000 AXPZ20 KNHC 301556 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Wed Aug 30 2023 Tropical Weather Discussion for the eastern Pacific Ocean from 03.4S to 30N, east of 120W including the Gulf of California, and from the Equator to 30N, between 120W and 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 1530 UTC. ...SPECIAL FEATURES... Gale Warning: The post-tropical remnant low of former Tropical Cyclone Irwin is centered near 19.5N 133.5W with an estimated central pressure of 1006 mb. It is moving westward at 10 to 15 kt. A very tight pressure gradient between the low and strong high pressure to its north is keeping gale-force winds within 45 nm of the low in the northern semicircle along with seas of 10-15 ft. An overnight ASCAT data pass depicted these winds. Strong to near gale-force northeast winds cover a large area elsewhere to the north and northwest of the low, roughly from 19N to 25N between 132W and 138W. Seas with these winds are 9-12 ft. Scattered moderate convection has developed from 19N to 21N between 132W and 134W. The remnant low is forecast to continue moving westward, with a slower motion expected later this week. The pressure gradient should ease just enough in about 6 hours allowing for the gale-force winds to diminish to strong to near gale speeds. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more details. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from Panama near 08N78W to Costa Rica near 09N84W to 13N104W to 13N118W. The monsoon trough resumes from 13N132W to 10N140W. Scattered moderate convection is noted from 09N to 12N between 86.5W and 89W, from 06N to 15N between 99W and 115W and from 09N to 15N between 127W and 140W. ...OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Surface high pressure ridging extends southeastward from strong high pressure of 1031 mb that is analyzed well north of the area near 36N143W toward the waters west of the Baja California peninsula. The pressure gradient between this ridge and lower pressure over Mexico is supporting moderate northwest to north winds within 180 nm to the west of Baja California, and moderate to fresh between 180-250 nm west of Baja California. Fresh SE to S winds are in the northern Gulf of California. Gentle to locally moderate winds prevail elsewhere. Seas of 6-9 ft prevail west of Baja California Norte with 4-7 ft west of Baja California Sur. Seas are 1-3 ft in the Gulf of California, except 4 ft in the northern Gulf. Seas elsewhere offshore of Mexico are generally 4-5 ft. For the forecast, moderate to fresh NW winds west of Baja California north of Cabo San Lazaro will persist today. Northerly swell producing seas to 7 to 9 ft will slowly subside to 5 to 7 ft by Thu. Fresh SE to S winds in the far northern Gulf of California will diminish early this afternoon. Fresh to locally strong S winds will return to the northern Gulf of California briefly this evening, then return again Thu night through early Sat. ...OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, AND WITHIN 750 NM OF ECUADOR... Light to gentle southwest winds prevail across most of the offshore waters N of 02N along with seas of 4-5 ft in long- period south to southwest swell. In between Ecuador and the Galapagos Islands, moderate S winds with seas of 7-9 ft are present due to long-period south swell. For the forecast, moderate south to southwest winds will prevail between the coast of Ecuador and the Galapagos Islands through Fri. Southerly swell will keep seas around 7 to 9 ft through early Thu before subsiding late Thu. Renewed long period S to SW swell will move through those waters late Fri, increasing seas again to 7 to 9 ft through Sat. Elsewhere, light to gentle variable winds will prevail through most of the week with slight to moderate seas in long-period SW swell. ...REMAINDER OF THE AREA... Please see the Special Features section for details on a Gale Warning related to Post-Tropical Cyclone Irwin. The pressure gradient between high pressure north of the area and the post-tropical remnant low of Irwin is inducing a large area of fresh to strong NE winds extending northwest of a line from 30N120W to 16N137W. Seas are 7-9 ft in the area, except 10 to 15 ft near the remnant low of Irwin. Mostly gentle winds are east of 128W from 05N to 20N with seas 5-7 ft. Moderate SE winds are south of 05N. Long-period S swell has raised seas to the range of 8-10 ft over the southern part of the area, to the south of 06N. For the forecast, the post-tropical remnant low of Irwin is forecast to continue in a general westward motion through the rest of the week crossing 140W early on Fri. As it does, the fresh to strong winds to its north will translate to west of the discussion area. Elsewhere, northerly swell will propagate through the open waters well W of Baja California through at least Thu night, keeping seas of 6-10 ft W of Baja California Norte N of 22N and between 121W-137W. Southerly swell in the far southern waters to the south of 06N will keep seas 8-10 ft through tonight. This swell area will subside Thu. Another long period S swell event will push northward across the Equator on Fri, with seas of 8-9 ft south of 05N and east of 120W into Sat before subsiding late in the weekend. Also, indications in the global model pressure fields are that broad troughing could set up to the SW of Baja California starting tonight, and drift westward afterward through the end of the week. $$ Hagen