000 AXPZ20 KNHC 102121 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2121 UTC Sun Mar 10 2019 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. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough reaches from 9,5N85.5W to 06N95W. The intertropical convergence zone continues from 06N95W to 00N135W. No significant shower or thunderstorm activity is observed. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Weakening 1017 mb high pressure centered off the Baja California coast near 26N118W is maintaining gentle to moderate breezes and 4 to 6 ft seas in NW swell over open waters. Light to gentle breezes and 3 to 5 ft seas in NW swell are also noted elsewhere over Mexican offshore waters. A broad mid/upper level trough with an attendant cold front at the surface are approaching the area from the west. For the forecast, low pressure starting to develop along the cold front west of Guadalupe Island will move across the offshore waters of Baja California and the northern Gulf of California late tonight through Tue, with its associated cold front moving through the region and dissipating south of the Gulf of California through Tue. Scattered thunderstorms are likely off Baja California Norte Mon as the low pressure moves through the region. Strong winds will follow the low pressure off Baja California Norte through Tue. There is some hint in the GFS global model of minimal gales off Baja California Norte late Mon as well associated with the low pressure, but this is likely convective feedback, and is not observed in other operational models or ensemble wind spreed probabilities. Large, long period NW swell will also follow the front over open waters, reaching the Revillagigedo Islands by mid week, presenting hazardous surface conditions along the Baja California coast. Looking ahead, high pressure building over the Great Basin will support strong winds across the Gulf of California by late Thu. Farther south, a cold front moving through the western Gulf of Mexico will possibly bring gale-force gap winds to the Gulf of Tehuantepec by late Fri, persisting through Sat. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... A scatterometer satellite pass from around 16 UTC indicated fresh to strong easterly gap winds emerging out of the Gulf of Papagayo and southern Nicaragua, reaching around 300 nm into the Pacific. A nearly concurrent altimeter pass indicated seas to 8 ft within this plume. Farther east, recent ship observations indicated fresh gap winds into the Gulf of Panama. The gap winds are due to a moderately tight pressure gradient persisting across Central America. Little change is expected for the forecast, with fresh to near gale force NE winds prevailing across the Gulf of Papagayo and a few hundred miles downstream into the Pacific Ocean through Thu. Winds will be strongest during the overnight and early morning hours with the assistance of the nocturnal drainage flow. Fresh to locally strong N to NE gap winds will also pulse through the Gulf of Panama mainly at night through Wed morning. Gentle to moderate winds with a broad mix of swell will persist elsewhere. REMAINDER OF THE AREA... A cold front reaching from 30N120W to 22N130W will continue to sweep east of the area toward Baja California. Recent scatterometer and altimeter satellite passes confirm fresh to strong northerly winds and large seas, in the form of NW swell, following in the wake of the cold front over the waters north of 20N and west of 130W. The altimeter passes show seas as high as 17 ft near 30N136W. For the forecast, high pressure will build across the waters north of 20N in the wake of the front, allowing winds north of 20N to diminish late Mon into Tue. The large NW swell gradually decay as it moves through the region, but seas of 8 to 11 ft will dominate the waters west of 110W going into mid week. The ridge north of 20N will support a broad area of fresh to strong trade winds farther south into the tropics, with seas in that area a mix of NW swell and shorter period NE wind waves by mid week. $$ Christensen