000 AXPZ20 KNHC 080915 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0900 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 propel a cold front into southern Mexico and Guatemala tonight, creating a very tight pressure gradients over Tehuantepec. Winds are expected to remain 20-25 kt through this evening, with gale force winds are expected to begin tonight. Winds will increase further 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. 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. The gale will persist through early afternoon today with 10-11 ft seas in areas with sufficient fetch. Strong winds will veer from NW to NE as high pressure over west Texas shifts SE. This will limit the fetch and allow seas to subside. The winds will diminish tonight as the pressure gradient weakens. Fresh to strong NW winds will persist in the northern Gulf Sat then diminish below 20 kt Sun. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N85W to 08N96W to 09N108W. The ITCZ extends from 10N112W to 11N125W to 08N140W. Scattered moderate to strong convection is noted within 120 nm of 09N110W. Scattered moderate convection is within 90 nm either side of the ITCZ axis between 119W and 134W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Strong NE winds will funnel through low-lying areas over Baja California Norte into the Bay of Sebastian Vizcaino, roughly between Santa Rosalita and Puerto Canoas today, with seas to 8-9 ft within 60 nm of the coast. 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 8-12 ft today. 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 into next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Gentle to moderate gap winds will occasionally pulse to fresh through tonight. Strong high pressure building north of the area behind a cold front penetrating into the NW Caribbean will induce strong gap winds Sat night, reaching near gale by Sun morning and again Mon morning with seas building to 11 ft downstream. 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. A stationary front extends from 30N135W to 23N137W. Associated long period NW swell has propagated into the region within an area roughly north of 10N and west of 130W. The long period NW swell will mix with shorter period NE swell and wind waves originating from gap winds in Baja California by early Sat in the area north of 20N and east of 125W. $$ Mundell