000 AXPZ20 KNHC 221518 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1518 UTC Thu Jun 22 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. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N86W to 1008 mb low pressure near 14N95W to 06N135W. The intertropical convergence zone axis extends from 06N135W to beyond 06N140W. Scattered moderate and isolated strong convection is from 04N to 12N between 77W and 87W, from 07N to 14N between 94W and 98W, and within 60 nm either side of monsoon trough axis between 105W and 120W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface trough remains in place from 27N115W near Cabo Eugenia to 1009 mb low pressure near 23N118W to 16N125W. This is breaking up the usual subtropical ridge in the area, maintaining a fairly light pressure pattern and subsequent wind pattern off the Baja California peninsula, where various ship observations confirm light to gentle breezes. Recent altimeter satellite passes indicated long period northwest swell with wave height reaching 8 to 10 ft persist over the waters beyond 120 off the coast off the Baja California peninsula as far south as 25N, with 5 to 7 ft closer to shore. The swell will decay below 8 ft through early Friday. The trough will dissipate through late Friday, allowing the ridge to build eastward. This will support moderate to occasionally fresh northwest winds along the Baja coast through Sunday with 5 to 7 ft seas. Looking ahead, the pattern will repeat as weak troughing develops off the Baja coast allowing winds to diminish slightly early next week. Recent scatterometer also indicates gentle to moderate southerly flow across the Gulf of California between the trough and weak ridging off Cabo Corrientes. Locally fresh winds are possible near Los Cabos and over the northern Gulf of California later today, but otherwise moderate breezes and slight seas will persist through early next week. Farther south, 1008 mb low pressure centered near 14N95W will continue to move slowly to the west-northwest over the next couple of days. In addition to supporting scattered showers and thunderstorms in its vicinity, the low pressure will enhance east to southeast winds off the coasts of Chiapas and Oaxaca through Saturday with seas building to 7 ft. The current forecast is for the low to gradually weaken thereafter as it drifts northwestward along the Mexican coast toward Cabo Corrientes through early next week. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gentle to moderate southwest to west winds are expected across most of the forecast area during the forecast period, with the exception of mainly south winds between Ecuador and the Galapagos Islands, as the pressure gradient remains weak. Long period southwest swell of 5 to 7 ft will gradually decay through the upcoming weekend. REMAINDER OF THE AREA... A ridge dominates most of the waters north of the convergence zone. Scatterometer and altimeter passes continue to indicate an area of moderate to fresh winds and seas of 8 to 10 ft roughly north of 20N and W of 120W. The ridge will shift west as a weak low near 23N118W with an attendant trough drift west. The low and troughing will continue to drift southwest to west before dissipating Saturday. Northerly swell will continue to propagate across the waters N of 20N, building to 10 to 12 ft N of 28N through Friday, as fresh swell moves in around a low pressure system N of the area. Seas will decay through the upcoming weekend as the low moves NW while weakening. $$ Christensen