000 AXPZ20 KNHC 240239 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Tue Aug 24 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 0000 UTC surface analysis and satellite imagery through 0120 UTC. ...SPECIAL FEATURES... Tropical Storm Marty is centered near 20.7N 115.8W at 24/0300 UTC moving W at 15 kt. Estimated minimum central pressure is 1002 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Peak seas are currently 13 ft. Scattered moderate convection is sheared off and noted within 240 nm in the southwest semicircle of Marty. Marty will weaken to a tropical depression Wed morning, and become a remnant low Wed evening. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPEP3.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMEP3.shtml for more details. A broad area of low pressure located less than 200 nm offshore of Guatemala and southern Mexico is producing some disorganized showers and thunderstorms. Environmental conditions are forecast to be favorable for gradual development of this system, and a tropical depression is likely to form by the middle to latter part of this week. The system is expected to move westward to west-northwestward at 10 to 15 kt this week, passing offshore of the coast of southwestern Mexico. This system has a medium chance for tropical development within the next 48 hours, and a high chance within the next 5 days. Refer to the National Hurricane Center Tropical Weather Outlook at www.hurricanes.gov for details. ...TROPICAL WAVES... The southern portion of a tropical wave extends along 85W and north of 03N, moving W at 5 to 10 kt. Associated convection is described in the section below. A tropical wave is along 93W and north of 03N, moving W at 10 to 15 kt. Scattered moderate and isolated strong convection is noted from 07N to 17N between 88W and 100W. A tropical wave is along 113W/114W from 01N to 15N, moving W at around 15 kt. Associated convection is described in the section below. A tropical wave is along 129W from 01N to 18N, moving W at 10 to 15 kt. Associated convection is described in the section below. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough extends from northern Colombia near 10N73W to 09N80W to 14N105W to 11N122W to 13N130W to 11N140W. Aside from the convection described in the Tropical Waves section above, scattered moderate and isolated strong convection is noted from 11N to 19N between 100W and 110W. Similar convection is noted within 120 nm offshore of Central America and Mexico east of 93W. Scattered moderate convection is noted from 09N to 13N between 111W and 131W, and also from 08N to 10N west of 135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Refer to the Special Features section above for details on Tropical Storm Marty and the other area of interest. Gentle to moderate southerly winds prevail in the Gulf of California, with gentle to moderate NW-N winds offshore of Baja California outside of Marty. Moderate to fresh SE winds are being funneled along the coast and across the offshore waters of Guerrero and Michoacan. Seas across the offshore waters of Mexico outside of Marty are 4 to 7 ft, except 3 ft or less in the Gulf of California, and to 8 ft in the area of moderate to fresh winds. Fresh to strong N-NE winds are in the Gulf of Tehuantepec along with 5 to 7 ft seas. For the forecast, aside from Marty and the area of disturbed weather off the coast of southern Mexico, gentle to moderate southerly flow will prevail in the Gulf of California. Fresh to strong N-NE winds will continue to pulse through midweek. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Scattered showers and isolated thunderstorms are continuing along the coast and offshore waters from Colombia northward under the influence of moist monsoonal winds, and the passage of two tropical waves across the region. Moderate E-SE winds prevail offshore of Nicaragua northward. Moderate S-SW winds prevail south of the monsoon trough. Seas of 4 to 7 ft in mixed long period swell dominate the offshore waters. For the forecast, gentle to moderate winds will prevail north of the monsoon trough, pulsing to fresh in the Papagayo region. Moderate to fresh S to SW winds south of the monsoon trough will diminish somewhat by the end of the week. Long period SW swell will reach the coast of Central America tonight with a somewhat larger and reinforcing set from the middle through the end of the week. REMAINDER OF THE AREA... Refer to the Special Features section above for details on Tropical Storm Marty. Broad surface ridging dominates the waters north of the monsoon trough. Gentle to moderate N-NE winds prevail north of the monsoon trough, with mainly moderate to fresh southerly winds south of the monsoon trough, locally to strong. Seas of 4 to 7 ft dominate most of the waters, except near the locally strong winds where seas are 7 to 9 ft. For the forecast, trades north of the monsoon trough will gradually increase to moderate to fresh as the pressure gradient tightens. Otherwise, little change in marine conditions is forecast through the week. A set of northerly swell may push south into the area during the upcoming weekend with building seas. $$ Lewitsky