000 AXPZ20 KNHC 100954 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 537 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 0600 UTC surface analysis and satellite imagery through 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A cold front currently moving across the Gulf of Mexico is expected to reach the Bay of Campeche by early this morning, and allow northerly winds behind the front to spill through the Isthmus the Tehuantepec and across the Gulf of Tehuantepec. Winds across this Pacific waters are forecast to reach gale force by around 1200 UTC. Then, winds will further increase to 35-40 kt by early this evening. Seas are expected to build in and downstream of the Gulf up to 13-14 ft with the strongest winds. Winds will diminish below gale force by Sun morning, then further diminish to 20 kt or less by early Mon morning. The most recent scatterometer pass already shows northerly winds of 20-30 kt N of 15N between 94.5W and 95.5W, including the Gulf of Tehuantepec. Looking ahead, the GFS global model continues to suggest a gale to minimal storm force gap wind event across the Gulf of Tehuantepec on Tue. This will be associated with a strong cold front moving across the western Gulf of Mexico. Winds are forecast to reach minimal gale force by Tue morning, then suddenly increase to 40-45 kt by early Tue afternoon as a strong high pressure of 1037 mb 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 forecast to reach near 50 kt by early Tue evening. Seas are expected to build up to 26-28 ft by Tue night. Currently, the GEFS probabilities of storm force winds reach 40 percent. Gap wind events that occur in the Gulf of Tehuantepec are the most frequently observed storm-force (48 kt or greater) wind events that occur outside of tropical cyclones in this region. ...TROPICAL WAVES... The axis of a tropical wave is relocated near 103W N of 09N. Isolated showers are near the southern end of the wave axis. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N76W to 09N90W to a 1010 mb low near 09N103W to 10N113W. The ITCZ extends from 10N120W and continues beyond 07N140W. No significant convection. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of California: High pressure over the Great Basin region is producing fresh to strong NW across the Gulf N of 30 with seas less than 8 ft. The high pressure will shift eastward today which will help winds to diminish to 20 kt or less by this afternoon. Strong high pressure will build again north of the area on Monday, resulting in fresh to strong winds N of 30N beginning Sun evening. Fresh to strong winds will spread south across the entire length of the Gulf 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. A ridge dominates the offshore forecast waters W of Baja California producing mainly a light to gentle anticyclonic flow and seas of 4-5 ft. These marine conditions will persist through Sun. Strong high pressure will build over the SW of United States and Mexico on Monday. Strong winds in the northern Gulf of California will funnel across Baja California Norte into the Bay of Sebastian- Vizcaino and other regions west of the Baja California Peninsula Mon evening into Tue. 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 beginning tonight. Otherwise, light to gentle winds are forecast north of the monsoon trough, and gentle to moderate southwest winds are expected south of the monsoon trough. Cross equatorial long period SW swell will keep seas in the 6-7 ft range between Ecuador and the Galapagos Islands this weekend 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 the Revillagigedo Islands. Moderate trades are noted N of the ITCZ and west of 130W. A weak trough extends from 16N116W to 09N118W. Isolated showers are where the trough meets the ITCZ. A swirl of low clouds is near 17N119W. $$ GR