000 AXPZ20 KNHC 200254 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0235 UTC Mon Nov 20 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 0000 UTC surface analysis and satellite imagery through 0215 UTC. ...SPECIAL FEATURE... Gulf of Tehuantepec Gale Warning: Strong high pressure is surging down eastern Mexico while a cold front is moving through the SW Gulf of Mexico N of the area. While there have been no recent observations in the Gulf of Tehuantepec, available guidance indicates that gale force winds up to 40 kt are blowing across the Tehuantepec area. Winds may approach strong gale force during the overnight hours through around sunrise, then will diminish below gale force by Mon afternoon as the gradient significantly slackens. Seas will rapidly build to up to 17 ft during the strongest winds tonight. Northerly winds will pulse to fresh to near gale force Mon night, then will diminish to 20 kt or less Tue morning. Northerly flow will then pulse to fresh to strong starting Wed morning with another gale force wind event possible Wed night through Fri night. INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N75W to 06N90W to 09N106W. 09N106W TO 11N115W TO 10N130W TO 12N140W. The intertropical convergence zone axis extends from 09N106W to 11N115W to 10N130W to 12N140W. Scattered moderate convection is within an area bounded by 14N118W to 11N126W to 07N127W to 05N123W to 05N118W to 09N115W to 14N118W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section above for information regarding the Gulf of Tehuantepec Gale Warning. A NW to SE oriented ridge just beyond 250 nm seaward will maintain moderate to locally fresh NW flow W of the Baja Peninsula through the evening when the pressure gradient will relax, supporting moderate NW flow later tonight through sunrise Mon. Light N winds winds then are expected through Thu. A trough is forecast to form from the central Baja Peninsula southward, on Thu night and Fri, accompanied by a light W to NW wind shift. Expect seas in the 4 to 7 ft range today, with these conditions resuming again late in the week, with 3 to 5 ft seas during early and mid part of the week. Gulf of California: Fresh to strong NW winds across the gulf from 25.5N to 29N W of 110W will diminish by midnight as the pressure gradient relaxes. Moderate NW flow is then forecast across the entire gulf waters, becoming light by Mon evening. Moderate to locally fresh NW flow will resume across the entire gulf on Tue and Wed, then diminishing Thu through Fri. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Moderate to locally fresh NE drainage winds are forecast during the overnight hours tonight and on Mon night, then light drainage flow expected during the overnight hours through Thu night, with moderate to fresh nocturnal drainage resuming on Fri night. Light and variable winds and 3 to 5 ft seas are expected elsewhere to the N of the monsoon trough, which has been meandering between 09N and 11N. Moderate to locally fresh southerly winds and 4 to 7 ft seas are forecast S of the monsoon trough through the week. REMAINDER OF THE AREA... A tight pressure gradient is in place between a dissipating cold front W of 140W and ridging to the E across the northern waters. Associated scattered moderate convection is within an area bounded by 30N133W to 30N140W to 17N140W to 30N133W. The tight pressure gradient is supporting fresh to strong southerly flow in the NW corner of the discussion waters, along with 8 to 10 ft seas. Winds will increase to near gale force with seas also building to 12 ft by early Mon with a lengthening fetch area. The front will dissipate prior to reaching 140W. Additional cold fronts will approach 140W through the week, but will stall through Wed night as high pressure holds. A weakening front will manage to cross 140W by early Thu with an associated area of large NW swell intruding prior to its arrival. NW swell will build seas to 16 ft near 30N140W by Thu morning. The highest seas will decay through the end of the week, but the edge of seas of 8 ft or greater will manage to stretch across the waters N of 10N and W of 125W by Fri morning. Elsewhere, moderate to fresh trades are supporting 4 to 7 ft seas in mixed swell. Trades will diminish slightly early in the week as the overall pressure gradient weakens allowing for seas to subside to less than 6 ft. $$ Lewitsky