000 AXNT20 KNHC 200507 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 105 AM Thu Aug 20 2020 Tropical Weather Discussion for North America, Central America Gulf of Mexico, Caribbean Sea, northern sections of South America, and Atlantic Ocean to the African coast from the Equator to 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 0000 UTC surface analysis and satellite imagery through 0440 UTC. ...SPECIAL FEATURES... Newly formed Tropical Depression Thirteen is located near 14.6N 47.W at 20/0300 UTC, or about 900 miles ESE of the northern Leeward Islands. TD Thirteen has sustained maximum winds of 30 kt with gusts to 40 kt and is moving WNW at 17 kt. It has an estimated minimum central pressure of 1008 mb. Scattered moderate convection is noted within 300 nm of the center in the NW quadrant and within 200 nm in the southern semicircle. Seas are up to 9 ft near the center. On the forecast track, the depression is expected to move near or north of the northern Leeward Islands by late Friday and near or north of the Virgin Islands and Puerto Rico on Saturday. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT3.shtml and Forecast/Advisory at https://www.nhc.noaa.gov/text/MIATCMAT4.shtml for more details. A Caribbean Sea tropical wave is near 75W from eastern Cuba southward with a 1008 mb low centered near 15N75W. The wave is moving westward at 15-20 knots and is producing a concentrated area of showers and thunderstorms over the central Caribbean Sea. This system is gradually becoming better organized, and a tropical depression is likely to form in a couple of days when the system reaches the northwestern Caribbean Sea. This low pressure area is moving westward, and interests in Honduras and the Yucatan Peninsula should closely monitor its progress. Regardless of development, this disturbance will likely produce heavy rains across a large portion of Central America and southeastern Mexico late this week and this weekend. Formation chance through 48 hours is high. Please refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov, for more details. ...TROPICAL WAVES... An Atlantic Ocean tropical wave has an axis along 42W from 19N southward and is moving westward 15-20 knots. No significant deep convection is occurring currently in association with this wave. An Atlantic Ocean tropical wave has an axis along 57W from 20N southward and is moving westward 15-20 kt knots. Scattered thunderstorms are noted from 11N-20N between 55W-59W. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal areas of Mauritania near 19N16W to 12N33W. The ITCZ begins near 12N49W to the coast of Guyana near 08N59W. Scattered moderate convection is south of the monsoon trough from 05N-10N between 14W-30W. Scattered moderate convection is within 100 nm of the ITCZ between 49W-58W. GULF OF MEXICO... A stationary front is draped over the NW Gulf of Mexico from south- central Louisiana to the southeast Texas coast. A surface trough extends from SE Louisiana near 30N90W to 25N93W. Scattered thunderstorms are in the eastern Gulf, N of 22N and E of 89W. Winds are light across the basin. For the forecast, Tropical Depression Thirteen will move to 16.1N 50.8W Thu morning, then strengthen to a tropical storm near 17.4N 54.6W Thu evening. Thetropical storm will reach near 18.4N 58.4W Fri morning, 19.1N 62.1W Fri evening, 19.9N 65.9W Sat morning, and 20.8N 69.7W Sat evening. Thirteen will change little in intensity as it moves to near the Turks and Caicos Islands and SW Bahamas late Sun. Also, low pressure in the central Caribbean Sea tonight has a high chance of tropical formation in the next 48 hours as it reaches the NW Caribbean. This system could impact the Yucatan Channel and other portions of the central and western Gulf for the start of next week. CARIBBEAN SEA... See above discussion in Special Features for the Tropical Wave over the Caribbean. A weak pressure gradient between the Bermuda High northeast of the Caribbean and the monsoon trough in the SW Caribbean is promoting only gentle to moderate trades in the Caribbean away from the vicinity of the tropical wave. Moderate to fresh winds are noted to the east of the tropical wave, stretching from Jamaica to the eastern Caribbean. No other significant deep convection is noted in the Caribbean outside of that caused by the tropical wave. Seas range 3-6 ft with upwards of 9 ft near the low in the central Caribbean. Tropical Depression Thirteen will move to 16.1N 50.8W Thu morning, then strengthen to a tropical storm near 17.4N 54.6W Thu evening. The tropical storm will reach near 18.4N 58.4W Fri morning, 19.1N 62.1W Fri evening, 19.9N 65.9W Sat morning, and 20.8N 69.7W Sat evening. Thirteen will change little in intensity as it moves to near the Turks and Caicos Islands and SW Bahamas late Sun. Also, low pressure over the central Caribbean Sea has a high chance of tropical formation in the next 48 hours in the NW Caribbean. ATLANTIC OCEAN... See above discussion in Special Features TD Thirteen. Scattered thunderstorms are noted across the western Atlantic, N of 23N between 68W-80W. A cold front is sinking across the east-central Atlantic, stretching from 31N39W to 31N40W. No significant convection is noted with this cold front. High pressure spans across the rest of the domain anchored by a 1021 mb high near 30N51W. Moderate to fresh winds are north of Hispaniola and parts of the central Atlantic, otherwise light to gentle winds are observed across most of the basin. Farther east, fresh to strong northerly winds are off the coasts of Western Sahara and Mauritania. Seas range 4-7 ft. Tropical Depression Thirteen will move to 16.1N 50.8W Thu morning, then strengthen to a tropical storm near 17.4N 54.6W Thu evening. The tropical storm will reach near 18.4N 58.4W Fri morning, 19.1N 62.1W Fri evening, 19.9N 65.9W Sat morning, and 20.8N 69.7W Sat evening. Thirteen will change little in intensity as it moves to near the Turks and Caicos Islands and SW Bahamas late Sun. $$ AReinhart