000 AXPZ20 KNHC 102120 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sat Dec 10 2016 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: Strong high pressure over southern and eastern Mexico is maintaining a tight pressure gradient over the Isthmus of Tehuantepec. This gradient is expected to support sustained winds to around 40 kt tonight, then the gradient will slacken Sunday as high pressure over the western Gulf of Mexico weakens and shifts eastward. Max seas will be 15-16 ft today, then subside below 8 ft Monday. North winds will pulse to near 25 kt overnight Monday and Tuesday. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N84W to 07N89W to 06N98W. The ITCZ continues from 06N98W to 09N109W to 09N125W to 08N140W. Scattered moderate isolated strong convection is within 60 nm either side of a line from 10N112W to 13N119W to 07N131W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface trough is analyzed along the eastern coast of the Gulf of California from 23N106W to 31N113W. High pressure centered near 28N128W extends a ridge eastward to Baja California along 27N, and ridging dominates the offshore waters. Aside from the Tehuantepec high wind event, light to gentle winds will prevail S of 17N through the forecast period. Fresh to locally strong NW winds north of 28N along the west coast of Baja California will continue through Sunday night, then diminish Monday as the ridge weakens in response to low pressure approaching from the NW. Between 17N and Mazatlan moderate to fresh northwest winds will prevail through Tuesday night. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Fresh to strong offshore winds east of 92W will continue to pulse mainly during the overnight hours this weekend. Max seas during this event will be 8-9 ft. An easterly wave over the western Caribbean will cross Central America early Monday. Some model guidance calls for low pressure development along the wave axis as it moves westward away from Costa Rica on Tuesday and Wednesday. Model guidance consensus and climatology both suggest this system will remain a trough or weak low during this time frame. Light to gentle north to northeast winds and combined seas of 3 to 5 ft are occurring north of the monsoon trough, which is expected to meander between 08N and 10N through Wednesday. Light to moderate southwest winds are observed from 05N to 09N, with combined seas hovering between 3 and 5 ft in southwest swell. Moderate to fresh southerly flow is expected south of 05N through Wednesday. REMAINDER OF THE AREA... High pressure centered near 28N128W ridges southeast to near 19N109W. Gentle to moderate north-northwest flow is expected northeast of the ridge axis this weekend and moderate to fresh trades will prevail south of the ridge axis, north of the ITCZ. Fresh to occasionally strong NE winds and combined seas of 8-9 ft will prevail from 07N to 15N W of 125W through Monday. Low pressure encroaching on the far northwest waters will weaken the ridge and maintain a relatively light wind regime in this area Tuesday through Friday. $$ Mundell