000 AXPZ20 KNHC 291512 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1510 UTC Sat Jul 29 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 1415 UTC. ...SPECIAL FEATURES... Tropical Storm Hilary is centered near 21.4N 121.5W at 29/1500 UTC or about 650 nm W of the southern tip of Baja California moving NW at 9 kt. Estimated minimum central pressure is 996 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered moderate convection is from 19N to 23N between 117W and 122W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 for more details. Tropical Storm Irwin is centered near 15.1N 124.9W at 29/1500 UTC or about 970 nm WSW of the southern tip of Baja California moving N at 2 kt. Estimated minimum central pressure is 998 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt. Scattered moderate convection is from 11N to 16N between 123W and 127W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 for more details. ...TROPICAL WAVES... A tropical wave extends from 06N86W to 14N87W moving W at 10 to 15 kt. Scattered moderate convection is from 09N to 10N between 84W and 87W. A tropical wave extends from 06N102W to 17N101W moving W at 10 to 15 kt. Scattered moderate and isolated strong convection is from 11N to 17N between 96W and 103W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N79W to 09N84W to 10N91W to 12N96W to 10N106W to 15N116W. The ITCZ extends from 10N135W to 10N140W. Scattered moderate and isolated strong convection is N of 06N E of 81W...and from 09N to 15N between 88W and 94W. Scattered moderate convection is from 05N to 08N between 90W and 96W...from 07N to 17N between 112W and 118W...and from 08N to 10N between 132W and 139W. ...DISCUSSION... OFFSHORE WATERS WITHIN 250 NM OF MEXICO... High pressure centered NW of the area will support gentle to moderate NW winds within 120 nm of the Baja California peninsula through Sunday. Tropical Cyclone Hilary's affects are now mainly west of the area, with some small southerly swell to fade across the far outer waters through tonight. The NW movement of the system will allow a ridge axis to fill in between the departing cyclone and Baja California, which will result in moderate to fresh NW winds Sunday through Monday night. As these winds increase, seas will build into a range of 7 to 9 ft as the wind waves combine with a round of long-period southerly swell moving into the region during the next few days. Cross equatorial long period southerly swell with seas of 7 to 8 ft will reach the offshore waters between the Gulf of Tehuantepec and Cabo Corrientes on Sunday, and the waters between Los Cabos and Cabo Corrientes late Sunday night into early Monday. Elsewhere, generally moderate NW winds and seas of 5 to 7 ft will prevail. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Across the Gulf of Papagayo, expect moderate to occasional fresh winds to develop tonight with the assistance of the nocturnal drainage flow, building maximum seas of 6 to 7 ft in a mix of E wind waves and long period SW swell. By Monday...global models are suggesting a weak area of low pressure to develop in the vicinity of 10N90W and move generally westward through Tuesday and then more W-NW through Wednesday. Likely S-SW monsoonal flow will build seas to 7 to 9 ft across the waters S of Guatemala and the Gulf of Tehuantepec coastline. Elsewhere, gentle to moderate S to SW winds are expected the next few days. Large long period cross-equatorial S-SW swell will continue to propagate into the forecast waters during the weekend, with seas 8 to 9 ft reaching as far north as 10N by tonight. The area of 8 ft seas will then reach just offshore all Central America Pacific coastal sections by Sunday. Seas will gradually subside starting Monday. REMAINDER OF THE AREA... A 1027 mb high is located N-NW of the area near 37N136W with a ridge axis extending to 28N124W. The pressure gradient between the high pressure system and the active zone of tropical cyclones will maintain moderate to fresh N to NE winds W of 120W through Sunday. Long period cross equatorial SW swell of 8 to 9 ft will spread across the waters S of 10N and E of 110W today, persisting through Sunday night. As the tropical cyclone activity shifts to the NW and eventually weakens across the northwestern discussion waters, a weak pressure pattern will develop between the cyclones and the equatorial trough to the south. This will result in a broadening area of gentle to moderate winds between 10N and 20N, W of 110W early next week. $$ HUFFMAN