000 AXPZ20 KNHC 160245 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 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 0000 UTC surface analysis and satellite imagery through 0130 UTC. ...SPECIAL FEATURES... Hurricane Fernanda is centered near 11.7N 125.4W at 0300 UTC or about 1112 nm SW of the southern tip of Baja California, moving WNW at 12 kt. Estimated minimum central pressure is 957 mb. Maximum sustained winds are 110 kt with gusts to 135 kt. Numerous strong convection is within 75 nm NW and 45 nm SE semicircles. Scattered moderate isolated strong convection is occurring elsewhere within 240 nm in the NE semicircle and within 150 nm in the SW semicircle. Fernanda has weakened slightly due to an ongoing eyewall replacement cycle, but is forecast to strengthen again during the next 24 hours or so before gradually weakening thereafter. A gradual turn toward the W-NW has begun tonight, and this motion should continue through Monday. Large swells will spreading and expanding out ahead of Fernanda to the NW and W during the next few days and are expected to reach the Hawaiian Islands early Tue. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 for more details. An elongated area of low pressure is S through SW of Acapulco Mexico, with a likely developing low center near 14N101W at 1012 mb. This feature is associated with a tropical wave moving W at 10 kt across the area. Deep convection has persisted today, with scattered moderate to strong convection from 10N to 16N between 96W and 104W. The low is forecast to move generally W-NW 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 extends N of 08N along 101W. Please refer to the Special Features section above for more details on the tropical wave and the associated elongated low pressure developing along the wave. A tropical wave is S of 16N along 112W/113W is moving W at 15 kt. Although active convection continues between 110W and 119W, the tropical wave is becoming less defined as it interacts with the outer circulation of Hurricane Fernanda located to the W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N75W TO 08N83W TO developing low pres near 14N101W TO 10N116W where it breaks to the E of Hurricane Fernanda, then resumes from 09N128W TO 08N136W. The ITCZ extends from 08N136W to 07.5N140W. Scattered moderate to strong convection is occurring within 240 nm S of the trough between 87W and 95W, and from 07.5N to 13.5N between 110W and 119W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the special features for information on a broad area of low pressure S-W of Acapulco. The subtropical ridge continues to build in the wake of the rapidly weakening remnant low of Eugene well W of the region. This is allowing a tight enough pressure gradient to support moderate NW to N winds off the coast of Baja California peninsula, and will pulse to 20 kt over the next couple of late afternoons and evening. Seas across these waters will remain 4 to 5 ft through early Mon, before northerly swell invades the area and raises seas to 5-6 ft through mid week. Winds are expected to become light and variable again by early next week as broad troughing sets up across the offshore waters. Mainly light and variable winds and 1 to 3 ft seas will prevail in the Gulf of California, except 3 to 4 ft seas S of 23N towards the entrance to the Gulf. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... In the Gulf of Papagayo, moderate offshore winds will pulse to fresh each night with nocturnal drainage through Tuesday morning, increasing fresh to strong thereafter. Gentle to moderate southerly winds are expected south of the monsoon trough axis. Long period cross-equatorial southerly swell and 6 to 7 ft seas will continue to propagate into the waters W of Colombia and Ecuador, with a reinforcing pulse of swell moving into the area this morning, reaching the Central America coast Saturday night and Sunday. Another pulse of large southerly swell will move into the waters by Tue. REMAINDER OF THE AREA... Please see the special features section for information on Hurricane Fernanda. The post-tropical remnant low of Eugene near 29N130W at 1018 mb is drifting northwest and gradually dissipating, with no discernible deep convection. Moderate to fresh NE winds on the N side of the low pressure have diminished. Swell generated by Fernanda will propagate away from the center across tropical waters west of 120W the next several days. It is expected to cross 140W and move into the Central Pacific by early next week. Elsewhere outside of the region within 300 nm of the path of Fernanda, winds will remain generally light to moderate with 5 to 7 ft seas. $$ Stripling