000 AXPZ20 KNHC 172105 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sun Mar 17 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A ridge across the eastern slopes of the Sierra Madre mountains in Mexico will continue to support minimal gale force winds in the Gulf of Tehuantepec through Thu morning. Brief lulls below gale force are likely during each afternoon. Large seas up to 12-14 ft will build during the strongest winds, with resultant NE swell propagating well downstream away from the source region to near 100W through Tue night. Northerly winds will then pulse to fresh to strong, mainly at night thereafter. Gale Warning: A strong cold front will reach the NW part of the discussion area later today. Associated NW swell has already moved east of 140W, and fresh to strong southerly winds are already affecting the NW corner of the forecast area. Gale force winds are expected ahead of the front this evening through early Mon, particularly N of 28N. NW swell will build to 17 ft behind the front by Mon evening, then continue to propagate across the waters W of 120W through early Wed morning while gradually subsiding. 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 trough extends from the coast of Colombia near 05N77W to 04N91W. The ITCZ continues from 04N91W to 02N110W to 04N127W to 03N140W. At this time, no significant convection is noted directly with the trough or ITCZ. A second and very active ITCZ is analyzed S of 03.4S. Scattered moderate convection is within 120 nm N of a line from 09N118W to 07N124W due to a mid to upper level trough. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please read the Special Features section for more details about the Gale Warning in the Gulf of Tehuantepec. Gulf of California: A weak pressure pattern will prevail through Tue with light variable winds, and seas generally 2 ft or less. A decaying front will approach the northern Gulf Tue night, producing S to SW winds in the 15 to 20 kt range through Wed night, with seas building to 4 to 6 ft. Gentle to moderate NW winds off Baja California peninsula will persist through Tue night, increasing to moderate to locally fresh Wed night through Thu night N of Cabo San Lazaro. During this time frame, NW swell associated with a decaying front will build seas to 8-11 ft. This swell event will reach the Revillagigedo Islands on Thu, with seas of around 8 ft. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: High pres across Central America will continue to support strong to near gale force winds in the Gulf of Papagayo through Mon, with fresh to strong winds thereafter. Winds will be greatest during the overnight and early morning hours with the assistance of the nocturnal drainage flow. Seas will build to 9-11 ft during the strongest winds. Gulf of Panama: Mainly fresh northerly winds will prevail in the Gulf of Panama at night, with the exception of fresh to strong winds tonight, and again on Fri night. Elsewhere, mainly gentle to moderate NE to E winds and 3-5 ft seas will prevail the next several days, except for 5-7 ft SW swell which will affect the waters between Ecuador and the Galapagos Islands through the early part of the week. REMAINDER OF THE AREA... Please read the Special Features section for more details about the gale warning in the Open Pacific NW Waters. A broad ridge extends across the northern waters to just beyond the Revillagigedo Islands. The pressure gradient between the ridge and the ITCZ supports moderate to occasionally fresh trade winds mainly S of 20N to the ITCZ. Altimeter data showed 6-8 ft seas across the region. Trades will gradually diminish over the next couple days as the ridge weakens. High pressure will build by the middle of the week in the wake of the aforementioned cold front, increasing trades S of 20N to the ITCZ, and allowing for seas to build to 8-11 ft combined with long period NW swell. Another cold front will approach 30N140W towards the end of the week with another large long period NW swell event. $$ Lewitsky