000 AXPZ20 KNHC 210956 TWDEP Tropical Weather Discussion NWS National Hurricane Center Miami FL 1005 UTC Mon Sep 21 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 0600 UTC surface analysis and satellite imagery through 0845 UTC. ...SPECIAL FEATURES... Tropical Depression Seventeen-E is centered near 16.6N 110.8W at 21/0900 UTC or about 380 nm south of the southern tip of Baja California moving west-northwest at 9 kt. The estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 25 kt with gusts to 35 kt. The depression hasn't shown much change during the past several hours as it remains poorly organized per latest satellite animation and its depiction in an overnight ASCAT pass that showed the surface circulation being elongated northeast to southwest. The satellite imagery shows scattered moderate to isolated strong convection from 12N to 16N between between 110W-114W. Scattered moderate convection is seen from 10N to 14N between 106W-112W and from 10N to 12N between 112W- 115W. The depression is forecast continue on a west-northwestward motion with a slight increase in forward speed expected today and early Tue, followed by a turn toward the west Tue night or early on Wed. It is forecast to become a tropical storm a near 18.5N 114.8W late tonight with maximum sustained winds 35 kt gusts 45 kt. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center at website- https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest Tropical Depression Seventeen-E NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... A tropical wave has its axis along 135W from 03N to a 1009 mb low near 10N135W and north to 18N135W. It is moving westward at 10-15 kt. Scattered showers and isolated thunderstorms are confined to and near the monsoon trough within 180 nm either side of the wave from 09N to 12N. ...INTERTROPICAL CONVERGENCE ZONE/MONSOON TROUGH... The monsoon trough axis extends from northwestern Colombia to 10N86W to 10N95W and to 13N103W, where it ends. It resumes at 14N116W to 12N127W to low pressure near 10N135W 1009 mb and to 09N136W, where overnight scatterometer data indicates that it transitions to the ITCZ to beyond the area at 10N140W. Scattered moderate to isolated strong convection is within 120 nm south of the ITCZ between 136W-140W. Scattered moderate convection is 180 nm south of the trough between between 99W-102W and within 30 nm south of the trough between 132W-135W. OFFSHORE WATERS WITHIN 250 NM OF MEXICO... The gradient induced by weak deep layer ridging between Baja California and 125W is supporting mainly moderate northwest to north winds off Baja California Norte with combined seas to 6 or 7 ft. Winds and seas will diminish some through Tue, except within about 300 nm southwest of the southern tip of Baja California, where much high winds and seas on the periphery of Tropical Depression Seventeen-E can be expected. Farther south, fresh to strong winds will pulse in the Gulf of Tehuantepec region through the next couple of days. Elsewhere, a weak pressure pattern across the region will result in mainly gentle to moderate winds and slight seas. OFFSHORE WATERS WITHIN 250 NM OF CENTRAL AMERICA, COLOMBIA, and WITHIN 750 NM OF ECUADOR... Gentle to moderate south to southwest winds continue south of the monsoon trough. Elsewhere, gentle winds prevail north of the monsoon trough. Combined seas are currently in the 5-6 ft range in a mix of wind waves and southerly swell. Scattered small clusters of moderate convection are along and just some areas of Central American coast. REMAINDER OF THE AREA... A surface trough along 136W from 18N to 23N continues to break up the subtropical ridge and supporting gentle moderate trade winds farther south into the deep tropics. The ridge will gradually build eastward north of 20N through mid week, and trades will strengthen somewhat between the ridge and the monsoon trough. Farther east, seas of 8-9 ft are within an area along the monsoon trough between 105W and 117W. These seas are a result of the fresh to strong southwest to west winds that are occurring in the southern part of the broad cyclonic circulation associated to Tropical Depression Seventeen-E. In addition, persistent long-period southwesterly is present within this area as well further contributing to the build up of these seas. $$ Aguirre