000 AXPZ20 KNHC 200316 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Wed Jul 20 2016 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... Tropical Storm Darby is centered near 20.0N 137.8W at 0300 UTC, which is about 1000 nm east of Hilo Hawaii. Darby is moving west or 280 deg at 11 kt. The maximum sustained winds remain 55 kt with gusts to 65 kt. The estimated minimum central pressure is 994 mb. Latest satellite imagery shows that the associated convection has increased slightly in coverage and intensity in the past 6 hours, with scattered moderate to strong convection within 45 nm across the nw semicircle, while scattered moderate convection was observed within 120 nm northwest and 30 nm southeast semicircle. Darby is forecast to gradually continue to weaken over the next 48 hours, when it will move west of 140W and out of the discussion area. Refer to the latest NHC forecast advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 KNHC for more details. Also, refer to the latest high seas forecast MIAHSFEP2/FZPN03 KNHC for more details on the wave forecasts associated to Darby. Tropical Storm Estelle is centered near 19.1N 121.0W at 0300 UTC, which is about 660 nm sw of the southern tip of the Baja California Peninsula at 0300 UTC. Estelle is moving west, or 280 degrees at 11 kt. The maximum sustained winds have increased slightly to 60 kt with gusts to 75 kt. The estimated minimum central pressure is 990 mb. Convection has improved across the western semicircle of Estelle during the past 6 hours and isfinally showing signs of intensification recently forecast by computer models. Scattered to numerous strong convection isobserved within 90 nm across the sw semicircle, while scattered moderate to strong convection is noted elsewhere within 120 nm of center. Estelle is forecast to strengthen to minimal hurricane strength overnight through Wednesday morning before weakening back to tropical storm strength later on Wednesday. A slow and gradual weakening trend is then expected beginning Thursday as Estelle continues west-northwestward. Refer to the latest NHC forecast advisory under AWIPS/WMO headers MIATCMEP1/WTPZ21 KNHC for more details. Also see latest high seas forecast MIAHSFEP2/FZPN03 KNHC for more details on the wave forecasts associated with Tropical Storm Estelle. ...TROPICAL WAVE... A tropical wave along about 92W and has been moving w at about 10 kt. Convection remains ahead of the wave to between 94w and 99w, and along the coastal waters of central America between 87Wand 93W. Fresh to strong northerly winds and blowing across and downwind of the Gulf of Tehuantepec in advance of this wave. ..INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from Colombia near at 09N76W to 08N85W to 10N102W to 09N109W to 12N116.5W, where it loses identity in broad cyclonic circulation associated with the southeast periphery of Tropical Storm Estelle. Scattered moderate isolated strong convection is noted within 210 nm S of trough E of 86W. Scattered moderate to strong convection noted within 300 nm N and 210 nm S of trough between 89W and 104W, and within 210 nm S of trough between 104W and 115W, and from 08N to 11N between 115W and 124W. ...DISCUSSION... N of 15N e of 120W: See special features section above for details on tropical cyclone Estelle which will continue westward across the sw portion of the discussion area, with the associated area of tropical storm conditions shifting w of 120W tonight, while the associated seas of 8 ft and greater will shift west of 120W Wed evening. A surface ridge will build east-southeast across northern portions of the area as Estelle and Darby continue moving westward. This new ridge will extend through 26N120W to 17N108W by Wed evening. The gradient ne of the ridge will support moderate to fresh northwest to north winds across the waters n of 28N on Wed, and along the Pacific coast of the Baja California Peninsula, with seas of 4-7 ft building to 5-8 ft Fri and Sat. A northwest to southeast orientated trough will meander east and west over the Baja California Peninsula, and the northern Gulf of California this week, supporting light and variable winds across the Gulf of California waters through early Fri, then moderate southerly flow is expected Fri afternoon through Sat. The pressure gradient between high pressure over the Gulf of Mexico, and lower pressure across the tropical Eastern Pacific continues to combine with a tropical wave along about 92W, to promote fresh to strong northerly winds across the Gulf of Tehuantepec. This northerly flow is expected to persist through early Thursday, with nocturnal winds increasing to around 30 kt late tonight through early Wednesday morning, and again Wednesday night. Seas in the 6-9 ft range will build to 11 ft downstream of the Gulf of Tehuantepec by early each morning. Weaker northeast flow is expected late in the week as the tropical wave shifts west of the area. S of 15N e of 120W: Fresh to strong easterly winds will develop across, and just downstream of the Gulf of Papagayo tonight. The resultant easterly wind waves will mix with long period cross equatorial sw swell that will propagate ne across the waters east of 115W this week. Seas 6 to 8 ft in sw swell are expected across the open Pacific waters between 82W and 113W through Thu night when they will subside to less than 8 ft. W of 120W: See special features above for information on tropical cyclones Darby and Estelle that will pass westward through the central portion this week. Combined seas of 7-11 ft primarily due to mixing swell, are expected to surround the large area of high seas near the the cyclones, and cover the waters elsewhere to the north of 10N this week. $$ Stripling