000 AXPZ20 KNHC 141602 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sat Apr 14 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 1200 UTC surface analysis and satellite imagery through 1445 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Strong high pressure will build southward along the Sierra Madre Orientales and across the western Gulf of Mexico this afternoon through tonight, and create a very tight pressure gradient across SE Mexico. Northerly winds at 20-25 kt will begin to surge into the Tehuantepec region by tonight, building seas to around 9 ft. Then, winds are expected to rapidly increase to 30-40 kt by early Sun morning, and to 30-45 kt late in the afternoon. This event is expected to continue into early next week, while gradually diminishing. Seas as high as 18 or 20 ft are expected Sun night into Mon, before slowly subsiding early next week. In addition, an extensive swath of large N to NE swell generated by these northerly winds will propagate well to the SW of the Tehuantepec area, covering roughly the waters from 09N to 14N between 93W and 103W by early Mon morning. Climatologically speaking, the final winter season gale force wind event typically occurs across the Gulf of Tehunatepec in late March or early April. Please refer to the East Pacific High Seas Forecast under AWIPS/WMO headers HSFEP2/FZPN03 KNHC for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from 09N75W TO 09N92W TO 07N105W. The ITCZ continues from 07N105W TO 07N117W TO 05N140W. Scattered moderate isolated strong convection is noted within 300 nm N and 240 nm S of the trough. Scattered moderate to strong convection is noted within 240 nm N of the ITCZ. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate to fresh NW to N winds and large NW swell will prevail west of Baja California Norte today. An early morning altimeter pass indicated a broad area of seas 9-10 ft offshore of Punta Eugenia. Seas will gradually subside to 8-9 ft on Sun. Strong NW winds have spread down the full length of the Gulf of California overnight, and have generated high seas of 8 to 11 ft between 24N and 27N based on an early morning altimeter pass. High pressure over the Great Basin will continue to influence the region and produce strong NW winds through much of the Gulf through tonight before winds and seas diminish considerably Sun and then shift to the S on Mon. A late season Gulf of Tehuantepec gap wind event will be induced by a strong cold front moving across the Gulf of Mexico starting early on Sun. Please, see Special Features section above for details. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle winds are expected through the forecast period, with a weak surface through extending along 08-09N yielding light SW winds to its south. Seas in the 3 to 5 ft range will continue over most of the area. Fresh gap winds are likely in the Gulf of Papagayo tonight, and possible again early on Mon. REMAINDER OF THE AREA... The pressure gradient between lower pressure in the vicinity of the ITCZ and strong high pressure of 1031 mb centered N of the area near 35N130W is producing fresh to strong trade winds north of the ITCZ and west of 125W. The aerial extent of the trades will diminish late today as the high pressure moves SW and weakens some. Large NW swell is propagating southeastward through the forecast waters, with max seas of around 14 ft in the north-central waters based on overnight altimeter data. This swell will continue to propagate SE across the forecast waters, with seas of 8 ft or greater particularly W of 108W over the next 48 hours. A cold front will sweep into the NW waters on Sun. Fresh to locally strong N to NE winds will follow the front which is forecast to weaken over northern waters on Mon. $$ Stripling