000 AXPZ20 KNHC 221530 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1412 UTC Thu Nov 22 2018 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 1500 UTC. ...SPECIAL FEATURES... A Gale Warning is in effect with a surface trough in W central waters. The trough axis extends from 17N127W to 12N131W to 09N132W. The pressure gradient between high pressure of 1026 mb located W of area near 30N144W and this trough is supporting strong to minimal gale force N to NE winds from 13N to 17N W OF trough to 133W. A recent altimeter pass provides observations of 9-13 ft seas within the area of gale force winds. The trough will drift eastward over the next 24 hours as the high pressure also builds eastward across the forecast waters. An area of fresh to strong NE-E winds will persist on either side of the trough covering mainly the region from 10N-20N W of 120W during the next 48 hours. Please refer to the East Pacific High Seas Forecast under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from a 1010 mb low pressure near 10N76W to 08N87W to 07N98W. The ITCZ axis continues from 07N98W to 07N110W to 08N129W, then resumes from 09N135W to 07N140W. Scattered moderate and isolated strong convection is N of 06N between 78W-81W...including the Gulf of Panama. Similar convection is also noted from 07N-10N between 124W and 129W. A surface trough extends from 17N127W to 12N131W to 09N132W. Numerous moderate to isolated strong convection is noted from 14N-16N E of trough to 127W. Scattered moderate convection is seen elsewhere 14N-17N between 124W-130W, and also from 13N-14N between 130W-131W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec Gale Warning: Winds have diminished below gale force, and the Gale Warning is allowed to expire. Fresh to strong northerly winds will persist to Fri morning. Winds will become light and variable Fri afternoon through Sun. The next gap wind event across the Tehuantepec region is forecast late on Mon, likely reaching minimal gale force Mon evening through Tue morning. Seas will build to 11-12 ft with this event. Gulf of California: In the northern portion of the Gulf, gentle to moderate NW to N will follow in behind a weak cold front moving across the area later today. In the southern Gulf, gentle to moderate NW to N winds will increase to moderate to fresh late today through Fri night as a high pressure W of the Baja California Peninsula builds eastward. A cold front is already clipping the offshore forecast waters W of Baja California Peninsula. The front will continue to move eastward while dissipating. High pressure will build in the wake of the front, ushering in moderate to fresh NW winds through Fri night, increasing to fresh to locally strong N of 26N Sat, before diminishing as the gradient relaxes. Building seas in NW swell will accompany the increasing winds, with heights of 6 to 9 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A light plume of volcanic ash originating from the Fuego volcano in southern Guatemala is reaching the coast, however, the plume is not currently expected to extend far enough into the offshore waters to warrant an ashfall advisory. This will need to be monitored in case conditions change. For now, the forecast indicates that a light plume of volcanic ash will continue to reach the coast near 92W through tonight. Gulf of Papagayo: Fresh to locally strong NE winds with seas to 8 ft will diminish this afternoon, but will pulse again tonight into early Fri before becoming weaker during subsequent nights. Winds are forecast to increase back to fresh to strong starting Mon night. The monsoon trough will extend roughly along 08N/09N during the next few days with gentle to moderate NE winds N of the trough, and moderate to fresh SW winds S of the trough. Seas will be in the range of 4 to 6 ft mainly in mixed long-period SW and NW swell. REMAINDER OF THE AREA... Please see the Special Features section for information on the Gale Warning associated with a surface trough over the W central waters. A cold front extends from 30N120W to 22N130W, then continues as a dissipating front to 21N135W. Mainly gentle to moderate winds are observed on either side of the front. Seas of 8-11 ft in NW swell behind the front are covering the waters N of 22N W of a line from 30N125W to 22N130W. The front will weaken as it shifts E of the area, while the swell gradually decays through the weekend. A new and larger set of NW swell is expected to arrive early Mon, with seas building to up to 14 to 18 ft near 30N140W by late Mon night. $$ GR