000 AXPZ20 KNHC 011523 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1525 UTC Sun Oct 1 2017 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 1400 UTC. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends across Central America near 10N84W to 15N97W to 1008 MB low pres near 12N109W to 1008 MB low pres near 11N114W to 10N130W to beyond 10N140W. Scattered moderate to strong convection is within 270 nm S of the monsoon trough axis east of 101W. Scattered moderate convection is within 120 nm of either side of the monsoon trough axis between 105W and 118W, and W of 126W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Fresh gap winds over the Gulf of Tehuantepec will strengthen early this week as low pressure just southeast of the area develops and deepens. Seas will build to 7 to 8 ft by early Tuesday morning. Environmental conditions are expected to be conducive for gradual development of the area of low pressure while it moves slowly west- northwestward through the middle of the upcoming week. Also by the middle of the upcoming week, long period SW swell will increase seas to 8 to 10 ft by Wednesday night, and 8 to 12 ft by Thursday night over the offshore waters S of 20N. Elsewhere, a ridge dominates the waters west of the Baja California Peninsula producing gentle to moderate northerly winds and seas of 4 to 5 ft. Northerly swell are propagating into the waters west of Baja California Norte today, building seas to 8 to 9 ft, which are expected to last through Tuesday. Fresh to locally strong S-SW winds are expected over the northern Gulf of California tonight through Tuesday as low pressure develops over the area. Seas over the northern gulf will reach 6 ft during that time. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... An active monsoon trough is currently across Central America and adjacent waters with widespread convection. The trough will remain close enough to the coast, either inland or just offshore, to produce additional active convection over portions of Central America as well as the adjacent coastal waters during the next few days. As a result, very heavy rainfall will be possible over higher terrain of portions of central America early this week. Winds and seas are expected to increase over the forecast waters through the forecast period. Fresh to strong SW to W winds and seas of 8 to 11 ft are expected to affect the waters beyond 200 nm off the coast from Nicaragua to Guatemala beginning Monday morning through Thursday. Cross equatorial SW swell, with periods of 20 to 22 seconds are forecast to reach the waters between Ecuador and the Galapagos Islands Tuesday night, building seas to 7-8 ft by Wednesday night. The combined wind waves and swell will build seas to 9 to 13 ft offshore Costa Rica to Nicaragua by Thursday night. REMAINDER OF THE AREA... High pressure of 1027 mb is centered N of the area near 37N133W with a ridge axis that extends southeast to near the Revillagigedo Islands. The pressure gradient between the ridge and the monsoon trough is supporting mainly moderate to locally fresh NE winds north of the monsoon trough and west of 120W. One exception is that the pressure gradient between the area of high pressure and low pressure inland over the SW United States is producing fresh to strong winds mainly north of 28N between 120W and 127W. Northerly swell associated with these winds are beginning to propagate into the region, with seas peaking near 12 ft along 30N by early Monday. Seas greater than 8 ft will reach as far south as 25N between 119W and 131W by Monday night. Cross equatorial southerly swell will propagate across the waters south of 02N between 105W and 135W by Tuesday, with seas building to 8 to 10 ft. Late in the forecast period, forecast models continue to indicate the possible development of low pressure south of Tehuantepec, and then moving the system WNW toward the waters W of 105W late this upcoming week. $$ Latto