000 AXPZ20 KNHC 222201 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Wed Nov 22 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 1800 UTC surface analysis and satellite imagery through 2130 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: Gale force NW to N winds have begun to spread southward across the Gulf of Mexico W of 95W behind a cold front now pushing into the far SW Bay of Campeche. Strong northerly winds will begin sweeping through the Chivelas Pass and across the Gulf of Tehuantepec. These winds will quickly reach 30 to 40 kt by this evening and increase further to 35 to 45 kt tonight into Thu. Gale force winds will spread farther downstream of the coast overnight to about 13N, and seas building to 16-17 ft, with winds then diminishing slightly into early Thu afternoon. Minimal gale conditions will then persist through mid morning on Fri then diminish to 20 kt or less late Sat morning. The resultant NE swell will propagate SW, mixing with long-period cross equatorial swell, with seas 8 ft or higher well downstream of the Gulf of Tehuantepec along 08N between 94W and 102W on Fri evening before beginning to subside. Looking ahead, Strong N winds are forecast to resume again on Sat evening with Gale conditions from sunrise Sun and continuing through sunrise on Tue. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from low pres near 11N76W 1010 MB across Panama to 08N85W TO 10N95W, then transitions to ITCZ near 10N107W and continues through 08N125W to 09N130W to 10N140W. Scattered moderate convection was across far eastern portion of the basin from 07N to the coast of Panama and E of 83W. Scattered moderate to strong convection was noted within 60 nm of a line from 21N135W to 18N136W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... See Special Features paragraph above for information on the developing Gulf of Tehuantepec Gale Warning. A NW to SE orientated ridge axis extends from a 1022 MB high near 32N125W through 19N115W, or about 250 nm seaward of the Pacific coast of Mexico. This ridge will only be interrupted by a weak surface trough extending S from the central Baja Peninsula to near 20N112W, and is expected to persist through Fri night before filling. Expect seas of 3 to 4 ft seas at 12 seconds W of Baja through Thu morning, except near 2 ft nearshore, then building in new NW swell at 14 to 15 seconds Fri, peaking at 4 to 7 ft across the waters W of Baja Fri night. Seas will then gradually subside some Sat into Sun. Long- period NW swell in the form of 7 to 9 ft seas will reach 30N120W on Sun night, and spread S across the waters W of Baja with 8 to 13 ft seas at 17 to 19 seconds forecast W of Baja late Mon night. Gulf of California: Moderate to fresh NW flow prevails across across all but southern portions of the gulf this morning as high pressure is building across N Mexico behind a cold front. Winds will diminish slightly this evening through Thu night as the ridge shifts SE. The pressure gradient will then relax further, with light and variable winds on Fri through Mon. Strong to near gale NW flow expected N of 30N late Mon night, with gale conditions possible on Tue afternoon with seas building to 10-11 ft across the long fetch waters. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Fonseca...Fresh NW winds forecast to begin around sunrise on Mon. Gulf of Papagayo: Fresh to locally strong NE nocturnal drainage flow forecast to begin on Thu night into early Fri afternoon, and then resume on Fri night and continue through Tue with strong winds are expected to reach as far SW as 09N91W. Light and variable winds, and 3 to 5 ft seas, are expected elsewhere through Sun to the N of the monsoon trough which has been meandering between 09N and 11N, while moderate southerly winds, and 3 to 6 ft seas, are forecast S of the monsoon trough. REMAINDER OF THE AREA... A NE to SW aligned ridge will meander from 32N125W to 25N134W for the next several days. SW winds currently across the waters N of 30N W of 135W have moderated in the presence of a surface trough extending from 30N134W to 21N140W. A cold front has entered the far NW portion of the area. This front is expected to move to near 30N137W to 27N140W and stall through Fri as elongated low pressure develops along the front. The front will usher in long period NW swell into the far NW corner of the area tonight and Thu with seas building to 9 to 15 FT at 14 to 16 seconds late tonight. This NW swell, in the form of 8 to 11 ft seas at 12 to 17 seconds, will propagate across the waters W of a line from 32N122W to 14N140W on Thu night before beginning to subside. Another cold front will move E in to the area reaching from 32N133W to 25N140W early Sat with 8 to 11 ft seas at 12 to 17 seconds in the wake of the front. $$ Cobb