000 AXNT20 KNHC 131731 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Sun Sep 13 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 1200 UTC surface analysis and satellite imagery through 1700 UTC. ...SPECIAL FEATURES... ...T.S. SALLY... Tropical Storm Sally is centered near 27.5N 84.9W at 13/1500 UTC or 115 nm W of St. Petersburg Florida moving WNW at 10 kt. Estimated minimum central pressure is 998 mb. Maximum sustained wind speed is 50 kt with gusts to 60 kt. Numerous moderate scattered strong convection is noted within 120 nm of the center in the NE quadrant and 210 nm SE quad. Scattered moderate isolated strong convection is elsewhere within 150 nm NE quad and 240 nm SE quad. The center of Sally will move over the north-central Gulf of Mexico tonight and Monday, then turn to the north-northwest Monday night as it approaches the north- central Gulf Coast within the Hurricane Warning area. Sally is expected to move farther inland over southeastern Louisiana Tuesday and Tuesday night. Further strengthening is expected over the next day or so, and Sally is forecast to become a hurricane on Monday, with some additional strengthening possible before landfall Monday night. A dangerous storm surge is expected for coastal portions of southeastern Louisiana and Mississippi, where a Storm Surge Warning is in effect. Sally is expected to be a slow moving system resulting in significant flash flooding due to very heavy rainfall for the central Gulf Coast Monday through the middle of the week. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT4.shtml and Forecast/Advisory at https://www.nhc.noaa.gov/text/MIATCMAT4.shtml for more details. ...HURRICANE PAULETTE... Hurricane Paulette is centered near 29.9N 61.9W at 13/1500 UTC or 210 nm SE of Bermuda moving NW at 12 kt. Estimated minimum central pressure is 976 mb. Maximum sustained wind speed is 70 kt with gusts to 85 kt. Scattered moderate isolated strong convection is noted within 150 nm of the center in the northern semicircle and SW quadrant, and within 60 nm SE quad. The center of Paulette will move near or over Bermuda Monday morning. Strengthening is forecast, and Paulette is expected to be a dangerous hurricane when it approaches Bermuda late tonight and early Monday. Some further strengthening is possible when Paulette turns northeastward and moves away from Bermuda late Monday through Tuesday. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT2.shtml and Forecast/Advisory at https://www.nhc.noaa.gov/text/MIATCMAT2.shtml for more details. ...T.D. RENE... Tropical Depression Rene is centered near 26.8N 47.6W at 13/1500 UTC or 1000 nm NE of the northern Leeward Islands moving NW at 8 kt. Estimated minimum central pressure is 1011 mb. Maximum sustained wind speed is 25 kt with gusts to 35 kt. Isolated moderate to strong convection is noted within 120 nm of the center in the eastern semicircle. Rene is forecast to continue weakening and become a remnant low on Monday. 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/MIATCMAT3.shtml for more details. ...T.D. TWENTY... Tropical Depression Twenty is centered near 12.3N 36.4W at 13/1500 UTC or 755 nm WSW of the Cabo Verde Islands moving WNW at 9 kt. Estimated minimum central pressure is 1006 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. Scattered moderate isolated strong convection extends out 270 nm from the center in the southern semicircle and 180 nm NW quadrant. A motion to the west or west-northwest is expected to continue through Tuesday, followed by a turn to the northwest Tuesday night or Wednesday. Strengthening is expected, and the system is forecast to become a hurricane on Tuesday. