000 AXPZ20 KNHC 282141 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2109 UTC Fri Jul 28 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 1800 UTC surface analysis and satellite imagery through 2100 UTC. ...SPECIAL FEATURES... Tropical Storm Hilary is centered near 19.7N 119.2W at 28/2100 UTC or about 555 nm WSW of the southern tip of Baja California moving NW at 8 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 18N to 21N between 115W and 120W. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 for more details. Tropical Storm Irwin is centered near 14.9N 125.0W at 28/2100 UTC or about 980 nm WSW of the southern tip of Baja California and is nearly stationary. Estimated minimum central pressure is 998 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt. Scattered to numerous moderate and isolated strong convection is from 13N to 17N between 125W and 130W. See latest NHC forecast/ advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 for more details. ...TROPICAL WAVES... A tropical wave extends from 07N97W to 15N96W moving W at 10 to 15 kt. Scattered moderate convection is from 11N to 14N between 95W and 100W. A tropical wave extends from 06N112W to 16N112W moving W at 5 to 10 kt. No significant convection is observed. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N85W to 08N100W to 10N110W then resumes near 11N130W to 09N137W. The ITCZ extends from 09N137W to 09N140W. Scattered to moderate and isolated strong convection is within 120 nm either side of the monsoon trough between 95W and 110W. ...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. Seas of 6 to 8 ft associated with tropical cyclone Hilary have been impacting the waters in near Clarion Island, but should be subsiding through tonight as Hilary continues to move farther to the NW. Hilary's movement will also allow a ridge axis to fill in between the departing cyclone and Baja California, which in turn will result in moderate to fresh NW winds Sunday through early next week. As these winds increase, seas will build again into a range of 7 to 9 ft due to another round of long-period southerly swell. 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 on 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 fresh winds to develop tonight and again Saturday night 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. Otherwise, gentle to moderate S to SW winds are expected the next few days. Strong long period cross-equatorial S-SW swell will continue to propagate into the forecast waters through Saturday, 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. REMAINDER OF THE AREA... High pressure is located N of the area with a ridge axis extending across the northern forecast waters N of 25N. The pressure gradient between this system and the active zone of tropical cyclones will maintain moderate to fresh N to NE winds W of 120W through Saturday. Long period cross equatorial SW swell of 8 to 9 ft will spread across the waters S of 10N and E of 110W, persisting through Sunday night. As the tropical cyclone activity shifts to the NW over the discussion waters later this weekend, 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 115W early next week. $$ Christensen