000 AXPZ20 KNHC 201520 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1520 UTC Mon Jan 20 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: A high pressure ridge across the eastern slopes of the Sierra Madre Mountains is maintaining a tight pressure gradient over southern Mexico. Gale force winds persist over and downstream of the Gulf of Tehuantepec this morning, with seas peaking around 18 ft. Strong gales to 45 kt will prevail in the Gulf later this afternoon and tonight as seas build to greater than 20 ft. Swell generated from this event will produce a plume of 8 ft or greater seas that will encompass much of the waters north of 03N and east of 105W by Tue night. Marine interests transiting across or in the vicinity of the Gulf of Tehuantepec today through Tue night should take necessary action to avoid these hazardous marine conditions. Gales will continue through early Wed morning, then quickly diminish by Wed afternoon as the ridge weakens over eastern Mexico. 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 this Gale Warning. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from near 06N77W to 04N97W to 06N104W. The ITCZ begins near 06N104W and continues to 08N123W to beyond 08N140W. Scattered moderate isolated strong convection is noted within 120 nm of the trough east of 90W, and from 06N to 09N between 125W and 133W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features above for more information on a strong gale force gap wind event in the Gulf of Tehuantepec. Weak high pressure is centered over the Baja California offshore waters this morning. Light to gentle northerlies prevail offshore of the Baja peninsula, with moderate NW winds over the central and southern Gulf of California and locally fresh winds near Cabo Corrientes. Outside of the Tehuantepec region, seas remain less than 8 ft throughout the forecast waters. A set of long period NW swell will reach the Baja California Norte waters on Tue, building seas to 10-11 ft. This swell will propagate SE across the region and reach the Revillagigedo Islands by Wed night. Seas will gradually subside through late week as the swell decays. Moderate to locally fresh northerly winds will develop offshore of Baja California Wed and Thu as high pressure builds NW of the region. Elsewhere, expect moderate to locally fresh NW winds across the central and southern Gulf of California Wed night through Fri as high pressure builds over the Great Basin region. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... The latest GOES-16 satellite imagery and lightning data show scattered moderate isolated strong convection near a surface trough that extends across the offshore waters roughly along 05N. The passage of a Kelvin wave over this region is creating upper- level conditions that are conducive for enhanced convection, which will likely continue through Tue night. Strong trade winds across the SW Caribbean will continue to support strong to near gale force NE to E winds across and downstream of the Papagayo region through Thu morning. Winds will be strongest during the overnight and early morning hours with the assistance of the nocturnal drainage flow. Seas will build to 10 ft each morning during the period of peak winds. Elsewhere, moderate to fresh northerly winds will persist in the Gulf of Panama region this week. Swell generated by the strong Tehuantepec gale event will spread into the Guatemala and El Salvador offshore waters through Wed, with seas greater than 12 ft expected today through Tue night. REMAINDER OF THE AREA... A 1009 mb low pressure center analyzed near 27N130W is likely still associated with fresh to strong winds based on overnight scatterometer data. Altimeter data from earlier this morning indicated seas up to 12 ft with this feature. This low will gradually weaken through Tue while moving east-northeastward, then dissipate early Wed just west of the Baja offshore waters. As the low moves eastward, the subtropical ridge will build into the NW portion. A developing low pressure trough north of the ITCZ near 135W will support strengthening NE winds and building seas west of 130W through midweek, as the gradient tightens between the trough and the subtropical ridge. A new set of long period NW swell entering the NW waters this morning will propagate SE across the high seas for the next several days. Seas will peak around 15 ft near 30N140W today, and seas greater than 8 ft will dominate west of 120W by Tue night. $$ Reinhart