000 AXPZ20 KNHC 071003 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Tue Sep 7 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 0600 UTC surface analysis and satellite imagery through 0945| UTC. ...SPECIAL FEATURES... Gale Warning: A gale warning is in effect for the offshore waters of Mexico from Jalisco to offshore central and southern Baja California from Wed through Fri night. This is due to an area of low pressure that is located a couple of hundred miles south- southwest of Manzanillo, Mexico. The low pressure of 1009 mb is analyzed near 18N107W. Satellite imagery shows scattered moderate to isolated strong convection within 180 nm of the low in the NE quadrant and within 90 nm of the low in the SE quadrant. Environmental conditions are conducive for additional development, and this system is likely to become a tropical depression during the next day or so while it moves generally west-northwestward, just offshore of the coast of Mexico. Regardless of development, outer rainbands from the disturbance are likely to produce locally heavy rainfall and gusty winds along the coast of the Mexican states of Colima and Jalisco today. This system has a high chance of becoming a tropical cyclone during the next 48 hours. Please see the latest NWS High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFEP2.shtml for further details on the gale warning and refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details on the low pressure system. ...TROPICAL WAVES... A tropical wave has its axis along 86W north of 02N to inland central Honduras and Nicaragua. It is moving westward at 10 kt. Scattered moderate convection is within 60 nm either side of the wave from 08N to 10N. A tropical wave has its axis along 96W north of 02N to inland southeastern Mexico. It is moving westward at 10 kt. Isolated showers and thunderstorms are within 60 nm east of this wave from 09N to 11N. A tropical wave has its axis along 136W from 02N to 15N, moving westward at 10-15 kt. Scattered moderate to isolated strong convection is within 180 nm west of the wave from 10N to 13N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from just inland northwestern Colombia to across southern Honduras and to 14N97W to the Special Features low pressure near 18N107W 1009 mb to 14N115W to 12N125W to 11N135W and to 11N140W. Aside from the convection associated with the 1009 mb low and the tropical waves, numerous moderate to isolated strong convection is noted from 09N to 14N between 85W-90W, within 60 NM north of the trough between 136W- 138W and within 60 nm south of the trough between 138W-140W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for details on a gale warning due to an evolving low pressure system centered a couple of hundred miles south-southwest of Manzanillo, Mexico. A weak trough extends from 30N120W to near 25N122W. No convection is occurring with this trough as it is surrounded by a very dry and stable environment. Latest scatterometer data depicts gentle to moderate NW winds off the Baja California peninsula with seas to 4 ft in long-period S to SW swell. Overnight ASCAT data revealed light to gentle variable winds across the Gulf of California. Seas are less than 3 ft, except 3-4 ft just south of the entrance to the Gulf. Rather quite conditions prevail across the Gulf of California with no significant convection noted there, however scattered moderate to isolated strong convection is just inland Mexico from northern Jalisco to southern Sonora. Fresh to strong east-southeast winds are seen off the coasts of Jalisco to Guerrero due to a tight gradient between the 1009 mb low pressure system and the coast of Mexico. Earlier altimeter data showed seas up to 8 ft in that area. Otherwise, light to gentle variable winds are across the Nayarit offshores in addition to Oaxaca and Chiapas. Seas are 6-7 ft in long-period southwest swell. Numerous showers and thunderstorms associated with the 1009 mb low are quickly increasing along and offshore the coasts of the states of Jalisco and Nayarit. Winds will continue to be gentle to moderate off the Baja Peninsula tonight through Tue with seas to 5 ft. By tonight, winds will become moderate to fresh as the low pressure system in the Special Features approaches the region from the SE. This system is expected to move across the offshores of the Baja Peninsula Wed through the end of the week with building seas and strong winds. In the Gulf of California, winds are expected to return to light tonight and continue through Thu night. Light to gentle winds will continue across southern Mexico. Fresh to strong gaps winds could develop across the Gulf of Tehuantepec beginning Thu night and continuing into the weekend. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Latest scatterometer data depicts moderate to locally fresh winds continue across the Gulf of Papagayo. Meanwhile, gentle to moderate southwest winds are south of the monsoon trough with light and variable winds are north of the monsoon trough. Seas are 3-6 ft in the Central American offshore waters and 6-7 ft seas off of Ecuador and the Galapagos Islands. Satellite imagery shows strong thunderstorms are beginning to move off of the coast of Nicaragua to Panama into the adjacent offshore waters. Isolated thunderstorms are noted along the coast of Colombia. Seas are 3-6 ft in the Central American offshore waters, except for higher seas of 6-7 ft over the waters between Ecuador and the Galapagos Islands due to a southwest swell. Winds in Papagayo region will pulse moderate to locally fresh through Thu. Moderate to locally fresh SW winds are expected along the offshore waters of Costa Rica, Panama, Colombia, Ecuador and Galapagos Islands Tue through the end of the week. Strong south to southwest winds are expected over the offshore waters of Guatemala and El Salvador late Sat as low pressure develops over or near those waters. Seas in this area will remain in the 6-7 ft range, except near 8 ft seas in the region west of Ecuador. Seas offshore Guatemala, Honduras and El Salvador are expected to build to possibly 9 ft during Sat and Sat night due to the expected strong south to southwest winds combining with southwest swell that will be propagating through those same offshore waters. REMAINDER OF THE AREA... Broad high pressure dominates the waters north of the monsoon trough, with the gradient between it and lower pressure to the south in the monsoon trough region allowing for moderate to fresh NNE winds and seas 7 ft south of 15N and west of 115W. Gentle to moderate southerly winds remain south of the monsoon trough, with seas to 7 ft. Seas to 8 ft due to a southwest swell continue south of the Equator and west of the Galapagos Islands through early Wed, then another set of southwest swell will again begin to propagate through the waters west of the Galapagos Islands late from Thu through the upcoming weekend. A small low pressure area located about 780 nm southwest of the southern tip of the Baja California peninsula is producing disorganized showers and thunderstorms. Development, if any, of this system is likely to be slow over the next day or two while it drifts northward. After that time, environmental conditions are expected to become unfavorable for further development. This system has a low chance of development in the next 48 hours and 5 days. Otherwise, winds will begin to relax along the monsoon trough by Tue through the rest of the week. $$ Aguirre