000 AXPZ20 KNHC 302157 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2105 UTC Fri Sep 30 2016 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 1800 UTC surface analysis and satellite imagery through 2145 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N85W to 10N91W to 11N99W to 11N104W. It resumes at 13N113W to 10N122W to 08N127W to low pressure near 12N135W 1012 mb to 12N140W. Scattered moderate isolated strong convection is within 180 nm south of the axis between 85W and 88W. Scattered moderate convection is within 180 nm south of the axis between 103W and 107W, and also within 60 nm of the axis between 90W and 95W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The weakening remnant low of Roslyn is centered near 24N117W with a pressure of 1015 mb. Latest satellite imagery depicts it as a low-level cloud swirl from 22N to 25N between 116W and 119W. It will dissipate by early Saturday afternoon. A weak pressure gradient over the forecast waters is supporting mainly light to gentle winds across the area. Earlier strong north winds that funneled through the Gulf of Tehuantepec during the overnight and early morning hours have diminished to moderate intensity. The resultant seas of 8 to 10 ft have subsided to 6 to 7 ft. However, the respite will be short-lived as the pressure gradient between high pressure ridging over central Mexico and surface trough over the eastern Bay of Campeche again tightens tonight. This will send another surge of strong north winds the isthmus of Tehuantepec and through the Gulf late tonight, and into Saturday morning with seas building to the range of 8 to 10 ft. Seas are in the 4 to 6 ft range north of 20N outside the Gulf of California, 6 to ft south of 20N, and 2 ft or less through all but the southern entrance to the Gulf of California. As the remnant low of Rosyln dissipates, high pressure will build across the region from the northwest through the weekend and strengthen the pressure gradient to the west of 110W. This will produce a modest increase in winds across the Pacific waters of the Baja California Peninsula. Associated northwest to north swell is forecast by wavewatch model guidance to spread into the northeast waters beginning early on Saturday with seas of 6 to 8 ft. The swell is expected to reach further south to near 26N by Sunday afternoon with seas building to around 9 or 10 ft. A surface trough is analyzed from 22N113W to low pressure near 17N113.5W to 13N113W. Scattered moderate to strong convection is occurring within 120 nm west of the trough and from 17N to 19N, and within 30 nm of a line from 18N110W to 19N111W. Scattered moderate convection is within 45 nm of 17N111W, and within 30 nm of a line from 15.5N113.5W to 13N114W. The trough will continue to move west-northwest through Sunday with low chances for development. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light and variable winds are expected north of the monsoon trough, while gentle to locally moderate south to southwesterly winds are expected south of the monsoon trough through the upcoming weekend. Combined seas of 4 to 7 ft, primarily in long- period southwesterly swell is expected across the offshore waters through the upcoming weekend. REMAINDER OF THE AREA... High pressure will build over the northern waters which will increase the pressure gradient, freshening winds north of the monsoon trough this weekend. The long fetch of these fresh trades will help build seas to the 7-9 ft range early next week. $$ AGUIRRE