000 AXPZ20 KNHC 261002 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue Mar 26 2019 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 0830 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A strong north to south pressure gradient is developing across southern Mexico this morning. High pressure is building across the western Gulf of Mexico and eastern Mexico. The gap winds are forecast to funnel through the Chivela Pass, and reach gale-force on Tuesday morning. North to northeast winds are expected to continue pulsing to gale force from Tuesday through Thursday. The wind speeds will be approaching strong gale force during the late night and early morning hours. The sea heights will peak around 18 feet on Wednesday morning. The swell that will be generated by this event will propagate to at least 100W, before mixing with swell from the northwest and from the south. The gale-force wind conditions will diminish by Thursday afternoon. The wind speeds will become fresh on Friday, and then become light and variable from Friday afternoon until the end of the period. The sea heights will diminish to 8 feet or less, as high pressure shifts east-northeast away from the region. Please read the latest High Seas Forecast issued by the National Hurricane Center under AWIPS/WMO headers FZPN03 KNHC/HSFEP2 or at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for specific marine details related to this event. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from the coast of Colombia near 07N78W to 07N82W to 06N87W. The ITCZ continues from 06N87W to 02N106W to 02N127W, beyond 06N140W. Scattered strong rainshowers are from 03N to 04N between 130W and 131W, and from 04N to 06N between 133W and 137W. Scattered moderate to isolated strong rainshowers are within 90 nm N of the ITCZ between 131W and 133W, and within 360 nm N of the ITCZ W of 136W. Isolated moderate rainshowers are elsewhere, within 30 nm on either side of the surface trough between 82W and 84W, within 120 nm to the north of the ITCZ between 88W and 91W, and from the Equator to 10N from 110W westward. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Please refer to the Special Features section for details about the Gale-force wind conditions that are forecast to begin today on Tuesday at 26/1200 UTC. Gale- force winds will stop around noon on Thursday. Winds at speeds ranging from 20 to 25 knots, and sea heights of 8 feet, will stop on Friday around noon. Expect gentle breezes for the rest of the time period, ending on Monday night. Gulf of California: S of 28N: moderate NW winds from now until the late morning hours, slowing down and becoming moderate from this afternoon until Tuesday night, becoming light and variable until Thursday morning, becoming NW moderate until Saturday afternoon, slowing down slightly on Saturday night, becoming fresh to strong on Sunday night, and remaining fresh until Monday night. The sea heights generally will be in the range of 2 to 4 feet. The surface pressure gradient, that exists between a 1021 mb high pressure center that is near 27N123W, and lower pressure in the interior of Mexico, will maintain moderate to locally fresh northwest to north winds in the offshore waters that are to the west of the Baja Peninsula through Wednesday night. Peak seas west of Baja California Sur are at 9 ft. Northwest swell propagating through these waters will decay gradually through midweek, as the sea heights subside to less than 8 feet by Wednesday. A stronger high pressure system will build toward the region on Thursday. Fresh to strong NW to N winds are expected in the Baja California Norte offshore waters from Thursday night through Friday night, with seas building to 8-10 feet. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Strong to near gale force northeast to east winds will continue pulsing in the Gulf of Papagayo through Saturday morning. The fastest wind speeds will occur during the late night and early morning hours as the nocturnal drainage flow enhances the wind speeds. The sea heights will build to 10 feet by Wednesday morning, and to 11 ft on Thursday morning. NE swell will propagate well downstream from the Gulf of Papagayo through Friday night. Gulf of Panama: Moderate to fresh north to northeast winds in the Gulf of Panama will strengthen to fresh to strong speeds on Tuesday night. The wind speeds will slow down to fresh, from Thursday night until Friday afternoon, and continue from moderate to fresh from Friday afternoon until Sunday morning. Expect moderate to fresh northerly winds for the rest of the time period. The sea heights will build to 8 ft downstream of the Gulf from Wednesday through Thursday morning. Cross- equatorial SW swell will be mixing with the NE wind waves. Southern hemisphere swell will continue to impact the region between Ecuador and the Galapagos Islands. The sea heights will build to 8 ft well offshore by Wednesday, as another set of long- period southwest swell crosses the region. Light to moderate winds will remain through this week, elsewhere. REMAINDER OF THE AREA... A stationary front currently is along 30N126W to 22N140W. The sea heights range from 8 feet to 12 feet. A cold front will move across the northwest waters from Tuesday through Wednesday, near 30N124W 25N130W 22N140W on Wednesday morning. This front will introduce another set of long-period northwest swell. A second cold front will stall just to the northwest of the forecast area from Thursday night into Friday. Another set of long-period northwest swell will propagate through the far northwest waters at that time. An enhanced surface pressure gradient, between high pressure that is centered near 28N125W and the ITCZ, is supporting fresh NE to E trade winds, from 06N to 16N from 120W westward. Altimeter data from Mon night and early Tuesday show peak sea heights to 9 feet and 10 feet. It is likely that this is a combination of long period northwest swell and shorter period northeast wind waves. These trade winds will diminish briefly on Tuesday and Tuesday night as high pressure weakens. Stronger high pressure on Thursday will build north of 30N on Thursday, and persist through Friday night. NW swell propagating across the high seas domain is maintaining seas of 8 ft or greater in the waters that generally are to the north of 01N and to the west of 104W. The northeast swell generated by the gap winds that are in the Gulf of Papagayo and in the Gulf of Tehuantepec will merge with northwest swell and long period cross-equatorial S to SW swell from Tuesday through Friday night. This will result in a large swath of 8-10 ft seas encompassing an area generally south of 15N and west of 91W to beyond 140W during the later part of the week. $$ mt