000 AXPZ20 KNHC 181550 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Tue Jul 18 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 15.6N 133.3W at 1500 UTC moving NW at 8 kt. Estimated minimum central pressure is 974 mb. Maximum sustained winds are 85 kt with gusts to 105 kt. Numerous moderate to strong convection is within 90 nm of the center, and scattered moderate to strong convection elsewhere within 240 nm east and 150 nm west of the center. It is slowly weakening, and no longer exhibits a clearly defined eye. The weakening trend will continue over the next several days as it moves into the central Pacific. Large swell 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 Storm Greg is centered near 15.0N 108.3W at 1500 UTC or about 330 nm SW of Manzanillo, Mexico moving WNW at 8 kt. Estimated minimum central pressure is 1007 mb. Maximum sustained winds are 35 kt with gusts to 45 kt. Scattered moderate to strong convection is within 45 nm northwest and 90 nm southeast of the center. Some intensification is anticipated over the next couple days, with gradual weakening expected by the end of the week. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP2/WTPZ22 for more details. Newly formed Tropical Depression Eight-E is centered near 14.6N 118.8W at 1500 UTC, moving W at 4 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 45 nm north and 90 nm south of the center. Persistent weak northerly shear will inhibit much strengthening beyond minimal tropical storm intensity. The depression will move slowly west or west-southwest through midweek, and may interact with Tropical Storm Greg. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP3/WTPZ23 for more details. ...TROPICAL WAVES... A tropical wave extending north of 10N along 91W into Guatemala is moving west at 15 kt. This wave is enhancing the convection associated with the monsoon trough along 10N/11N. Another tropical wave extends north of 10N along 101W, moving west at 15 kt. Scattered moderate convection is noted along the monsoon trough near the tropical wave from 08N to 10N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 10N86W to 11N92W to 09N104W, resumes west of TS Greg from 15N114W through TD Eight-E to 13N125W, then resumes south of Fernanda near 11N133W to 08N140W. Except as noted above, scattered moderate isolated strong convection is located within 45 nm N and 75 nm S of the trough axis between 89W and 102W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the special features for information on Tropical Storm Greg southwest of Manzanillo, Mexico. Moderate to fresh easterly winds will sweep over the Revillagigedo Islands north of Tropical Storm Greg as it passes south of the region through Wednesday. A surface trough from the coast of southern California southward to off the coast of the Baja California peninsula near 24N120W 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 Thursday. Seas will remain 5 to 7 ft in a mix of long period north and southwesterly swell. Gentle southerly flow will persist in 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, then fresh northerly gap winds will once again pulse to around 20 kt at night. Winds may 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 max seas to 8 ft. Gentle to moderate southerly winds are expected south of the monsoon trough axis. Long period cross-equatorial southerly swell and 6-7 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 region today and raise seas to 6-8 ft through Thu. REMAINDER OF THE AREA... Please see the special features section for information on Hurricane Fernanda and Tropical Depression Eight-E. Weak ridging is producing moderate to fresh north to northeast winds north of 25N. The ridge will build modestly eastward through mid-week, tightening the gradient north of Fernanda as it moves west of 135W, and produce fresh northeast winds across much of the area north of 25N, helping build seas to 8-9 ft in mixed northerly and southerly swell. $$ Mundell