000 AXPZ20 KNHC 311544 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Sun Mar 31 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 1200 UTC surface analysis and satellite imagery through 1430 UTC. ...SPECIAL FEATURES... ...GULF OF TEHUANTEPEC GALE WARNING... A short duration gale-force gap wind event is expected across the Gulf of Tehuantepec late tonight into early Mon morning as a strong high pressure ridge builds southward over eastern Mexico behind a Gulf of Mexico cold front. The front will reach the western Bay of Campeche this evening, with strong northerly winds then quickly beginning to spill through the Isthmus of Tehuantepec. Northerly winds are expected to increase to gale force across the Gulf of Tehuantepec within a few hours of the onset of north winds. Seas will quickly build to 8-11 ft early on Mon while a plume of 8 ft seas will propagate downstream of the Gulf later in the day. Winds are expected to diminish to 25- 30 kt by late Monday morning and then remain a strong narrow plume of northerly winds through Wed morning before ending this event. 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 further details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from the coast of Costa Rica near 08N82W to 05N92W. The ITCZ continues from 05N92W to 06N98W to beyond 03N140W. A second southern hemispheric ITCZ extends from 03.4S93W to 02.5S101W to beyond 03.4S120W. Scattered moderate to strong convection is noted within 30 nm N and 180 nm S of the trough between 83W and 90W, within 90 nm either side of the northern ITCZ between 123W and 133W, and from 07.5N to 10N between 130W and 137W. Scattered strong convection is noted from 01.5S to 05S between 99W and 109W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A broad surface ridge extends through 30N126W to near the Islas Revillagigedo. The pressure gradient between this ridge and lower pressure over Mexico is producing moderate to fresh NW to N winds across the offshore waters off Baja California roughly north of 23N based on overnight scatterometer data. Seas are generally 7-9 ft across this region in NW swell. Winds and seas will decrease gradually through Mon night as the ridge weakens and shifts slightly SW. Fresh to strong winds are expected to return to the regional waters by Friday and a new ridge builds into the region. Gulf of California: Moderate to locally fresh NW winds are likely occurring across most of the Gulf of California this morning. Seas peak in the 3-5 ft range over the southern half of the Gulf, with 2-4 ft further north. Looking ahead, expect diminishing winds with seas 3 ft or less beginning Mon night as the pressure gradient weakens considerably. Moderate to strong S to SW winds are expected across far northern portions of the Gulf Tue through Tue night as a new low pressure system moves across the desert SW of the U.S. Gulf of Tehuantepec: See the Special Features section above for more details on the gale warning in effect. Gales will diminish by Mon afternoon with gap winds pulsing to 25-30 kt at night through Tue night-Wed morning. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Overnight scatterometer data depicted moderate E winds across the Gulf of Papagayo. Fresh to strong winds will pulse across the Papagayo region during the overnight and early morning hours through early next week. Gulf of Panama: Gentle to moderate N to NE winds will prevail across the Gulf and downstream to 05N through Tue night. High pressure will build north of the area on Wed as winds freshen across the Gulf through Thu. Elsewhere, light to gentle winds will prevail through midweek, with fading cross hemispheric SW swell dominating area seas. REMAINDER OF THE AREA... A cold front just NW of the area will slowly shift eastward and move into the far NW waters early Mon morning. Winds behind the front will continue to generate long period NW swell that will produce 8-9 ft seas over the far NW waters. The front will gradually weaken as it moves across the far NW portion of the area through early next week. The pressure gradient between high pressure offshore of southern California and lower pressure near the ITCZ is producing moderate to locally fresh trade winds south of about 20N and west of 116W based on the latest overnight scatterometer data. A 0230 UTC altimeter pass showed peak seas to 11 ft over this region in mixed NW and E swell. Areal coverage of 8 ft seas will gradually decrease over this area during the next few days as winds diminish in response to high pressure weakening over the northern waters. $$ Stripling