000 AXPZ20 KNHC 211520 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1520 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Overnight scatterometer data revealed strong gale force winds through the Gulf of Tehuantepec, with marginal gales well downstream to near 13N96W. Maximum seas were analyzed to around 20 ft in the Gulf this morning, and a plume of seas greater than 8 ft in northerly swell reached as far south as 07N98W. Strong high pressure across southern Mexico will maintain gales in the Tehuantepec region through tonight and into early Wed morning. Wind speeds will diminish by Wed afternoon as the ridge weakens over Mexico. Marine interests transiting across or in the vicinity of the Gulf of Tehuantepec through tonight should take necessary action to avoid hazardous marine conditions. 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 07N78W to 06N81W to 1010 mb low pressure near 08N86W to 04N94W to 04N102W. The ITCZ extends from 04N102W to 07N125W to 06N140W. Scattered moderate isolated strong convection is noted within 120 nm of low center, and within 90 nm of the ITCZ west of 135W. Scattered moderate convection is occurring from 07N to 12N between 121W and 124W. 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 near 23N116W this morning, with a surface ridge extending SE across the Baja California Sur waters. Gentle to moderate northerly winds prevail offshore between Cabo San Lazaro and Cabo Corrientes, as well as over the southern Gulf of California. Meanwhile, weakening low pressure is located roughly 120 nm west of Guadalupe Island. This low will enter the offshore waters west of Punta Eugenia today, then dissipate tonight. Moderate to fresh northerly winds will develop west of Baja California Wed into 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 Thu night as high pressure builds over the Great Basin region. Long period NW swell is moving into the Baja California Norte waters this morning, with seas expected to build to 8-10 ft north of Punta Eugenia tonight. The swell will propagate SE across the region and reach the Revillagigedo Islands Wed. Seas will gradually subside through Fri as the swell decays. Another round of long period NW swell will reach the Baja California waters late Fri and build seas to 8 ft or greater this weekend. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Scattered moderate isolated strong convection persists offshore of Costa Rica and western Panama this morning, associated with 1010 mb low pressure near 08N86W. Showers and thunderstorms will likely continue through tonight, as the weak surface low persists offshore and the upper-level environment remains conducive for convection due to the passage of a Kelvin wave. Strong trade winds in the SW Caribbean will continue to support strong to near gale force NE to E winds over and 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 will impact the Guatemala and El Salvador offshore waters through Wed, with seas 12 ft or greater continuing into tonight. REMAINDER OF THE AREA... Weak low pressure centered near 29N121W is associated with fresh winds in its NW semicircle, based on overnight scatterometer data. The low will continue weakening today as it moves east- northeast, then dissipate overnight south of Guadalupe Island. The presence of this low center has disrupted the subtropical ridge over the area, resulting in weaker trade winds in the deep tropics east of 125W. Farther west, a broad area of fresh to strong NE winds is noted north of 10N and west of 125W between the ITCZ and high pressure building across the far NW portion. These winds will likely continue for the next couple days as the subtropical ridge strengthens and low-level troughing persists north of the ITCZ roughly along 135W. Seas greater than 8 ft in NW swell will dominate the region west of 120W by tonight, with peak seas around 12-13 ft associated with the strongest winds. Looking ahead, another set of long period NW swell will reach the NW portion on Thu, then propagate SE across the high seas through the weekend while gradually decaying. The associated cold front will cross the far northern waters Sat and Sun. $$ Reinhart