000 AXPZ20 KNHC 061005 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Sep 6 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... Low pressure of 1008 mb is located along the monsoon trough near 16.5N105W, or a couple of hundred miles south-southeast of Manzanillo, Mexico moving northwest near 10 kt. Recent and current satellite imagery show that convection of the scattered moderate to isolated strong type is increasing within 90 nm of the low in the NW semicircle and within 60 nm of the low in the SE semicircle. Large clusters of numerous moderate to strong convection are north of the low from 18N to 21N between 104W- 107W. Environmental conditions appear conducive for gradual development of this system during the next couple of days, and a tropical depression is likely to form while it moves west- northwestward or northwestward. This system has a medium chance of becoming a tropical cyclone during the next 48 hours. Please refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. ...TROPICAL WAVES... The southern part of the axis of a Caribbean Sea tropical wave extends into the far eastern Pacific along 79W and north of 07N. It is moving westward at 10 kt. Isolated showers and thunderstorms are along and near the wave axis. A tropical wave has its axis along 91W north of 05N to well inland Guatemala, It is moving westward at 10-15 kt. No significant convection is noted with this wave. A tropical wave has its axis along 128W from 05N to 18N, moving westward at 10-15 kt. This wave is moving through a rather stable surrounding environment. Scattered moderate convection is within 120 nm east of the wave axis from 10N to 11N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from northwestern Colombia near 11N76W to across northern Costa Rica to 12N93W to the 1008 mb low near 16.5N105W and to 14N115W to 12N124W to 11N132W to west of the area at 11N140W. Aside from convection associated to the 1008 mb low and tropical waves, scattered moderate to isolated strong convection is noted from 09N to 12N between 95W-99W and within 60 nm north of the trough between 96W-99W. Scattered moderate convection is within 30 nm north of the trough between 116W-121W, within 30 nm south of the trough between 122W-126W, and within 30 nm north of the trough between 130W-133W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for details on a low pressure system centered a couple hundred miles south- southeast of Manzanillo, Mexico. A weak trough extends from 30N118W to near 24N122W. No convection is occurring with this trough as it is surrounded by a very dry and stable environment. Gentle to locally moderate NNW winds are noted off the Baja California peninsula with seas to 5 ft in long-period S to SW swell. In the Gulf of California, light to gentle variable winds with seas less than 3 ft prevail. A convective complex of scattered moderate intensity has moved off the Mexican mainland during the overnight hours and is over the central portion of the Gulf of California. This activity is being driven by an upper-level disturbance that is riding westward along the southern periphery of a mid to upper-level ridge that extends from the western U.S. west to the Pacific Ocean near 126W. Light to gentle variable winds are also across the Nayarit offshores while moderate to fresh SE winds are observed off the coasts of Jalisco to Guerrero. Seas are up to 7 ft in long-period SW swell. Otherwise, increasing scattered showers and thunderstorms are observed over the offshore waters of Oaxaca to Jalisco. Winds will continue to be light to gentle off the Baja Peninsula through Mon with locally moderate winds with seas to 4 ft. Gentle to moderate NW winds will return tonight and increase to moderate to fresh by Tue evening as the Special Features low pressure system approaches from the SE. In the Gulf of California, SE winds have recently increased to moderate to locally fresh speeds, with seas to 4 ft. These winds are expected to return to light tonight and continue through Thu. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Light to moderate southwest winds are south of the monsoon trough, while light and variable winds are north of the monsoon trough, except in the Gulf of Papagayo region where moderate NE winds are present. Seas are 3 to 6 ft in the Central American offshore waters with 6 to 7 ft seas off of Ecuador and the Galapagos Islands. Isolated showers and thunderstorms are over the offshore waters of Costa Rica and Colombia, while scattered showers and isolated thunderstorms are increasing over the offshore waters of Panama. Scattered moderate to isolated strong convection is along the coast of Colombia south of 04N and extends a good distance inland. Seas are 3 to 6 ft in the Central American offshore waters, except for higher seas of 6 to 7 ft over the waters between Ecuador and the Galapagos Islands due to a SW swell. These seas will increase slightly to 6-8 ft Mon night and Tue. Winds in Papagayo region will pulse gentle to locally moderate through Wed. Moderate to locally fresh SW winds are expected along the regions of Costa Rica, Panama, Colombia, Ecuador and Galapagos Islands Tue through Thu. Seas in this area will remain in the 6 to 7 ft range, except for 8 ft in the region W of Ecuador. 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 locally fresh NNE winds and seas of 6 to 8 ft for the are north of about 12N and W of 120W. Gentle to moderate southerly winds remain south of the monsoon trough, with seas to 7 ft. An area of slightly stronger winds, in the fresh range, was noted in an overnight ASCAT pass to be confined between 118W-123W. Satellite imagery shows what appears to be a low forming along the monsoon trough near 13N119W. The low could be at the mid- levels as inferred from satellite imagery. Seas to 8 ft due to a SW swell continue south of the Equator and W of the Galapagos Islands. Otherwise, an area of low pressure is forecast to form in a few days well to the southwest of the southern tip of the Baja California peninsula. Some slow development is possible thereafter while the system meanders over the open eastern Pacific Ocean. This system has a low chance of development in the next 48 hours and 5 days. Otherwise, moderate to fresh NNE winds are forecast for the northern waters W of Baja California by late Mon, continuing through Wed. $$ Aguirre