000 AXPZ20 KNHC 210900 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue Jan 21 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 0900 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Storm Warning: Strong high pressure across southern Mexico is supporting winds reaching at least 48 kt, based on scatterometer data, through the Gulf of Tehuantepec. Maximum seas are estimated to be 22 ft downstream of the Gulf of Tehuantepec, and a plume of swell in excess of 8 ft extending several hundred nm downstream, expected to encompass much of the waters north of 03N and east of 105W today. Marine interests transiting across or in the vicinity of the Gulf of Tehuantepec through today should take necessary action to avoid hazardous marine conditions. Gales will continue into Wed morning, then quickly diminish Wed afternoon as the ridge weakens over 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 Storm Warning. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough extends from near 06N77W to 07N87W to 05N100W. The ITCZ begins near 05N100W and continues to 07N118W to 06N140W. Scattered moderate isolated strong convection is noted from 04N to 10N between 80W and 87W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features above for more information on a storm force gap wind event in the Gulf of Tehuantepec. Weak high pressure centered near Guadalupe Island is maintaining light to gentle northerlies north of 17N, with moderate NW winds over the central and southern Gulf of California and near Cabo Corrientes. Outside of the Tehuantepec region, seas remain less than 8 ft throughout the forecast waters. Long period NW swell will reach the Baja California Norte waters today, building to 10-11 ft tonight. The swell will propagate SE across the region and reach the Revillagigedo Islands Wed night. Seas will gradually subside through Fri as the swell decays. Moderate northerly winds will develop west of Baja California Wed and Thu as high pressure builds NW of the region. Elsewhere, expect moderate to fresh NW winds over 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... A large area of showers and thunderstorms continues to be active off the coast of western Panama and Costa Rica. This activity is north of a surface trough extending east to west along roughly 05N. A Kelvin wave passing over this region is creating upper- level conditions that are conducive for enhanced convection, which will likely continue through tonight. Strong trade winds in the SW Caribbean will continue to support strong NE to E winds downstream of the Papagayo region through Thu morning. Winds will be strongest during overnight and early morning hours. 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 a strong Tehuantepec wind event is spreading into the Guatemala and El Salvador offshore waters through Wed, with seas greater than 12 ft expected there through tonight. REMAINDER OF THE AREA... A scatterometer pass from 0640 UTC indicated areas of fresh to strong winds north of an elongated low pressure area centered near 29N123W. The low will gradually weaken today and continue moving east-northeast, then dissipate early Wed near Guadalupe Island. The presence of this low center has disrupted the usual subtropical ridge over the area, resulting weaker trade winds in the deep tropics east of 130W, evidenced by scatterometer data and buoy observations. A mid-level disturbance interacting with trade wind convergence along the ITCZ between 120W and 125W supports scattered showers. Farther west, a surface trough has developed along the ITCZ near 135W in an area of deep layer moisture SE of a broad mid/upper level trough. This is a favorable area of further development. Fresh to strong NE winds could develop between the trough and high pressure building north of the area the next two days. Long period NW swell crossing 30N140W will propagate SE across the forecast waters for the next several days. Seas greater than 8 ft will dominate the region west of 120W by late tonight. Looking ahead, a cold front accompanied by more long-period NW swell will pass southwest of 140W by Sat. $$ Mundell