000 AXPZ20 KNHC 302335 AAA TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2335 UTC Tue Mar 30 2021 Updated Special Features section 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 2300 UTC. ...SPECIAL FEATURES...Updated Gulf of Tehuantepec Gale Warning: Strong high pressure, in the wake of a Gulf of Mexico cold front, will build southward along the eastern slopes of the Sierra Madre Oriental Mountains beginning late Wed into Thu. The resultant tight gradient between it and lower pressure south of Mexico is expected to result in a surge of strong gale-force winds in the Gulf of Tehuantepec region starting late Wed night into Thu as a cold front quickly moves over the western Gulf of Mexico and across southeastern Mexico. These gale conditions are expected to continue into the upcoming weekend, diminishing to just below gale force Sun afternoon. Wave heights will build to 10-14 ft Thu and to 12-18 ft Fri and Fri night, before they begin to slowly subside Sat. Swell generated by this event will spread well to the southwest and west of the Gulf of Tehuantepec region through the weekend. Please read the latest HIGH SEAS FORECAST- https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from a 1008 mb low over northwestern Colombia southwestward to 07N78W to 06N80W to 08N85W and to 06N90W, where latest scatterometer data indicates that it transitions to the ITCZ to 04N105W to east of a trough near 06N119W. It resumes west of the trough at 06N125W to 05N134W and to beyond the area at 05N140W. Scattered moderate to isolated strong convection is within 120 nm north of the trough between 83W-87W. Scattered moderate convection is within 90 nm north of the ITCZ between 115W-118W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for details on an upcoming gap gale-force wind event in the Gulf of Tehuantepec region. Moderate to fresh north to northeast winds in the Gulf of Tehuantepec region will become light and variable later this afternoon and moderate south to southwest winds tonight. A small area of lingering wave heights to 8 ft is downstream of the Gulf of Tehuantepec. These wave heights will gradually shift westward away from the Gulf of Tehuantepec region through early Wed while subsiding to less than 8 ft. Wave heights are 4-6 ft elsewhere off southern Mexico south of Cabo Corrientes due to a S to SW swell, with light to gentle breezes. Farther north, gentle to moderate NW winds persist with wave heights of 3-5 ft seas in open waters with mixed SW and NW swell. For the forecast, strong gale-force winds are forecast for the Gulf of Tehuantepec region beginning late Wed night into early Thu as another cold quickly moves over the western Gulf of Mexico and across southeastern Mexico. Farther north, winds are generally light to gentle, but the recent arrival of a new set of NW swell will induce building wave heights primarily west of northern Baja California through Wed. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Strong NE to E winds are across the Gulf of Papagayo, with wave heights up to about 8 ft as well as downstream of the plume of these winds. They are combining with a component of longer- period SW swell. An Ascat pass from late this morning revealed gentle to moderate north winds through the Gulf of Panama. Elsewhere light to gentle winds continue over the Central American offshore waters with 3-5 ft wave heights. For the forecast, fresh to strong offshore gap winds will continue across Gulf of Papagayo region through the upcoming weekend. Wave heights will build from northern Costa Rica to Guatemala later in the week, due to seas generated from the Papagayo and Tehuantepec gap wind areas mixing with longer period SW swell. REMAINDER OF THE AREA... A nearly stationary upper-level low is identified on water vapor imagery to be near 25N126W. Mid to upper-level moisture is present to the east of the low. Broken mid to upper-level clouds streaming east-northeastward east of the low are noted from 25N to 31N between Baja California and 124W. Scattered showers are possible from 26N to 30N between 125W-128W. This mid to upper-level pattern is also supporting a surface trough farther south into the deep tropics that is analyzed from near 10N117W to 03N123W. This is also supporting an area of moderate to fresh trade winds to the west of the trough. An afternoon Ascat pass showed an area of fresh to strong trade winds farther west from 02N to 19N west of 128W. This area is south of a 1038 mb high pressure center analyzed well north of the area near 45N137W. Seas are 8 to 9 ft in these areas of trade winds, assisted by a component of SW swell. Farther east in the deep tropics, gentle to moderate winds are noted with wave heights of 4-6 ft due to a SW swell. A new set of NW swell has propagated into the north- central waters north of 28N and between 122W-133W, with wave heights of 8-10 ft. This set of NW will propagate through the north- entral waters into Thu, reaching south to near 26N. Maximum wave heights with this swell is forecast to reach the 8-10 ft range by early on Wed, then decay to less than 8 ft by early on Thu. For the forecast, farther east, wave heights will build to at least 8 ft from 05N to 10N between 95W and 110W due to an E swell generated from gap wind flow and persistent longer- period SW swell. $$ Aguirre