000 AXPZ20 KNHC 130411 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 0405 UTC Sun Sep 13 2020 Tropical Weather Discussion for the eastern Pacific Ocean from the Equator to 32N, east of 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 0300 UTC. ...SPECIAL FEATURES... The 1006 mb low pressure center along the monsoon trough near 16.5N112.5W at 0000 UTC has been upgraded to TROPICAL DEPRESSION SIXTEEN-E at 0300 UTC, located near 16.7N 112.9W 1004 mb. Maximum sustained winds 30 kt gusts to 40 kt moving NW at 8 kt. Scattered to locally numerous moderate to strong convection is seen within 330 nm NW and 210 nm SW quadrants, and has spread to within 30 nm of the center of the T.D. across the southern semicircle in recent hours. Environmental conditions appear conducive for gradual intensification, and it is expected to become a tropical storm Sunday morning as it moves W-NW to NW. Further modest strengthening is expected through late Tue before cooler sea surface temperatures will lead to gradual weakening. Tropical storm force winds and seas to around 12 ft will spread across the outer offshore waters of southwest Mexico and just west of the Revillagigedo Islands late tonight and Sunday, then shift directly across Clarion Island and the surrounding waters late Sun through Sun evening. For more information, see the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPEP1.shtml and Forecast Advisory at https://www.nhc.noaa.gov/text/MIATCMEP1.shtml. ...TROPICAL WAVES... A tropical wave extends along 90W across Guatemala and El Salvador into the eastern Pacific, moving westward at 10 kt. Associated convection is mainly occurring over land across Central America and behind the wave extending offshore of Costa Rica and Nicaragua, and is described below. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from 10N75W to 09N80W to 10N93W to 1006 mb low pressure near 16.5N112.5W to 1007 mb low pressure near 17N119W to 10N135W to 10.5N140W. Scattered moderate to strong convection is noted from 06N to 11N between 81W and 89W. Widely scattered moderate isolated strong convection from 09 to 16N between 90W and 99W. Scattered moderate to strong convection is noted from 09N to 13N between 101.5W and 107W. Scattered moderate convection is noted from 09.5N to 13N between 115W and 130W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... Please see the Special Features section above for more details on TROPICAL DEPRESSION SIXTEEN-E. SE winds of 20 to 30 kt and seas 8 to 11 ft will shift NW across the outer offshore waters west of Cabo Corrientes and across western portions of the Revillagigedo Islands. Southerly swell from this system will spread across the Baja California offshore waters Sunday through early next week. Afternoon scatterometer data show gentle to moderate northerly winds over the Baja California waters north of Cabo San Lazaro, with gentle to moderate NW winds in the central Gulf of California. Earlier convection noted near the entrance to the Gulf of California has ended. Elsewhere, light to gentle winds prevail along the coast of southern Mexico, where a recent altimeter pass indicates seas are 4-6 ft. Modest pulses of moderate to locally fresh northerly gap winds are expected tonight and Sun night over the Gulf of Tehuantepec. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gentle to moderate S to SW winds persist south of the monsoon trough, which extends across the offshore waters roughly along 10N-11N. Elsewhere, winds remain gentle north of the trough near the coast of Guatemala, El Salvador, and Nicaragua, except for higher gusts in monsoon trough convection across the waters of Costa Rica and Nicaragua. Combined seas remain 4-7 ft in wind waves and background S to SW swell. Gentle to moderate monsoonal flow will prevail over the waters generally S of 10N for the next several days. Combined seas may slightly increase in the waters E of 90W Tue night through Wed as S to SW swell moves across the region. REMAINDER OF THE AREA... Increasing winds and seas will be seen northwest of Clarion Island and spread northwestward over the next several days as TROPICAL DEPRESSION SIXTEEN-E moves west-northwestward away from the coast of Mexico and strengthens to a Tropical Storm. Elsewhere, 1007 mb low pressure along the monsoon trough near 17N119W is producing scattered moderate isolated strong convection from 90 to 210 nm across the W semicircle. Additional development of this system is becoming less likely over the next day or so before it interacts with, and is possibly absorbed by TROPICAL DEPRESSION SIXTEEN-E. This system has a low chance of tropical cyclone formation during the next 48 hours. A weak and narrow high pressure ridge extends across the NW portion from 1018 mb high pressure near 30N131W to 26N140W. South of the ridge, mainly moderate NE trades prevail across the waters north of the monsoon trough, with smaller pockets of fresh winds noted in scatterometer data between 120W and 130W. Combined seas are generally 5-7 ft based on recent altimeter data, possibly peaking around 8 ft within the fresh flow. A broad area of fresh to locally strong monsoonal flow is shown south of the trough between 110W and 125W, with seas generally 6-9 ft in this region. Decaying, long-period S to SW swell lingers across the waters E of 120W, with 7-8 ft combined seas south of the equator. Looking ahead, new southerly swell may move across the southern waters during the early to middle parts of next week. $$ Stripling