000 AXPZ20 KNHC 110206 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 206 UTC Mon Mar 11 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 0000 UTC surface analysis and satellite imagery through 0200 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... A surface trough reaches from 09N84W to 06N90W. The intertropical convergence zone continues from 06N90W to 00N135W. Scattered moderate shower and isolated thunderstorm activity is observed within 60 nm north of ITCZ between 115W and 122W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... 1015 mb high pressure centered off the Baja California coast near 26N118W is dissipating ahead the approach of a developing 1012 mb low west of the area near 27.5N126W, along with its associated cold front. Currently, gentle to moderate breezes are noted across Mexican offshore waters with and 4 to 6 ft in NW swell in open waters. For the forecast, the low pressure 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... An earlier scatterometer satellite pass 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, although a more recent altimeter pass indicated the seas have subsided, at least temporarily with relatively weaker afternoon gap winds. 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... 1012 mb low pressure is developing near 28.5N126W, along a cold front reaching to 20N130W. The low pressure and cold front are moving eastward toward Baja California. A recent scatterometer satellite pass and ship observations confirm strong northerly winds following in the wake of the cold front over the waters north of 20N and west of 130W. Concurrent altimeter passes along with ship observations are showing large 10 to 17 ft seas, with the highest 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 will 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