000 AXPZ20 KNHC 081546 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Fri Dec 8 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Storm Warning... N to NE winds of 20-25 kt are funneling into Tehuantepec with maximum wave heights just below 8 ft, as a frontal system stalls over the western Gulf of Mexico. A push of cold air and strong high pressure will allow the cold front to reach the Yucatan Peninsula and Guatemala tonight, creating a very tight pressure gradient over the western Gulf of Mexico and the Tehuantepec region. Winds are expected to increase to 30 kt through this evening, with gale force winds beginning tonight. Winds will further increase to 40-45 kt by late Sat, and to storm force 50-55 kt by early Sun, and persist through early Mon. But gale force winds are likely to continue well into next week, producing a very large area of high seas downstream from the source region. Seas are expected to build to 21 or 22 ft within the area of storm force winds. Gulf of California Gale Warning... Intense high pressure north of the area over the Great Basin is supporting a tight gradient over Baja California and northwest Mexico, and producing minimal gale force winds over the Gulf of California based on scatterometer data. A recent altimeter pass indicated seas up to 12 ft within the area of gale force winds. The gale will persist through early this afternoon. Fresh to strong winds will persist across the gulf through tonight, with seas gradually subsiding to 8 ft. 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 11N124W to 10N138W. The ITCZ axis continues from 10N138W to beyond 09N140W. Scattered moderate convection is noted within about 120 nm S of trough between 104W and 110W. Similar convection is from 08N to 14N between 120W and 130W, and from 07N to 10N between 130W and 134W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Gulf of Tehuantepec: Please, see Special Features section above. Strong NE winds are funneling through low-lying areas across the Baja California peninsula into the EPAC waters. The most recent 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. The main short-term issue for the rest of Baja California will be strong NE winds south of 30N, reaching nearly 400 nm into the Pacific open waters with seas of 8-11 ft today. Winds will diminish by early Saturday morning, with seas subsiding below 8 ft off the coast of Baja California through late Sat. Fresh to strong winds across the Gulf of California are also spreading beyond the entrance of the gulf affecting the waters from 20N to 23N between 107W and 109W with seas to 8 ft. 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... The stationary front located over the NW waters has dissipated, and a trough is analyzed on the 1200 UTC map extending from 30N136W to 25N140W. 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 later today. by early Sat in the area north of 20N and east of 125W. $$ GR