000 AXPZ20 KNHC 102133 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2133 UTC Sat Nov 10 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 1800 UTC surface analysis and satellite imagery through 2030 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight pressure gradient with high pressure ridging along the eastern slopes of Mexico and lower pressure S of the region, combined with a cold front moving through the Gulf of Mexico N of the area is supporting gale force northerly winds as measured by a recent scatterometer pass. Seas are expected to build in and downstream of the Gulf of Tehuantepec up to 12-14 ft through tonight. Winds will diminish below gale force late Sun morning, then further diminish to 20 kt or less by early Mon morning. Looking ahead, model guidance continues to suggest an upcoming storm force gap wind event in the Gulf of Tehuantepec. This will be associated with a strong cold front moving across the western Gulf of Mexico. Winds are forecast to first reach minimal gale force by Tue morning, then suddenly increase to 40-45 kt by early Tue afternoon as a strong high pressure over NE Mexico extends a ridge southward across the Mexican coastal plains. A very tight pressure gradient across the Isthmus of Tehunatepec is forecast to support these very strong winds, which are forecast to reach storm force/50 kt by early Tue evening. Seas are expected to build up to 26-28 ft by Tue night. Storm force winds are likely to persist through Wed night, with gale force winds likely lasting into early Fri morning. Note that gale force winds are likely to spread into the offshore waters zone of Guatemala W of 94W. ...TROPICAL WAVES... The axis of a tropical wave is located near 107W N of 08N. Scattered moderate convection is W of the wave axis from 09N to 11N between 111W and 115W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N75W to 09N100W to 10N120W. The ITCZ extends from 10N120W to 08N134W. A trough axis extends from 09N134W to 04N140W. Scattered moderate and isolated strong convection is within 60-90 nm either side of the axis between 120W and 131W, and from 04N to 07N between 132W and 140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section for information on ongoing and upcoming Gulf of Tehuantepec gap wind events. Gulf of California: Winds are diminishing and will become variable tonight. Strong high pressure will then build again N the area Sun night and Mon, resulting in fresh to strong winds N of 30N beginning Sun evening. Fresh to strong winds will spread S across the entire length of the Gulf of California and likely across the waters between Las Marias Islands and Los Cabos by Mon evening. Seas are forecast to build to 8-9 ft before starting to subside Tue morning as the ridge slightly shift eastward. Weak inverted troughing extends from SE to NW across the offshore waters W of Baja California with high pressure ridging W of there. Mainly light to gentle onshore flow and seas of 3-5 ft prevail over these offshore waters and will persist through Sun. Strong high pressure will build over the SW of United States and Mexico Sun and Mon. Strong winds in the northern Gulf of California will funnel across Baja California Norte into and N of the Bay of Sebastian-Vizcaino and other regions W of the Baja California Peninsula Mon evening into Tue. Model guidance indicates the potential for minimal gale force winds near 29.5N115W late Mon night into Tue with the enhanced funneling from the northern Gulf of California. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see the Special Features section for information on an upcoming gap wind event. Fresh to occasionally strong winds will pulse over the Gulf of Papagayo beginning tonight through Mon morning, with moderate to fresh thereafter. Winds will increase back to fresh to strong by Wed afternoon as a tight pressure gradient develops due to a strong cold front moving into the NW Caribbean Sea N-NW of the area. Otherwise, light to gentle winds are forecast N of the monsoon trough, with gentle to moderate SW winds S of the monsoon trough through the next several days. Cross equatorial long period SW swell will keep seas in the 6-7 ft range between Ecuador and the Galapagos Islands this weekend into early next week, reaching the waters near the Azuero Peninsula by early Sun morning. REMAINDER OF THE AREA... High pressure of 1034 mb located well N of the area extends a ridge SE across the forecast waters to near 22N123W. A weak surface trough is noted from 13N121W to 19N120W. Scattered moderate convection is noted from 17N to 19N between 116W and the trough axis. Meanwhile, mainly light to moderate trades and 5-7 ft combined seas prevail across the open waters. The trough is forecast to drift W while gradually dissipating. The pressure gradient is forecast to tighten Mon night into Tue morning with trades increasing to moderate to fresh just N of the ITCZ. A cold front will attempt to approach 30N140W the next few days, but will stall and weaken just W-NW of the area. A set of NW swell is likely to pass SE of 30N140W by early Wed, with seas of 8-10 ft covering much of the waters W of 130W by early Thu. $$ Lewitsky