000 AXPZ20 KNHC 220950 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 417 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 0600 UTC surface analysis and satellite imagery through 0945 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: Strong N winds will develop this afternoon and quickly increase to 30 to 40 kt gale force this evening, with these conditions continuing into early Thu afternoon. Minimal gale conditions will then persist through mid morning on Fri. Winds will diminish to 20 kt or less late Sat morning. Expect max seas of 17 ft near 14N96W late Thu. 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 09n between 96W and 104W on Fri evening before beginning to subside. Strong N winds are forecast to resume again on Sat evening with gale conditions at sunrise on Sun and continuing through sunrise on Tue. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends W between 09N and 11N across the SW Caribbean to the Pacific coast of Panama and Costa Rica at 10N85W and continues W to 09N100W where scatterometer winds indicate a transition to an ITCZ, which continues W to 07N114W to 12N140W where it loses identity with a surface trough analyzed just W of 140W. Isolated moderate to strong convection is noted within 60 nm either side of a line from 08N81W to 07N89W, within 120 nm of 10N130W and 12N137W. ...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 extending about 250 nm seaward of the Pacific coast of Mexico will be interrupted today as a trough forms extending SW from the central Baja Peninsula to near 23N116W, and continues through Fri night before filling. Expect seas in the 2 to 4 ft seas at 12 seconds W of Baja through Thu morning, then building from the NW with 4 to 7 ft seas at 14 to 15 seconds across the waters W of Baja on Fri night, subsiding some on 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: Gentle to moderate NW flow expected through Thu night. The pressure gradient will then relax, with light and variable winds on Fri through Mon. Strong to near gale NW flow expected N of 30N on Mon night, with gale conditions possible on Tue afternoon with seas building to 10 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 21N138W for the next several days. Scattered showers are possible under a dense cirrus shield within 60 nm either side of a line from 30N133W to 25N137W. Strong SW winds, currently across the waters N of 30N W of 135W, will diminish to 20 kt or less by this afternoon as the ridge weakens allowing a cold front to reach 32N140W on Wed. The cold front will stall from 32N137W to 23N140W on Thu with a surface low developing along the front near 30N140W on Thu night. The low will move NE of the area late Fri night. Combined seas of 8 to 13 ft currently across the discussion waters W of a line from 32N130W to 27N140W will build to 8 to 15 ft at 14 to 15 seconds late tonight. This long period 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 14 ft seas at 12 to 17 seconds in the wake of the front. $$ Nelson