by tonight. Seas will slowly subside, and fall below 8 ft over much of this area by Sat. $$ AL