000 AXPZ20 KNHC 171501 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1501 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 1200 UTC surface analysis and satellite imagery through 1430 UTC. ...SPECIAL FEATURES... Hurricane Fernanda is centered near 13.7N 130.9W at 17/1500 UTC or about 1316 nm WSW of the southern tip of Baja California or about 1434 nm E of Hilo, Hawaii moving WNW at 9 kt. Estimated minimum central pressure is 954 mb. Maximum sustained winds are 110 kt with gusts to 135 kt. Numerous moderate to strong convection is within 75 nm of the center, except within 120 nm in the NE quadrant. Scattered moderate and isolated strong convection is elsewhere within 180 nm of the center, except 90 nm in the SE quadrant, and also in an outer band between 120 nm and 270 nm in the SE quadrant. Fernanda is expected to gradual weaken over the next several days. Large swells will continue to expand and spread out ahead of Fernanda to the NW and W during the next few days, and are expected to reach the Hawaiian Islands early Wednesday. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 for more details. Tropical Depression Seven-E near 14.1N 105.1W at 17/1500 UTC or about 295 nm S of Manzanillo, Mexico moving W at 5 kt. Estimated minimum central pressure is 1007 mb. Maximum sustained winds are 30 kt with gusts to 40 kt. Scattered moderate to strong convection is within 180 nm in the SE semicircle, and also between 75 nm and 150 nm in the W quadrant. The depression is forecast to strengthen to a tropical storm by this evening with little strengthening thereafter through the next few days, with gradually weakening commencing by the end of the week. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP2/WTPZ22 for more details. An area of low pressure centered near 13.5N117W 1008 mb, or about 685 nm SW of the southern tip of the Baja California peninsula. Scattered moderate to strong convection is within 270 nm to 300 nm in the S and SW quadrants of the low. Fresh to strong winds and seas of 8 to 10 ft can be found within 180 nm in the SE semicircle of the low. The low will continue to move slowly to the W or WNW through midweek. The low has a medium chance for tropical cyclone development during the next 48 hours. ...TROPICAL WAVES... The southern tip of a tropical wave reaches from the NW Caribbean Sea to across the Panama/Costa Rica border into the NE Pacific near 05N83W, moving W near 15 kt. Associated convection is described in the next section. A tropical wave reaches from the SW Gulf of Mexico across Mexico just W of the Gulf of Tehuantepec to 08N96W, moving W near 10 to 15 kt. Associated convection is described in the next section. A tropical wave reaches from near Cabo Corrientes to Tropical Depression Seven-E to 09N106W. Scattered moderate convection is from 17N to 24N between 105W and 108W near the northern portion of the wave axis. Additional associated convection and conditions with Tropical Depression Seven-E can be found in the Special Features section. A tropical wave reaches from 22N116W to low pressure near 13.5N117W to 08N117W. Associated convection and conditions are described in the Special Features section. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 09N75W to 10N97W to Tropical Depression Seven-E to low pressure near 13.5N117W to 13N123W, where it breaks to the east of Hurricane Fernanda, then resumes from 10N133W to 07N140W. No intertropical convergence zone axis is E of 140W. Scattered moderate and isolated strong convection is from 06N to 10N between 82W and 85W, from 06N to 10N between 86W and 92W, and also from 06N to 12N between 95W and 99W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the special features for information on Tropical Depression Seven-E SW of Acapulco, Mexico. A surface trough from the coast of southern California southward to off the coast of the Baja California peninsula will continue to 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 Tropical Depression Seven-E which is forecast to pass by to the SW-W of the region by 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 midweek 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. High pressure of 1032 mb well NW of the area near 38N159W extends a ridge E to SE through 32N140W to 22N130W. This is producing moderate to fresh N to NE winds across NW portions of the discussion area. The ridge will build modestly 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 to 9 ft through midweek. Swells generated by Fernanda will also 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, 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. $$ Lewitsky