000 AXPZ20 KNHC 220322 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 204 UTC Sat Dec 22 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A ridge across the eastern slopes of the Sierra Madre mountains continues to support a gale force gap wind event across the Gulf of Tehunatepec. The most recent scatterometer pass shows an area of 30-40 kt winds extending downwind to about 12N96W while winds of 20-30 kt are covering a large area N of 10N between 93W and 99W. Seas of 10-14 ft are associated with these winds. Gale force winds will persist through tonight, then diminish on Sat as high pressure north of the area shifts eastward. Gale conditions are expected again across the Tehunatepec area Sun night into Mon. Please refer to the latest high seas forecast issued under AWIPS/WMO headers HSFEP2/FZNPN03 for more specific marine details. Gulf of Papagayo Gale Warning: High pressure building in behind a cold front that currently extends from eastern Cuba to northern Costa Rica is tightening the pressure gradient over northern Central America. Winds have already increased to 20-30 kt. As the gradient continues to tighten, these winds will further increase to minimal gale force by later tonight, with seas building in the 9 to 12 ft range in and downstream of the Gulf. These winds are then forecast to diminish to below gale force by early Sat afternoon, then increase again to minimal gale force by Sat night. Liberia, located near the Gulf of Papagayo, was reporting sustained winds of 20 to 25 kt with gusts to 34 kt. Fresh to strong winds are expected across the Gulf of Papagayo most of the forecast period. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from the coast of Colombia near 05N77W to 04N95W. The ITCZ continues from 04N95W to 07N115W to beyond the area at 06N140W. Isolated to scatterted moderate convection is noted from 07N to 13N between 107W and 116W. An upper-level low supports this convective activity. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features Section above for information on the ongoing strong gale force gap wind over the Gulf of Tehuantepec. Long period NW swell continues to propagate across the offshore forecast waters. Seas of 8 ft or greater cover much of the open ocean waters in the discussion area. Seas, everywhere outside the Gulf of Tehunatepec, will begin to subside late tonight into Sat. The next round of large swell is forecast by Wave model guidance to reach the offshore waters of Baja California Norte by early on Mon, and the remainder of the Baja California Peninsula offshore waters by early on Tue. The guidance depicts seas to build to the range of 12 to 16 ft N of Punta Eugenia on Tue. At that time, fresh to strong NW winds are also forecast to affect the offshore waters N of 26N by early Tue afternoon. Gulf of California: Winds are light and variable across the area with a trough meandering along the west coast of mainland Mexico. These conditions will persist during the upcoming weekend. Minimal gale force winds are possible across the northen Gulf of California on Tue as a strong low pressure settles over the SW of United States. Seas are forecast to build to 6 to 9 ft with these winds. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please the Special Features Section for more on the upcoming gale force gap wind event over the Gulf of Papagayo. Strong north winds will begin to over the Gulf of Panama beginning late tonight and are expected to last through Sun night, with seas starting at less than 8 ft but building to 8 ft by early on Sun. Elsewhere, gentle to moderate winds will persist, with seas in the 4 to 7 ft range. REMAINDER OF THE AREA... A weakening stationary front is analyzed from 30N128W to 25N140W. The front will become diffuse tonight as high pressure behind builds southeast and south. The pressure gradient between the high pressure and lower pressure present in the tropics has initiated an area of fresh to strong northeast trades from 09N to 15N west of 136W along with seas in the range of 10 to 12 ft due to the northwest swell combining with the wind waves. This area of trades will change little through late tonight, then expand north and east Sat through early next week. Seas of 9 to 11 ft will persist in association with the area of trade winds due to long period NW swell and wind waves. Northwest swell propagating across much of the forecast waters is begining to decay tonight. An area of mixed swell will develop south of about 14N or 15N between 90W and 110W on Sat as lingering NW swell mixes with shorter period northeast swell from the Tehuantepec and Papagayo gap wind events. $$ GR