035 AXPZ20 KNHC 220403 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed Sep 22 2021 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 0000 UTC surface analysis and satellite imagery through 0340 UTC. ...SPECIAL FEATURES... A Gale Warning is in effect for the Gulf of Tehuantepec Wed night into Thu. An early season cold front is expected to enter the NW Gulf of Mexico early Wed and reach from the NE Gulf to central Bay of Campeche by late Thu. High pressure building in the wake of the front across the eastern slopes of the Sierra Madre Mountains and the western Gulf of Mexico will support this gap wind event forecast to reach minimal gale force Wed night into Thu. Seas are forecast to build to 9-11 ft with this event. Please, refer to the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...TROPICAL WAVES... The axis of a tropical wave is along 108W and from 07N to 18N, moving west at 10 to 15 kt. Scattered moderate convection is noted from 08N to 14N between 107W and 114W. The axis of a tropical wave is along 121W from 08N to 19N, moving west at 10 to 15 kt. A 1010 low pressure is along the wave axis near 13N121W. Scattered moderate convection is from 12N to 19N between 114W and 125W. The axis of a tropical wave is along 137W from 04N to 16N, moving west at 10 to 15 kt. A 1011 low pressure is along the wave axis near 09N137W. Scattered moderate convection is seen from 06N to 10N W of 134W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N85W to 12N110W to 1010 mb low pressure located near 13N121W to 13N126W. The ITCZ begins near 09N123W to beyond 07N140W. Aside from the convection associated with the tropical waves, scattered moderate convection is from 05N to 13N between E of 104W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Surface ridging over the N Pacific open waters extends to the offshore waters of Baja California Norte and continue to provide gentle to locally moderate NW winds with seas to 5 ft in NW swell. Latest scatterometer data show light to gentle NW winds in the Gulf of California and gentle to moderate winds along the coast of Jalisco and Michoacan. Altimeter data indicate seas in the 4 to 5 ft range in that region, except for 1 to 3 ft in the gulf of California. Otherwise, fresh to strong winds are already occurring in the Gulf of Tehuantepec with seas to 6 ft. Winds will further increase in this region Wed and Wed night. Please, see the Special Features section for more details. For the forecast, a ridge will continue to dominate the offshore waters of Baja California supporting gentle to moderate NW winds through the next several days. In the Gulf of California, abundant moisture will persist across the central and southern parts of the Gulf tonight and Wed, with winds veering to the NW and N. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gentle to moderate southerly winds will prevail across the offshore waters of Costa Rica, Panama, Colombia and Ecuador during the forecast period, with seas of 4-6 ft in SW swell. Mainly light and variable winds are forecast across the offshore waters from Guatemala to northern Costa Rica, with seas of 3-5 ft also in SW swell. Long period SW swell will reach the waters between Ecuador and the Galapagos Islands during the upcoming weekend, building seas to 7 or 8 ft. REMAINDER OF THE AREA... A broad area of low pressure located over 800 miles southwest of the southern tip of the Baja California peninsula continues to produce some disorganized shower activity. Environmental conditions are somewhat conducive for development, and a short-lived tropical depression could form by late this week while the low moves generally northwestward. This system is forecast to move over cooler waters and into a more stable environment by the weekend, which should inhibit further development. The latest Tropical Weather Outlook gives this system a low chance of tropical cyclone formation through 48 hours, and a medium change through 5 days. Please, refer to the latest Tropical Weather Outlook, at www.hurricanes.gov for more details. The northern forecast waters remain under the influence of a surface ridge. The pressure gradient between the ridge and lower pressures near the monsoon trough/ITCZ supports moderate to locally fresh trades roughly from 10N-20N W of 120W, with seas of 5-7 ft based altimeter data. $$ Ramos