000 AXPZ20 KNHC 302128 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 2104 UTC Sun Jul 30 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 25.0N 127.2W at 30/2100 UTC or about 930 nm W of the southern tip of Baja California moving WNW at 12 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Isolated moderate convection is within 90 nm N quadrant. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP4/WTPZ24 for more details. Tropical Storm Irwin is centered near 18.5N 125.6W at 30/2100 UTC or about 925 nm WSW of the southern tip of Baja California moving NNW at 8 kt. Estimated minimum central pressure is 996 mb. Maximum sustained wind speed is 55 kt with gusts to 65 kt. Scattered moderate and isolated strong convection is within 90 nm of center. See latest NHC forecast/advisory under AWIPS/WMO headers MIATCMEP5/WTPZ25 for more details. ...TROPICAL WAVES... A tropical wave extends from 07N83W to 09N84W then continues farther north through Costa Rica and eastern Nicaragua, moving W at 10 to 15 kt. No significant convection over the water. A tropical wave extends from 07N92W to 14N92W moving W at 10 to 15 kt. Scattered moderate convection is from 07N to 11N between 90W and 95W. A tropical wave extends from 08N106W to 18N106W moving W at 10 to 15 kt. Isolated moderate convection is from 13N to 18N between 105W and 107W. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 09N84W to 08N90W to 11N116W then resumes from 14N128W to 10N140W. No significant intertropical convergence zone is noted W of 140W. Other than convection already described in the tropical wave section, no significant convection is observed. ...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 this afternoon. With Hilary well west of the area...a narrow surface ridge extends between the cyclone and Baja California, which is expected to result in moderate to fresh NW winds tonight through Monday night. As these winds increase, seas will build to 7 to 9 ft as these wind waves combine with 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 today, and the waters between Los Cabos and Cabo Corrientes late tonight 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 region, moderate E-NE winds prevail with seas of 5 to 7 ft in a mix of E wind waves and long period SW swell. Winds will veer southeasterly and diminish slightly tonight there. On 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 today, with seas 8 to 10 ft reaching as far north as 13N/14N. Thereafter, this area of seas will gradually subside starting late Sunday night into early Monday. REMAINDER OF THE AREA... A 1027 mb high is located N of the area near 38N136W with a ridge axis extending to just offshore of Baja California Norte near 31N119W. 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 127W through tonight. Long period cross equatorial SW swell of 8 to 9 ft is spreading across the waters S of 10N and E of 110W, and will persist through tonight. 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 remnant 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. $$ Christensen