000 AXPZ20 KNHC 180920 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Sat Jan 18 2020 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: High pressure over the Gulf of Mexico will maintain strong to minimal gale force N winds across the Tehuantepec region through Sun. Seas in excess of 8 ft reach several hundred miles downstream of the Gulf, mixing with longer period NW swell. Looking ahead, a cold front will move across the Gulf of Mexico Sun and Mon, and induce a stronger and much broader gale wind event across Tehuantepec Sun night through Tue night, then diminishing on Wed. Winds will peak around 40 kt, with seas between 16 and 17 ft. Winds will greatest during the overnight and early morning hours, when nocturnal drainage flow augments the winds. Papagayo region Gale Warning: A broad persistent ridge across the Caribbean and Central America is supporting strong to near gale force NE to E winds across and downstream of the Papagayo region, extending downstream more than 200 nm. Winds will pulse to minimal gale force this morning, and exceed 30 kt tonight. Seas will peak between 10 and 12 ft during this period of peak winds. Fresh to strong E to NE winds will prevail across the region Sun through Tue. Please see 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 on these two Gale Warnings. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from near 07N78W to 05N96W. The ITCZ continues from 05N96W to beyond 08N140W. No significant convection is observed. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see above for more on the latest gale force gap wind event in the Gulf of Tehuantepec. A surface ridge extends from high pressure off the coast of southern California near 34N123W to the Revillagigedo Islands. A mid-level trough is slowly moving eastward across the region north of 20N, and is passing across the Gulf of California. Latest ship observations and scatterometer data show moderate to fresh NW winds off the coast of Baja California and through the central Gulf of California. The high pressure off southern California along with strong high pressure building over the southern plains of the US will set up a tight pressure gradient in the Gulf of California, and support fresh to strong winds through tonight over the central Gulf of California. High pressure will shift southward Mon, supporting a pulse of fresh to strong winds near Cabo Corrientes. Looking ahead, a cold front will approach Baja California Norte and Guadalupe Island Tue and Tue night, accompanied by NW swell of 8- 10 ft, before stalling and dissipating Wed. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Please see above for more on the latest gale force gap wind event in the Papagayo region. The pressure gradient responsible for the gap winds in southern Mexico and Central America is also supporting fresh to strong NE to E winds across the waters of northern Nicaragua and offshore of the Gulf of Fonseca, as well as fresh northerly winds in the Gulf of Panama. Winds across the Gulf of Panama and downstream to near 04N will increase each night this week, with downstream seas building to 6-7 ft by sunrise. REMAINDER OF THE AREA... Latest scatterometer data and observations from TOGA buoys show a large area of fresh trade winds west of 115W between 10N and 18N. Recent altimeter passes continue to show seas of 8-10 ft, likely in mixed swell and NE to E wind waves. These winds have been diminishing as high pressure weakens ahead of a dissipating frontal boundary north of 28N. High pressure building behind the boundary will support a large area of fresh to locally strong trade winds south of 20N west of 120W today. Seas in this area will remain between 8 and 10 ft. Farther east, 8-9 ft seas persist between 06N-12N between 95W and 120W, due to swell originating from ongoing gap winds farther east in the Gulf of Tehuantepec and off the Nicaraguan coast. The synoptic pattern will change significantly early Sun, as a deep layer trough north of Hawaii shifts eastward. An associated surface low will drift eastward along roughly 25N, reaching 135W on Sun. Strong to near gale force southerly winds, with seas to 12 ft could occur within 360 nm southeast of the low center as it moves to the east-northeast. The low and associated weather is expected to move north of 30N late Mon, leaving a trailing trough toward 10N140W. Looking ahead, high pressure building along 25N in the wake of the exiting low pressure system may interact with the trough, to support fresh to strong NE winds between the ITCZ to around 20N west of 130W Tue and Wed. $$ Mundell