000 AXPZ20 KNHC 170250 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Mon Jul 17 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 0000 UTC surface analysis and satellite imagery through 0145 UTC. ...SPECIAL FEATURES... Hurricane Fernanda is centered near 13.0N 129.2W at 0300 UTC or about 1250 nm WSW of the southern tip of Baja California, moving WNW at 10 kt. Estimated minimum central pressure is 960 mb. Maximum sustained winds are 105 kt with gusts to 130 kt. Numerous strong convection is within 90 nm in the NE semicircle and 45 nm in the SW semicircle. Scattered moderate and isolated strong convection is elsewhere within 210 nm in the NE semicircle and 150 nm in the SW semicircle. Minor fluctuations in intensity are expected during the next 24 hours, then gradual weakening should commence for the remainder of the 5 day period. Large swells will spread and expand out ahead of Fernanda to the NW and W during the next few days, and are expected to reach the Hawaiian Islands early Tuesday. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 for more details. A broad area of 1010 mb low pressure about 285 nm SW of Acapulco, Mexico is center near 14N103.5W, and associated with a tropical moving W at 10 kt across the area. Associated winds on the NE side are fresh with seas to 7 ft in mixed southerly swell. Scattered moderate to strong convection is from 08N TO 15N between 101W AND 106W. The low is forecast to move generally WNW during the next couple of days, and has a high chance of tropical cyclone formation within the next 48 hours. A second area of 1010 mb low pressure is located near 12.5N115.5W, and associated with tropical wave along 116W moving W at 10 kt. Very active convection persists near the low with scattered moderate to strong from 09N TO 14.5N between 114.5W AND 118W. The low pressure area will shift WNW over the next few days and has a medium chance of tropical cyclone formation within the next 48 hours. ...TROPICAL WAVES... A tropical wave is crossing central America and entering the basin along 88W/89W moving W near 15 kt. The majority of associated convection is across interior portions of central America. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N75W to 07.5N94W to low pressure near 14N103.5W to low pressure near 12.5N115.5W to 11N120W, where it breaks to the E of Hurricane Fernanda, then resumes from 11N131W to 08N140W. Widely scattered moderate isolated strong convection is within 120 nm N and 180 nm S of the trough between 77W and 98W, and between 107W and 112W, and also from 06.5N to 11N between 130W and 140W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the special features for information on a broad area of low pressure SW of Acapulco, Mexico. A surface trough will develop tonight through Monday from the coast of southern California southward to off the coast of the Baja California peninsula. This will block the advance of the subtropical ridge into the region and maintain generally gentle to moderate winds off the Baja California peninsula through late week. Seas will still remain 5 to 7 ft however, in a mix of northerly and longer period S to SW swell. Farther S, moderate to fresh easterly winds will sweep across the Revillagigedo Islands on the N side of low pressure passing to the WSW of the region early to mid week. Gentle southerly flow will persist across the Gulf of California, except for moderate southerly flow over the northern Gulf. Light to gentle variable winds will prevail across the Gulf of Tehuantepec through mid week before fresh northerly gap winds pulse to strong at night. These winds will likely further increase to fresh to strong by the end of the week into next weekend. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, moderate to fresh offshore winds will pulse to fresh each night with nocturnal drainage through the week, occasionally building seas close to 8 ft. Gentle to moderate southerly winds are expected S of the monsoon trough axis. Long period cross-equatorial southerly swell and 6 to 7 ft seas will continue to propagate into the waters reaching the coast of Central America through the day. Another pulse of large southerly swell will move into the waters by Tuesday. REMAINDER OF THE AREA... Please see the special features section for information on Hurricane Fernanda. Strong high pressure is centered N of the Hawaiian Islands along 39N and extends a ridge E to near 39N140W then SE to 25N125W. This is producing moderate to fresh N to NE winds across NW portions of the discussion area. The ridge will build midestly eastward through mid week and tighten the pressure gradient to the N of Fernanda as it moves W of 135W to produce fresh to strong NE winds across much of the NW part of the area, where seas will build to 8-9 ft. Swells generated by Fernanda will propagate away from the center across tropical waters W of 120W the next several days. Northerly swell of 6 to 8 ft will propagate into the waters N of 25N and W of 120W starting Monday, mixing with southerly swell generated from Fernanda by Tuesday, with 7 to 9 ft combined seas. Elsewhere outside of the region within 360 nm of the path of Fernanda, winds will remain generally light to moderate with 5 to 7 ft seas. $$ Stripling