000 AXPZ20 KNHC 190345 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Oct 19 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 0350 UTC. ...TROPICAL WAVES... A tropical wave is along 83W north of 03N through southern Costa Rica, moving west at 10 to 15 kt. Scattered moderate convection is N of 04N between 81W and 88W. A tropical wave extends along 91W north of 02N to Guatemala, moving westward at 10-15 kt. Numerous moderate to strong convection is N of 13N between 89W and 92W. Scattered moderate convection is elsewhere from 05N to 13N between 88W and 95W. A tropical wave extends along 107W from 03N to 15N, moving westward at 10-15 kt. No significant convection is noted with this wave. A tropical wave extends along 126W from 03N to 15N, moving westward at 15 kt. Scattered moderate convection is from 05N to 13N between 116W and 133W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 07N78W to 11N100W to 1010 mb low pressure near 11N111W, to 09N125W to 13N135W. The ITCZ continues from 13N135W to beyond 13N140W. Aside from the convection associated with the tropical waves discussed in the section above, scattered moderate convection is observed from 07N to 12N between 95W and 100W, and from 08N to 10N between 107W an 114W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See the Special Features section above for more information on the ongoing Gale Warning for the Gulf of Tehuantepec. A recent scatterometer satellite pass indicated strong to near- gale force gap winds through the Gulf of Tehuantepec, with a plume of winds in excess of 20 kt reaching as far as 300 nm downstream into the Pacific. An earlier radar altimeter satellite pass showed seas near 11 ft just outside the main plume of winds. Winds and seas are subsiding as high pressure over the western Gulf of Mexico weakens and shifts eastward. Farther north, a weak cold front is approaching Baja California Norte. Moderate to fresh westerly gap winds are active over the northern Gulf of California ahead of the front. Elsewhere, a weak pressure pattern is maintain gentle to moderate mainly NW winds over Mexican offshore waters, with 3 to 5 ft seas primarily in SW swell. For the forecast, the strong gap winds through Tehuantepec will continue to diminish through mid week. However, a broad area of low pressure is expected to form in a few days a couple of hundred miles south of the coast of southern Mexico. Environmental conditions are expected to be conducive to support some development thereafter, and a tropical depression could form late this week or this weekend while the system moves west- northwestward to northwestward near or just south of the coast of southern Mexico. Farther north, the approaching cold front will stall and dissipate off Baja California through Tue, but will be accompanied by NW swell allow seas north of Cabo San Lazaro through mid week. Another larger set of NW swell will start to move into the waters near Guadalupe Island by Thu, bringing seas in excess of 8 ft to all the offshore waters of Baja California Fri and Sat. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... The monsoon trough extends east to west along roughly 10N through mid week then lift north of the region. A few showers and thunderstorms are active along the monsoon trough from western Panama to El Salvador. Light to gentle easterly winds persist north of the monsoon trough, with moderate southwest to west winds south of the monsoon trough. Seas are 4 to 6 ft in SW swell. For the forecast, a broad area of low pressure is expected to form in a few days a couple of hundred miles south of the coast of southern Mexico. Some slow development of this system is possible thereafter as it moves WNW off the coast of Mexico. As this occurs, the monsoon trough will move northward, allowing SW to W winds across the region. Looking ahead, seas will build off Ecuador and Colombia in increased southerly swell. REMAINDER OF THE AREA... Moderate to locally fresh NE winds continue over the waters N of the monsoon trough and west of 120W, with gentle to moderate winds south of the monsoon trough. Gentle to moderate N to NE winds and seas in the 5-7 ft range will change little into Tue. A NW swell expected to raise seas to 8 ft will move into the waters N of 27N between 120W-130W Tue into Wed, then subside. Looking ahead, another round of NW swell will accompany a cold front that will move into the waters N of 28N and W of 130W Tue night, with seas in excess of 8 ft dominating the waters NW of a line from Guadalupe Island to 14N140W by late Thu. Reinforcing NW swell will follow over the same area through Sat. $$ Ramos