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT5.shtml and Forecast/ Advisory at https://www.nhc.noaa.gov/text/MIATCMAT5.shtml for more details. ...EASTERN ATLANTIC LOW PRESSURE... A 1009 mb low along a tropical wave is located near 17N27W, or about 100 nm west of the westernmost Cabo Verde Islands. The low is moving to the WNW at 10 kt. Scattered moderate convection is from 13N-20N between 23W-31W. Although the low's circulation appears somewhat elongated, the associated shower and thunderstorm activity is showing some signs of organization. Environmental conditions are expected to be conducive for additional development during the next day or so while the system moves toward the NNW at 5 to 10 kt, and a tropical depression is likely to form before it moves over colder waters and into an area of strong upper-level winds by Tuesday. This system has a high chance of tropical cyclone formation during the next 48 hours. Please refer to the latest Tropical Weather Outlook at www.nhc.noaa.gov/gtwo.php?basin=atlc&fdays=2 for more details. ...TROPICAL WAVES... A tropical wave along 27W is discussed in the Special Features section above. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Africa near 16N17W to a 1009 mb low near 17N27W to 15N32W. The monsoon trough continues from 10N40W to 09N43W to 11N49W. Aside from the convection mentioned above in the Special Features section, scattered moderate isolated strong convection is from 06N-13N between 40W-46W. GULF OF MEXICO... Tropical Storm Sally, located over the eastern Gulf of Mexico, is currently producing seas to 14 ft near its center. Peak seas associated with Sally are forecast to increase to near 24 ft by Monday morning as it strengthens to a hurricane over the north central Gulf of Mexico. Please see the Special Features section above for more details on Tropical Storm Sally. Elsewhere, a 1008 mb low near 25N93W is along a surface trough that extends from 27N95W to 22N89W. Scattered showers and tstorms cover much of the western Gulf of Mexico west of 92W. A recent ASCAT pass shows moderate winds across the western half of the Gulf of Mexico, with fresh NE winds north of 28N near the coast of Louisiana. Tropical Storm Sally is forecast to strengthen to a hurricane near 28.5N 88W Mon morning, then move inland to near 30N90W Tue morning and weaken to a tropical storm near 30.3N 90.5W Tue evening. Sally will be near 31.5N 90W Wed morning, then weaken to a tropical depression over Mississippi early Thu. Elsewhere, the surface trough over the western Gulf of Mexico will move southwest through mid-week, with a low chance of tropical cyclone formation. CARIBBEAN SEA... Scattered showers and tstorms seen over western Cuba are more due to the daytime heating than to Tropical Storm Sally, which is located well north of the basin over the northeastern Gulf of Mexico. The east Pacific monsoon trough is producing scattered strong convection over the SW Caribbean south of 14N. This convection is being enhanced by an upper-level low over the SW Caribbean. A recent ASCAT pass shows gentle to moderate trade winds across the basin. Moderate trade winds will prevail in the central and eastern Caribbean through late Tue. Surface ridging will establish over the SW Atlantic waters by mid-week, resulting in moderate to fresh trades in the central and eastern Caribbean. Moderate southeast winds are expected to continue in the NW basin through Tue. No tropical cyclones are expected over the Caribbean Sea during the next 5 days. ATLANTIC OCEAN... Please see the Special Features section above for more details on Hurricane Paulette, Tropical Depression Rene, Tropical Depression Twenty, and the 1009 mb low west of the Cabo Verde Islands. Scattered gusty showers and tstorms are currently seen within 60 nm of the east coasts of Florida and Georgia. This activity is associated with the outermost rains of Tropical Storm Sally, which is located over the eastern Gulf of Mexico. The circulation of Sally is still producing fresh SE winds offshore of Florida, as shown by a recent ASCAT pass. Farther east, a tail of moisture extending well southwestward from Hurricane Paulette is enhancing scattered showers from the SW Bahamas to 27N between 66W-73W. However, winds in that area are gentle. Hurricane Paulette will move to near 33N65W Mon morning, 37N60W Tue morning, and 41N49W Wed morning. Large swell associated with Paulette will spread westward across the offshore waters and continue to build seas early this week. Tropical Depression Twenty will strengthen to a tropical storm near 13N38W this evening, then strengthen to a hurricane near 14.5N 45W Tue morning, then move to near 16N48W Wed morning and 19N51W Thu morning. $$ Hagen