000 AXPZ20 KNHC 090252 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sat Dec 9 2017 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 0000 UTC surface analysis and satellite imagery through 0300 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Storm Warning... NWP model data and upstream surface observations suggest gale force winds have begun within 60 to 90 nm of the Gulf of Tehuantepec. These winds will further increase to 40-45 kt by Sat morning, and to storm force 50-55 kt overnight Sat persisting into late Sun with seas building to 21-22 ft within the area of storm force winds. Gale force winds are likely to continue well into next week, producing a very large area of high seas well downstream from the source region. Gulf of Papagayo Gale Warning... Strong high pressure building north of the area behind a cold front entering the NW Caribbean late tonight will induce a strong gap wind event across the Gulf of Papagayo Sat night into early Sun morning when winds are forecast to reach minimal gale force. Mainly northerly winds are expected with this event reaching as far south as 07N88W on Sun. Seas are forecast to build to 10 or 11 ft downstream. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N85W to 07N100W to 08N117W. The ITCZ axis continues from 08N117W to 11N130W to beyond 09N140W. Scattered moderate convection is noted within 240 nm north of the ITCZ between 120W and 130W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Please, see Special Features section above. Intense high pressure north of the area over the Great Basin is supporting a tight pressure gradient over Baja California and northwest Mexico, with earlier scatterometer passes indicated strong winds. NWP models suggest the winds have subsided to 20-25 KT and are mainly to the S of 28N with seas only to 9 ft. The winds are forecast to drop below 20 kt by 24 hours. Fresh to strong NE winds are funneling through low-lying areas across the Baja California peninsula into the EPAC waters. Earlier scatterometer data provided observations of NE winds in the 20-30 kt range within about 120 nm off the coast of Baja N of 25N, including the Bay of Sebastian Vizcaino. These winds have subsided to 20-25 kt. Winds will diminish by early Saturday morning, with seas subsiding below 8 ft off the coast of Baja California through late Sat. Elsewhere gentle to moderate winds and 4 to 6 ft seas will persist through next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Please, see Special Features section above. Elsewhere, light to gentle N to NE winds are expected N of the monsoon trough, and mainly gentle to moderate S to SW winds are expected S of the trough. Seas are 4-7 ft in SW swell S of the monsoon trough. Large NW swell with wave heights of 8-10 ft from the upcoming Tehuantepec gap wind event will spread across the offshore waters of Guatemala this weekend. Localized gap wind pulses of 20 to 25 kt are possible off the coast of El Salvador and Guatemala, including the Gulf of Fonseca, starting Sat night. REMAINDER OF THE AREA... Long period NW swell continues to propagate across the forecast waters covering roughly the area north of 10N and west of 125W. The long period NW swell will mix with shorter period NE swell and wind waves originating from gap winds in Baja California tonight. The next cold front will approach the area on Sun with S to SW winds increasing to 20 kt. The front will extend from 30N137W to 27N140W by late Sun with Seas of 12 to 16 ft building in behind the front. This is my last product issued from the National Hurricane Center. It has been an honor and privilege to serve in the National Weather Service for the past 33.5 years. $$ Cobb