000 AXPZ20 KNHC 190915 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 915 UTC Sat May 19 2018 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 1030 UTC. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N86W to 10N125W to a 1010 mb low pressure area centered 08N131W. The intertropical convergence zone continues from there to beyond 06N140W. Scattered moderate to isolated strong convection is from 06N to 10N east of 105W. Scattered moderate convection is ongoing from 10N to 12N between 115W and 125W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Moderate to fresh NW winds are noted in a 05 UTC scatterometer pass off the coast of Baja California. Concurrent altimeter satellite passes showed seas generally 5 to 7 ft. Generally light westerly winds are noted over the Gulf of California, with slightly stronger westerly gap winds near low level areas over the peninsula. Light westerly winds are noted farther south off the Mexican coast. The main forecast issue ahead will be the onset of long period SW swell in excess of 8 ft into the open Pacific waters off Mexico. The swell will reach waters of southern Mexico by early Mon, and into the open waters off Baja California Mon night and Tue, mixing with NW swell off Baja California Norte. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Gulf of Papagayo: Light to gentle winds will dominate the gulf the entire forecast period as weak pressure will prevail across Central America. Seas of 5-8 ft are forecast over the Gulf and nearby waters through mid week due to long period SW swell. Gulf of Panama: Gentle to moderate S to SW winds are forecast through Wed with seas of 4-6 ft in long period SW swell, building to 5-7 ft on Mon as the swell reaches the coasts of Panama and Colombia. Elsewhere, gentle to moderate SW winds are expected to the south of the monsoon trough with light to gentle variable winds north of trough as a weak pressure pattern remains over Central America. Seas of 6-7 ft in long period SW swell west of the Galapagos Islands are expected to propagate northward Sat through late Tue next week building to 9 ft Sat. REMAINDER OF THE AREA... A cold front is moving through the eastern Pacific and entering into the northwest corner of the discussion. The subtropical ridge remains weak as the front approaches the area, but it is strong enough to support moderate to locally fresh trade winds in the deep tropics. Seas are approaching 8 ft in pockets north of the monsoon trough/ITCZ in areas of fresh trade winds. The front will weaken as it shifts eastward today. The ridge will build eastward in the wake of the dissipating front, allowing the areal extent of the trade winds, and subsequently the areas of 8 ft seas to expand over the deep tropics. Meanwhile cross equatorial southerly swell continues to propagate into the region, with seas reaching 8 ft as far north as 10N between 95W and 125W early in the week. Various wave model guidance shows the large SW swell encompassing most of the region south of 20N and east of 120W by mid week. Meanwhile, weak 1010 mb low pressure along the monsoon trough near 130W will drift west through early next week. Fresh trade winds north of the low pressure may reach 20 to 25 kt with seas to 10 ft by early next week as the ridge to the north builds. No significant development is expected. $$ Christensen