000 AXPZ20 KNHC 220932 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0932 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: An earlier scatterometer pass indicated northerly near gale force winds which are likely higher now with peak drainage flow along with a locally tight pressure gradient. Winds are forecast to diminish below gale force later this morning with fresh to near gale through early Fri before becoming light and variable through the weekend. The next gap wind event will commence Mon with winds increase back to near gale force Mon night into Tue. Seas will build to around 11 ft during the peak of the gap wind events. Gale Warning with Trough in W central waters: A trough axis extends from 17N127W to 14N130W to 12N133W. The pressure gradient between high pressure N of 21N and this trough is supporting the development of mainly fresh to strong trades, except gale force just NW to W of the trough axis as indicated by recent scatterometer data. The troughing will drift S as the high builds N of the area with gale force winds diminishing in the evening. Seas of 8 to 13 ft will accompany these winds. Fresh to strong trades and 8 to 10 ft seas will then persist the next few days. Weaker trades and subsiding seas are expected by the end of the weekend into early next week as the high to the N weakens. 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 northern Colombia near 08N75W to 08N90W to 07N97W. The ITCZ axis continues from 07N97W to 08N114W, then resumes from 08N122W to 07N130W to 07N140W. Scattered moderate and isolated strong convection is from 05N to 08N between 89W and 98W, from 06N to 08N between 115W and 120W, and also from 06N to 11N between 121W and 128W. An upper level trough and surface trough are supporting scattered moderate and isolated strong convection within an area bounded by 30N125W to 30N114W to 21N120W to 13N130W to 13N140W to 20N140W to 30N125W. Expect this activity to remain active through the day as the trough shifts eastward. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for information on the Gulf of Tehuantepec Gale Warning. Gulf of California: In the northern portion of the Gulf, light and variable winds will remain through the next few hours. 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. High pressure of 1024 mb is located W of the Baja California peninsula near 25.5N120W, supporting gentle to moderate anticyclonic winds around it across the waters W of 105W. A weakening cold front is forecast to move across these offshore waters through the day. High pressure will build eastward in the wake of the front, ushering in moderate to fresh NW winds through Fri night, increasing to fresh to locally strong N of 27N 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 plume of volcanic ash originating from the Fuego volcano in southern Guatemala is forecast to reach along 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. 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 trough from 17N127W to 14N130W to 12N133W. A cold front extends from near 30N121W to 23N130W, continuing as a weaker boundary to 21N140W. Strong high pressure is building E to SE behind the front, however winds are only gentle to moderate N of 21N. NW swell of 8 to 12 ft is across this area behind the front. 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 may arrive early Mon, with seas building to up to 14 to 18 ft near 30N140W by late Mon night. A surface trough is along the ITCZ from 10N116W to 06N121W. A recent scatterometer pass showed an area of fresh to strong winds along with 8 ft seas from 06N to 10N between 114W and 118W. Winds will diminish by 24 hours as the trough continues westward. $$ Lewitsky