000 AXPZ20 KNHC 110926 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 549 UTC Sun Nov 11 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 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A tight pressure gradient with a ridge along the eastern slopes of the Sierra Madre Mountains in Mexico and lower pressure S of the region, combined with a front over the western Gulf of Mexico is supporting minimal gale force northerly winds across the Gulf of Tehuantepec with seas of 12-14 ft. Winds will diminish below gale force late this 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 minimal storm force (48-50 kt) by early Tue evening. Seas downstream of the Gulf of Tehuantepec are expected to build up to 22-24 ft by Tue night. Storm force winds are likely to persist through Wed evening, with gale force winds likely lasting into early Fri morning. ...TROPICAL WAVES... The axis of a tropical wave is located near 108W N of 09N. Scattered moderate convection is on either side of the wave axis but mainly from 11N to 13N between 105W and 112W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 07N103W to a 1010 mb low pressure located near 08N114W to 10N122W. The ITCZ extends from 10N128W to beyond 07N140W. A cluster of moderate to isolated strong convection is noted S of the ITCZ axis to 03N and W of 136W. Similar convection is seen from 06N to 09N between 134W and 137W. A diffluent pattern aloft is helping to induce this convective activity. ...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: Strong high pressure will 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 8-10 ft before starting to subside Tue morning as the ridge slightly shift eastward. Mainly light to gentle winds and seas of 3-5 ft prevail over the offshore waters W of Baja California. 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 over northern Baja California near 29N115W Mon night into Tue, with fresh to strong NE winds blowing across the offshore waters N of Cabo San Lazaro. Seas are forecast to build to 8-9 ft with these wind speeds. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to occasionally strong winds will pulse over the Gulf of Papagayo through Mon morning, with moderate to fresh winds thereafter. Winds will increase back to fresh to strong by Wed night as a tight pressure gradient develops over northern Central America behind a strong cold front moving into the NW Caribbean. Seas are forecast to build to 9 ft by early Thu morning. A strong Tehunatepec gap wind event W of the area is forecast to spread strong to near gale force winds and building seas of 12-20 ft into the far SW portion of the offshore waters of Guatemala and El Salvador, particularly W of 93W or 94W, Tue night through Wed. 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 reaching the waters near the Azuero Peninsula by early this morning. REMAINDER OF THE AREA... High pressure located well N of the area extends a ridge SE across the forecast waters to near 22N116W. A weak surface trough is noted from 09N127W to 19N120W. Isolated moderate convection from 07N to 09N between 126W and 130W. The trough is forecast to drift W while gradually dissipating. The pressure gradient is forecast to tighten Mon night into Tue morning resulting in fresh to locally strong trades just N of the ITCZ. Seas of 8 to 9 ft will be associated with these winds covering roughly the waters from 10N-16N between W of 120W by Tue afternoon. A cold front will attempt to approach 30N140W the next few days, but will stall and weaken just WNW of the area. A set of NW swell associated with this front is forecast to reach the NW waters by early Wed, with seas of 8-10 ft covering much of the waters N of 10N W of 130W by early Thu. $$ GR