000 AXPZ20 KNHC 271518 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1515 UTC Wed Mar 27 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 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Overnight scatterometer data confirmed gale force gap winds over the Gulf of Tehuantepec. Gale force winds are expected to persist through Thu morning as surface high pressure builds southward across the western Gulf of Mexico and into eastern Mexico behind a cold front. Wind speeds will diminish slightly today, then strengthen again to 40 kt later tonight. Seas peaked around 18 ft this morning with associated swell generating a plume of 8-12 ft seas well downstream of the Gulf as revealed by 12Z altimeter data. 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 more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from the coast of Colombia near 05N77W to 06N86W. The ITCZ continues from 06N86W to 03N100W to 01N105W to 01N120W to beyond 05N140W. Scattered moderate convection is occurring within 60 nm of the ITCZ between 95W and 100W, within 90 nm north of the ITCZ between 118W and 123W, and within 120 nm north of the ITCZ west of 132W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Please refer to the Special Features section above for more information about the Gale Warning currently in effect. Gale force conditions are expected to diminish by Thu afternoon. Light to gentle winds will prevail over the weekend as high pressure moves eastward away from the region. Gulf of California: Relatively tranquil conditions will prevail through the weekend with winds generally less than 15 kt and seas 4 ft or less. Northwest winds over the central and southern Gulf may reach fresh speeds Fri night as high pressure briefly builds over the Great Basin. Elsewhere, weakening surface high pressure is centered west of Baja California Norte with moderate NW winds over the adjacent offshore waters. Stronger high pressure will build toward the region on Thu behind a weakening cold front. This will enhance the offshore pressure gradient and support fresh to strong NW to N winds off the Baja Peninsula through Fri night. Seas will build to 10 ft by Thu night over the waters north of Punta Eugenia. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Strong to near gale force NE to E winds will continue pulsing in the Gulf of Papagayo through Fri. The strongest winds each day will occur during the late night and early morning hours as nocturnal drainage flow enhances wind speeds. Seas were analyzed to 11 ft this morning downstream of the Gulf in mixed SW swell and NE wind waves. Looking ahead, wind speeds will generally diminish to fresh speeds this weekend. Gulf of Panama: Fresh to strong N to NE winds in the Gulf of Panama will persist through tonight as surface high pressure builds into the Caribbean Sea. These winds will diminish to moderate to fresh speeds Thu through Sun. A combination of NE wind waves and cross-equatorial SW swell will produce seas to 8 ft downstream from Panama through Fri. Elsewhere, satellite analysis revealed a large area of light to moderate smoke impacting the offshore waters off Guatemala and El Salvador this morning. Further south, southern hemisphere swell will continue to impact the offshore waters between Ecuador and the Galapagos Islands through Fri. Expect seas to 8 ft as longer period SW swell mixes with shorter period NE swell downstream from the Gulf of Panama. REMAINDER OF THE AREA... A surface trough extends from 30N125W to 25N132W this morning, while a cold front is over the far northern waters from 30N128W to 27N133W. NW swell associated with these features has produced an area of 8-11 ft seas over the NW portion roughly north of 24N west of 130W. Another cold front expected to stall just NW of the forecast area on Fri will introduce another set of long period NW swell that will propagate SE across the high seas beginning Thu. Overnight scatterometer data showed moderate to fresh NE to E trade winds roughly from 04N to 12N W of 110W. Seas in this region were generally 8-10 ft according to several recent altimeter passes. The trade winds will strengthen on Thu and persist through Fri night as strong surface high pressure builds north of 30N. Further east, a combination of longer period NW and SW swell with shorter period NE swell is maintaining an area of 8-10 ft seas generally south of 15N between 95W and 110W. Similar wave heights will persist into Fri as gap winds in the Gulf of Tehuantepec and Gulf of Papagayo continue generating fresh swell plumes. Seas will subside by this weekend as gap wind speeds diminish and the residual swell gradually decays across the area. $$ Reinhart