000 AXPZ20 KNHC 121600 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1605 UTC Fri Nov 12 2021 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 1545 UTC. ...SPECIAL FEATURES... Gulf of Tehuantepec Gale Warning: The pressure gradient between high pressure that will build in behind a Gulf of Mexico cold front and lower pressure S of Mexico will result in the development of a gale-force gap wind event over the Gulf of Tehuantepec beginning Sat morning. Model guidance indicates that peak winds will be near 40 kt Sat night, with seas to near 12 ft. Swell generated by this event will propagate downstream of the Gulf of Tehuantepec, with seas 8 ft or greater reaching as far south as 10N and west to near 103W on Sun. Winds are forecast to drop below gale-force Sun into Mon, then increase back up to gale-force at similar speeds Mon evening. Please see the latest NWS High Seas Forecast issued by the National Hurricane Center at website://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for more information. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from 08N78W to 10N87W to 07N98W, where overnight scatterometer data indicates that it transitions to the ITCZ to 07N100W to 07N120W to a 1009 mb low pressure near 12N129W to beyond 09N140W. Scattered moderate convection is within 120 nm south of the ITCZ between 133W-137W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for details on an upcoming Gulf of Tehuantepec gale event. Surface ridging continues to extend to the Baja California Norte offshore waters, supporting gentle to locally moderate NW winds to Cabo San Lazaro and light to gentle variable winds along the southern and southwestern Mexican offshore waters. Northwest swell is generating seas in the 5-6 ft range west of the Baja California peninsula, while southwest swell is supporting seas of 4-5 ft across the southern and southwestern offshore waters. Otherwise, moderate to fresh northerly winds are funneling along the Gulf of California being supported by a tighter pressure gradient between the ridge to the west and a surface trough along western Mexico. Seas are 3-4 ft in the Gulf of California. Moderate winds offshore of Baja California will gradually diminish to gentle through this afternoon as high pressure north of the area weakens. Fresh north winds inside the Gulf of California will diminish to gentle to moderate by this evening. Strong to near gale-force north winds in the Gulf of Tehuantepec region are expected to reach gale-force Sat morning as high pressure builds in behind another cold front that is forecast to sweep across the southern Gulf of Mexico. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR Moderate to fresh gap winds remain across the Papagayo region, with gentle to moderate winds elsewhere north of the monsoon trough. These winds may briefly pulse to strong speeds on Sun. Gentle to moderate south to southwest winds are south of the monsoon trough with seas in the 4-6 ft range in southwest swell. These winds will persist through the forecast period. REMAINDER OF THE AREA... A strong center of high pressure remains north of the area with a ridge extending south to 19N and W of about 124W. The resultant pressure gradient between the ridge and lower pressure in the vicinity of the ITCZ is supporting moderate to fresh northeast to east winds north of the ITCZ to 27N and west of 120W. Low pressure of 1009 mb ,the remnants of former tropical cyclone Terry, is near 12N129W. Satellite imagery shows scattered moderate to isolated strong convection from 09N to 13N between 123W-128W, and within 30 nm of a line from 11N128W to 10N131W. Scattered moderate convection is within 30 nm either side of a line from 15N125W to 14N127W. A tight gradient between the low and the aforementioned ridge is leading to fresh to strong northeast to east winds north of the low to near 14N and between 126W-129W. This low is forecast to move in a general westward motion over the next 24 to 30 hours while it weakens, eventually to a trough over the far western part of the area by early Sun. Gentle to moderate winds prevail south of the ITCZ. Elsewhere, seas are in the 8-10 ft range due to mixed northeast and northwest swell across the trade wind belt west 120W. Seas in the 6-8 ft range are elsewhere. The aforementioned high pressure ridge will remain across the northern waters maintaining a zone of fresh trades south of about 23N and west of 124W through most of Sat. These trades will gradually decrease in coverage through the weekend as the surface trough continue to move westward. As a consequence, seas will subside to 8 ft across the trade wind belt, but confined to west of 135W by Sun. $$ Aguirre