000 AXPZ20 KNHC 301005 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 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 0600 UTC surface analysis and satellite imagery through 0945 UTC. ...SPECIAL FEATURES... Gale Warning: The post-tropical remnant low of former Tropical Cyclone Irwin is centered near 19N132W with a pressure of 1007 mb. It is moving westward at 15 kt. A very tight pressure gradient between the low and strong high pressure to its north is keeping gale-force winds within 60 nm of the low in the NW quadrant 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 north of 19N to a line from 28N130W to 26N140W. These winds were captured bay the same overnight ASCAT pass. Seas with these winds are 8-12 ft. Satellite imagery depicts the low as a large swirl of overcast to broken low and mid-level clouds that covers the area from 16N to 23N between 128W-138W. 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 northwest Colombia to across Panama and to across the south part of Costa Rica. From there is reaches the coast at 09N84W, and continues to 13N100W to 14N108W and to 15N120W. It resumes from 12N129W to beyond 10N140W. Scattered moderate to isolated strong convection is seen within 60 nm north of the trough between 138W-140W. Scattered moderate convection is from 10N to 14N between 109W-111W. ...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 36N142W toward the waters west of the Baja California Peninsula. The pressure gradient between this high and lower pressure over Mexico is supporting moderate to fresh northwest to north winds offshore Baja California. Fresh to locally strong 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 5-7 ft west of Baja California Sur. Seas are 1-3 ft in the Gulf of California. 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 8 ft will slowly subside by Thu. Fresh to locally strong SE to S winds in the far northern Gulf of California will diminish early this morning. Fresh to locally strong S winds will return to the northern Gulf of California 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. Near the Galapagos Islands offshore waters, moderate SE winds with seas of 5-8 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 tonight through Fri. Southerly swell will increase seas to peak of around 9 ft across the Galapagos Island offshore waters tonight, persisting through early Thu before subsiding late Thu. 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 north and northwest of the post-tropical remnant low to a line that extends from 30N130W to 29N140W. These winds were nicely captured by an overnight ASCAT pass. Seas are 7-10 ft in the area, except for higher seas present near the remnant low. Mostly gentle winds are east of 127W from 05N to 20N with seas 5-6 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 03N. 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 in 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 6-9 ft W of Baja California Norte N of 22N and between 121W-137W and E of 130W. Southerly swell in the far southern waters will build seas to 8-10 ft through Wed night. This swell area could travel as far north as 06N between 92W-125W before subsiding Thu. Looking ahead, 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 in about 24 hours, and drift westward afterward through the end of the week. $$ Aguirre