000 AXPZ20 KNHC 232150 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Thu Sep 23 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 1800 UTC surface analysis and satellite imagery through 2030 UTC. ...TROPICAL WAVES... The axis of a tropical wave is along 118W from 05N to 20N, moving west at 10 to 15 kt. Associated convection is occurring near the monsoon trough and south of 14.5N, is described below. A 1009 mb low pressure center is near 19N124W and is accompanied by active convection this afternoon. Scattered moderate isolated strong convection is noted within 240 nm the NE and 210 nm SW semicircles. This system is forecast to move over cool waters and into an environment of stable air and strong upper- level winds, which should inhibit further development. A tropical wave is analyzed along 137W from 10N to 18N, moving westward at 10 to 15 kt. Associated active convection is confined to along the ITCZ and is described below. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from low pressure near 10N76.5W 1009 mb to 08.5N86W to 11N96W to 13N121W. The ITCZ begins near 11N126W to 09.5N135W to beyond 11N140W. Scattered moderate to strong convection is from 05N to 10N E of 87.5W, and within 30 nm N and 180 nm of the ITCZ W of 127W. Scattered moderate convection is from 07N to 14.5N between 90W and 118W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Strong northerly gap winds to around 25 kt continue across the Gulf of Tehuantepec this afternoon and downstream to near 12.5N97W. Peak seas have subsided to around 9 ft. These winds are being forced by high pressure across eastern Mexico behind an early season cold front across the Gulf of Mexico. Elsewhere, a ridge continues to extend over the offshore forecast waters of Baja California providing mainly light to gentle NW to N winds as shown by midday scatterometer data. Locally moderate NW winds are mainly along the coast and seas across the area remain 4 to 6 ft. Light to gentle winds are also in the Gulf of California and across the SW Mexico offshore waters, except for moderate southerly winds in the far northern Gulf. Seas are in the 3 to 5 ft range for the SW Mexico offshore waters and up to 3 ft in the Gulf of California. Northerly gap winds will continue across the Tehuantepec region through Sunday, pulsing to strong each late night and early morning. Surface ridging will continue to dominate the offshore forecast waters of Baja California supporting mainly gentle to moderate NW to N winds through Mon. Light to gentle winds will dominate over the SW Mexico offshore waters. Otherwise, a surface trough will move across the northern Gulf of California and will support fresh to strong southerly winds through early this evening. After that, mainly light and variable winds are expected across the entire Gulf through Mon. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gentle to moderate west to southwesterly winds will continue across the offshore waters of Costa Rica, Panama, Colombia and Ecuador today, then will diminish to light to gentle through Sat. Winds will increase again to gentle to moderate Sat evening and continue through early next week. Light to gentle variable winds are forecast for the offshore waters N of 10N with pulses of moderate NE to E winds in the Gulf of Papagayo over the weekend. Cross equatorial SW swell will reach the forecast area early Sat, building seas to 6-7 ft across the regional waters through the weekend. REMAINDER OF THE AREA... The northern forecast waters west of 120W remain under the influence of a surface ridge anchored by 1026 mb high pressure centered near 36N140W. The pressure gradient between the ridge and low pres center near 19N124W supports an area of moderate to locally fresh NE winds roughly from 19N to 25N between 120W and 130W, and from 16N to 22N west of 130W. Seas are generally 7-9 ft across this zone in mixed wind waves and NW swell. Winds across this area will gradually diminish over the weekend as the low shifts westward and weakens. Looking ahead, a cold front is expected to move into the NW waters early Tue and quickly weaken as it moves southward. Associated NW swell is expected to raise seas to 8-10 ft. $$ Stripling