656 AXPZ20 KNHC 292211 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Thu Oct 29 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning...Strong high pressure is building across NE Mexico and the western Gulf of Mexico behind a cold front that has reached the central Bay of Campeche this afternoon. The front will move southeastward and reach the eastern Bay of Campeche tonight through Fri and allow strong northerly gap winds to funnel through the Chivela pass and across the Gulf of Tehuantepec. Computer model guidance shows a rapid increase in northerly winds to near gale force late this afternoon through evening, increasing to 40 kt tonight, with gales continuing into Sat morning. Strong gap winds will persist Saturday, with gales returning Sun morning as a reinforcing front moves across the Gulf of Mexico. Peak seas during this gale wind event are expected to build to around 16 ft Fri afternoon and then to near 20 ft Mon evening. ...TROPICAL WAVES... A tropical wave axis is along 83W/84W, along the east coast of Nicaragua, extending southward across Costa Rica to 05N, moving westward at 15-20 kt. Associated convection is described below and extends northward across the Caribbean between 78W and the Caribbean coasts of Nicaragua and NE Honduras. This wave is expected move westward across Central America and the waters E of 90W in the next 48 hours. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 11N75W to low pres 1009 mb near 11N81W to low pres 1007 mb near 10N88W to 12N112W to 09.5N134W to beyond 10N140W. Scattered moderate to strong convection is noted from 06N to 11N between 79W and 91W, from 09N to 12.5N between 93W and 99W, from 09.5N to 16N between 103W and 123W, and from 07N to 10N between 132W and 141W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Light to gentle NW to N winds prevail across the offshore waters of Baja California this afternoon, where seas are 4 to 6 ft, except to 7 ft well offshore of Cabo San Lucas. These relatively tranquil conditions are expected to persist through the weekend. Late morning ASCAT data showed gentle to moderate northerly winds persisting across north and central portions of the Gulf of California, where peak seas are likely 3-4 ft. These conditions are generally expected to continue through late Friday before diminishing modestly through the weekend. Winds will remain light to gentle over the SW Mexico offshore waters south of 19N, except for the offshore waters between Puerto Vallarta and Manzanillo out to 110W, where moderate N to NE winds are expected through this evening. Except for offshore the Gulf of Tehuantepec, gentle to moderate winds are expected elsewhere through the weekend. Winds and seas will increase rapidly offshore and downwind of Tehuantepec this evening through the weekend as a significant gale gap wind event dominates the region. See above for details. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Moderate south to southwest winds will prevail south of the monsoon trough through Sun, with isolated areas of fresh winds this afternoon through tonight ahead of an approaching tropical wave. Seas are expected to increase offshore of Guatemala and El Salvador Fri through Sat night due to gale force winds in the Gulf of Tehuantepec pushing northerly waves into the area. Moderate offshore gap winds are expected across the Papagayo region Fri through Sun before turning onshore Mon. Active weather is expected across the waters north of 05N, from the Papagayo region southeast into Central America and the Gulf of Panama this afternoon and tonight. Ample moisture persists across the region, and the tropical wave along 83W/84W will act as a focus for deep convection. Showers and thunderstorms will gradually shift west along with the wave tonight through Fri, and move well offshore by late Fri. REMAINDER OF THE AREA... A broad ridge persists across the northern forecast waters west of 120W. The gradient between the ridge and lower pressures associated with the monsoon trough will support moderate to fresh NE trade winds over an area roughly from 10N to 22N, west of 115W, for the next several days. Seas are 6 to 8 ft across this region, in a mix of swell and easterly wind waves. Little change is expected through Fri. South of the monsoon trough, moderate to fresh S to SW winds prevail between 100W and 130W, where seas are 7-9 ft. Minor fluctuations in winds and seas are expected across this area through the weekend. Looking ahead, computer models suggest that a tropical wave moving offshore of SW Mexico Sun and Mon could spawn a low pressure center forming west of the offshore waters in the vicinity of 11N108W by Mon morning, and move WNW through mid week. Environmental conditions appear favorable for gradual organization of this system next week. $$ Stripling