000 AXPZ20 KNHC 162151 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2205 UTC Sun Jul 16 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Hurricane Fernanda is centered near 12.7N 128.4W at 2100 UTC or about 1220 nm WSW of the southern tip of Baja California, moving WNW at 10 kt. Estimated minimum central pressure is 957 mb. Maximum sustained winds are 110 kt with gusts to 135 kt. Numerous strong convection is within 60 nm in the W semicircle and 90 nm in the E semicircle. Scattered moderate and isolated strong convection is elsewhere within 300 nm in the NE semicircle and 120 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 1011 mb low pressure about 250 nm SW of Acapulco, Mexico is center near 14N103W, 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 08.5N TO 17N between 100W AND 106W. The low is forecast to move generally WNW during the next couple of days, and has a medium chance of tropical cyclone formation within the next 48 hours. ...TROPICAL WAVES... A tropical wave along 115W/116W moving W at 10 kt. Afternoon scatterometer data reveals that an elongated low pressure center of 1011 mb has formed at the surface near 12.5N115W. Very active convection persists with scattered moderate to strong from 09N TO 15.5N between 113W AND 118W. The low pressure area will shift WNW over the next few days and has the potential to become better organized. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N75W to 08N93W to low pressure near 14N103.5W to low pressure near 12.5N115W to 11N120W, where it breaks to the E of Hurricane Fernanda, then resumes from 11N130W to 08N139W. Scattered moderate to strong convection is from 05.5N to 10N between 80W and 98W, and from 120 nm N to 180 nm S of the trough between 106W and 112W and between 130W and 139W. ...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. The post-tropical remnant low of Eugene has finally dissipated, leaving a weak trough from 29N130.5W to 25.5N130W. 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