000 AXPZ20 KNHC 302150 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2150 UTC Tue Jan 30 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 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Storm Warning: High pressure continues to build across eastern Mexico in the wake of a cold front. Winds are to storm force in Tehuantepec as verified by earlier scatterometer data and a nearby ship report. The area of high pressure dominating the Gulf of Mexico will start to shift eastward tonight, loosening the pressure gradient. Winds will diminish to gale force Wed, and fall below gale force early Thu. Please refer to the East Pacific High Seas Forecast under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more details. Looking ahead, another gale force wind event is possible Fri night into Sat. This next event will be much weaker and shorter duration than the current event. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 09N75W to 04N94W. The ITCZ continues from 04N94W to 07N120W to 08N140W. Scattered moderate to isolated strong convection was noted within 150 nm either side of the ITCZ W of 131W. Also, scattered moderate convection was noted within an area bounded by 23N110W to 16N98W to 07N107W to 11N116W to 23N110W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Please refer to the special features section above for more on the latest gap wind event. A large and broad wind field will extend well to the SW of the Mexican coastline, reaching near 09N102W this morning and afternoon. This will generate a large area of 10 to 20 plus ft seas in northerly swell across this area. Elsewhere over the open waters, seas are expected to remain at or below 6 ft through Sat as a tranquil pattern prevails. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Fresh to strong gap winds will increase to near gale force late tonight into early Wed over the Gulf of Papagayo. Elsewhere N of 09N, gentle to moderate offshore flow will strengthen through Wed, except pulsing to fresh to strong offshore of the Gulf of Panama and near the Azuero Peninsula through Wed night. Gentle to moderate S to SW winds will prevail S of 09N the next few days. REMAINDER OF THE AREA... High pressure N of the area has weakened, and the pressure gradient has loosened enough to diminish trades to 20 kt or less over the area. A mix of NE and NW swell continues to prevail with seas 8 ft or greater covering the waters within an area bounded by 23N110W to 16N98W to 07N107W to 11N116W to 23N110W, where seas continue to peak near 11 ft. Seas will gradually subside to 6-8 ft across the trade wind belt by midweek, then below 8 ft for the end of the week. Large swell generated from the latest Gulf of Tehuantepec gap wind event will propagate across the waters S of 14N and E of 120W, while gradually subsiding from the middle into the end of the week. $$ Lewitsky