000 AXPZ20 KNHC 100920 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Thu Aug 10 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 0600 UTC surface analysis and satellite imagery through 0830 UTC. ...TROPICAL WAVES... A tropical wave is along 85W/86W from Honduras southward, moving westward 10 to 15 knots. Convective precipitation was inland, from 09/1700 UTC until 09/2300 UTC, from Honduras to Nicaragua to Costa Rica. It eventually moved westward. It appears to be more concentrated around the 93W/94W tropical wave now. A tropical wave is along 93W/94W from 15N southward, moving westward 10 to 15 knots. Convective precipitation: scattered moderate to isolated strong from 05N to 14N between 88W and 95W. The interaction of energy that is associated with this tropical wave and the monsoon trough are forecast to develop gradually a broad cyclonic gyre in the far eastern part of the area, to the SW of Central America, by the end of the week and into the upcoming weekend. .INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from a 1010 mb low pressure center that is near 15N106W, to a 1013 mb low pressure center that is near 10N125W, beyond 12N140W. Convective precipitation: scattered moderate to isolated strong within 120 NM to the north of the monsoon trough from 123W westward, and within 270 NM to the south of the monsoon trough between 113W and 138W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... A surface ridge that is to the west of the Baja California peninsula and a broad surface trough that is along the Baja California peninsula are supporting moderate NE flow across the waters W of 110W, along with 4 to 5 ft seas. Mainly light to moderate onshore winds prevail elsewhere outside of the Gulf of California. Gentle to occasionally moderate southerly winds and seas of 2 ft or less prevail in the Gulf of California, except 3 to 4 ft near the entrance. Winds will become northerly in the southern Gulf by the end of the week. Global models develop an area of initially weak low pressure within 60 nm of the coast of Mexico from 17N to 20N a few hours after sunrise on Friday morning. Expect SE winds 20 to 25 knots and sea heights from 7 to 8 feet. The wind speeds are forecast to increase to SE 20 to 30 knots from noon on Friday until midnight or so on Saturday, and spread northwestward, from 19N to 22N within 210 nm of the coast of Mexico. The sea heights are forecast to range from 8 feet to 9 feet. Uncertainty remains with regard to the strength and impacts of any associated marine conditions. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Moderate southerly winds are expected S of the monsoon trough, with gentle and variable winds N of the monsoon trough. Seas are expected to be in the range of 4 to 6 ft. Long period southerly swell reaching the coastal areas of Costa Rica and Panama will decay through the end of the week. A new and extensive set of cross-equatorial swell is forecast by wave model guidance to cross 03.4S from 120W eastward, on Friday afternoon. This swell is forecast to reach the coastal waters of Panama and Costa Rica between 80W and 88W early on Sunday morning, and then cover the area that ranges from El Salvador to the western part of the Isthmus of Tehuantepec of southern Mexico, by sunrise on Monday. The sea heights will range from 7 feet to 10 feet across these offshore waters, except in the lee of the Galapagos Islands. REMAINDER OF THE AREA... A 1010 mb low pressure center is near 15N106W. Convective precipitation: scattered moderate to isolated strong from 17N to 24N between 104W and 109W, from 210 nm to 420 nm to the north of and away from the 1010 mb low pressure center. This low pressure center is expected to weaken and dissipate during the next 24 hours. A weak and broad ridge dominates the waters N of the convergence zone. Moderate trades and seas of 4 to 6 ft prevail N of the convergence zone under the ridging, with moderate to fresh southerly flow and 4 to 7 ft seas S of the convergence zone. Little overall change in these marine conditions is expected into the upcoming weekend. $$ mt