000 AXPZ20 KNHC 151516 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1516 UTC Sat Jul 15 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 1200 UTC surface analysis and satellite imagery through 1500 UTC. ...SPECIAL FEATURES... Hurricane Fernanda is centered near 11.0N 123.0W at 15/1500 UTC or about 1034 nm SW of the southern tip of Baja California, moving W at 11 kt. Estimated minimum central pressure is 952 mb. Maximum sustained winds are 120 kt with gusts to 145 kt. Numerous moderate to strong convection is within 60 nm of the center. Scattered moderate isolated strong convection is occurring elsewhere within 270 nm in the NE semicircle and within 90 nm in the SW semicircle. Fernanda has weakened slightly due to eyewall replacement cycles, but is forecast to strengthen during the next 24 hours or so before gradually weakening thereafter. A gradual turn toward the W-NW is expected later today, and this motion should continue through Sunday, with large swells spreading and expanding out ahead of Fernanda to the NW and W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 for more details. A broad area of low pressure is SW-W of the Gulf of Tehuantepec area near 14.5N99.5W at 1012 mb along a tropical wave N of 08N, moving W at 10 kt. Deep convection has formed during the past several hours, with scattered moderate to strong convection within 180 nm in the SE semicircle. The low is forecast to move generally W-NW during the next couple of days and has a medium chance of tropical cyclone formation. ...TROPICAL WAVES... A tropical wave extends N of 08N along 99W/100W. Please refer to the Special Features section for more details on the tropical wave with regards to broad low pressure developing along the axis. A tropical wave from 06N to 16N along 110W/111W is moving W at 15 kt. The tropical wave is becoming less defined as it interacts with the outer circulation of Hurricane Fernanda which is located to the W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N75W to 08N83W to low pressure near 14.5N99.5W to 10N114W where it breaks approaching Hurricane Fernanda, then resumes from 10N128W to 08N136W. The intertropical convergence zone extends from 08N136W to 07N140W. Scattered moderate and isolated strong convection is from 06N to 11N between 112W and 116W. Scattered moderate convection from 06N to 09N between 124W and 129W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the special features for information on a broad area of low pressure SW-W of the Tehuantepec area. 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 northerly winds off the coast of Baja California peninsula, pulsing to 20 kt over the next couple of nights. Seas across these waters will remain 4 to 6 ft through early next 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 to fresh offshore winds this morning will diminish, then will pulse to moderate each night with nocturnal drainage through Tuesday morning, increasing back to fresh 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 and large set of southerly swell will move into the waters early next week. REMAINDER OF THE AREA... Please see the special features section for information on Hurricane Fernanda. The post-tropical remnant low of Eugene near 29.5N129.5W at 1017 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 will diminish later today. 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. $$ Lewitsky