000 AXPZ20 KNHC 170918 CCA TWDEP Tropical Weather Discussion...Corrected NWS National Hurricane Center Miami FL 0405 UTC Sun Oct 17 2021 Corrected ITCZ/Monsoon Trough section 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 0345 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: High pressure is building across the Gulf of Mexico as a cold front pushes across the basin. The associated tight gradient has initiated gale force gap winds over the Gulf of Tehuantepec. These winds will continue through early Mon. Seas are expected to build to 9 to 13 ft downwind of the gale force winds by early Sun evening, then slowly subside Mon. Please see the latest High Seas Forecast at http://nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...TROPICAL WAVES... A tropical wave has its axis along 85W north of 02N to inland central Nicaragua and eastern Honduras. It is moving westward at 10-15 kt. Scattered moderate to isolated strong convection is within 120 nm east of the axis from 07N to 09N. A tropical wave has its axis along 97W from 02N to 16N, moving westward at 10-15 kt. Isolated showers and thunderstorms are noted within 180 nm west of the axis from 07N to 12N. A tropical wave has its axis extending from 02N114W to 08N114W and to 16N113W. It is moving westward near 15 kt. This wave is surrounded by a moist and unstable environment. Scattered showers and isolated thunderstorms are within 120 nm west of the axis from 11N to 14N. Isolated small showers and thunderstorms are within 120 nm east of the axis from 07N to 11N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH...Corrected The monsoon trough axis extends from the far south-central Caribbean Sea near 13N73W westward to across far southern Nicaragua and to 11N86W to 10N110W to 14N125W to beyond 12N140W. Aside from the convection associated with the tropical waves discussed in the section above, scattered moderate to isolated strong convection is within 120 nm south of the trough between 105W-109W. Scattered moderate convection within 180 nm south of the trough between 102W-105W. 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. The earlier fresh to strong northwest winds over the northern Gulf of California have diminished as the strong high pressure north of the area over the Great Basin has weakened some. Over the Mexican offshore waters, the gradient associated with a high pressure ridge over those waters is allowing for mainly gentle to moderate northwest winds north of 20N, with seas in the range of 4-6 ft due to a mix of northwest and southwest swell. Light breezes persist south of 20N outside of the Gulf of Tehuantepec, with 3 to 5 ft seas in a southwest swell. For the forecast, gentle to moderate winds will persist elsewhere into mid-week. Looking ahead, seas will build off Baja California north of Cabo San Lazaro beginning late Tue as a northwest swell moves through the northern offshore waters. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Light to gentle north winds prevail north of the monsoon trough, while gentle to moderate southwest winds are to its south. Scattered showers and isolated thunderstorms are noted in the Gulf of Panama and offshore the border between Costa Rica and Panama. Seas over these waters are in the 4-6 ft range. For the forecast, seas off western Guatemala beyond 120 nm may peak to 8 ft into Mon in a mix of north swell from the Tehuantepec region and longer-period southwest swell. Elsewhere seas will average about 4 to 6 ft in SW swell. Fresh to northeast to east winds are expected in the Gulf of Papagayo Mon night and Tue. Scattered showers and isolated thunderstorms are expected to continue across the region through early next week. REMAINDER OF THE AREA... Moderate to locally fresh northeast winds continue over the waters north of the monsoon trough and west of 120W, with gentle to moderate winds south of the monsoon trough. Recent altimeter satellite data showed seas just below 8 ft due to a northwest swell north of 29N between 125W and 130W. An area of 8 ft in a northwest swell is evident from 07N to 09N between 106W-110W. These seas will subside to less than 8 ft by early Sun evening. Elsewhere, gentle to moderate north to northeast winds and seas in the 5-7 ft range will change little into early next week. A northwest swell expected to raise seas to 8 ft will move into the waters north of 27N between 120W-130W Tue into Wed then subside. Looking ahead, a more substantive area of northwest swell will accompany a cold front that will move into the waters north of 28N and west of 130W Tue night, with seas in excess of 8 ft dominating the waters northwest of a line from Guadalupe Island to 15N140W by late Thu. $$ Aguirre