000 AXPZ20 KNHC 181604 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Fri Sep 18 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...TROPICAL WAVES... A tropical wave axis is along 118W from 05N to 16N, moving west at 10 to 15 kt. It shows up well in the lower half of the atmosphere, southwest of a upper level ridge. Scattered moderate convection is noted within 60 nm of the wave axis. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A segement of the monsoon trough extends from 11N87W to 19N105W to 13N104W. Another segment extends from 20N110W to 10N120W to 14N125W to a 1009 m low near 13N140W. Scattered moderate isolated strong convection is noted from 13N to 16N between 100W and 105W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Weak deep layer ridging is observed between Baja California and about 125W, building east of the remnant low pressure over Karina which is slowing dissipating well west of the area. This ridge will build slightly through Sat as a trough north of the area moves into southern California. This pattern is supporting moderate to fresh winds off Baja California Norte along with combined seas to 7 ft. Winds and seas will diminish by Sun into early next week as the ridge weakens. The monsoon trough extends northward to near Cabo Corrientes. Pressure is starting to lower, and low pressure may be starting to form southwest of Cabo Corrientes along the monsoon trough. This may support fresh winds off the coast of Jalisco by Sun. Farther south, fresh to strong winds may pulse in the Gulf of Tehuantepec region by Sat night. Elsewhere, a weak pressure pattern across the region will result in mainly gentle to moderate winds and slight seas. Weak high pressure well west of Baja California Norte is supporting moderate northerly winds and 5 ft seas across the offshore waters. This synoptic pattern will continue through Sun. Northerly 6-7 ft swell will build southward toward Baja California Norte this weekend. A weak surface trough will develop well to the west of Baja California Sur this weekend, which will maintain light to gentle winds and slight seas through early next week. Farther south, strong gap winds and building seas are possible in the Gulf of Tehuantepec region on Sun, related to developing Tropical Depression Twenty Two in the southwest Gulf of Mexico. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gentle to moderate S to SW winds persist south of the monsoon trough. Elsewhere, gentle winds prevail north of the monsoon trough. Combined seas are currently in the 5 to 6 ft range in a mix of wind waves and southerly swell, with a maximum of 6-7 ft near Panama. The swell is starting to subside, and sea heights are expected to diminish today. REMAINDER OF THE AREA... The remnant low of Karina is located near 23N127W with a central pressure of 1010 mb. The most recent scatterometer data showed fresh winds north-northeast the low. Maximum seas are about 8 ft within 60 nm of the low. The low will continue to move westward and gradually weaken to a surface trough later today or tonight, and seas will subside below 8 ft tonight. An earlier altimeter satellite pass indicated seas near 8 ft just north of a 1009 mb low pressure area along the monsoon trough near 13N140W. Winds are likely near 20 kt within 120 nm north of the low. Winds and seas associated with the low will shift west of the area later today. A small cluster of scattered showers and thunderstorms is noted near the low pressure. Farther east, seas are 7 to 8 ft in an area along the monsoon trough from 06N to 10N between 105W and 115W, a combination of moderate to fresh SW winds along with longer period SW swell. Winds and seas will diminish later today in this area. $$ Christensen