735 AXNT20 KNHC 181048 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Sat Sep 18 2021 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 31N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 0600 UTC surface analysis and satellite imagery through 1030 UTC. ...SPECIAL FEATURES... Tropical Storm Odette is centered near 38.0N 69.3W at 18/0900 UTC or 200 nm S of Nantucket Massachusetts moving NE at 13 kt. Estimated minimum central pressure is 1008 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Seas are peaking at 12 to 13 ft near and up to 90 nm in a semicircle N of the center. Odette remains highly sheared, with an exposed and elongated center. Numerous moderate to isolated strong convection is noted well NE of the center from 36N to 40N between 63W and 67W. Odette is expected to continue a NE track with little change in speed through Sunday. This will take Odette south of the northeast U.S. and Atlantic Canada coasts over the weekend. Odette is forecast to maintain its current intensity while transitioning into an extra- tropical storm through tonight. Afterward, gradual strengthening is likely and Odette will become a strong extratropical storm on Sunday. Please read the latest NHC Public Advisory at https://www.nhc.noaa.gov/text/MIATCPAT5.shtml for more information. The Atlantic Offshore Waters Forecast issued by OPC can be found at https://www.ocean.weather.gov/offshore/indexphp?basin=atl&type=offshore#close Atlantic gale warning: Low pressure near 14N49W centered in the tropical Atlantic is becoming a little better organized. There has been considerable easterly shear across this low, keeping convection fairly weak. However, as the low moves into a more favorable environment on the southeast side of an upper low, the convection is increasing and a band is forming on the north side of the. There is a high chance this low will become a tropical depression in the next 48 hours. While a scatterometer pass from late yesterday evening did not conclusively show this low was closed off, it did show strong winds on its north side, between the low and high pressure north of the area. These winds may increase as the low deepens today, and a gale warning has been issued accordingly, which may be changed to a tropical storm warning if the low continues to be become better organized. The window for that to happen is fairly small, as the low will enter a less favorable environment relative to the upper trough heading into mid week when the low reaches a position to the northeast of the Leeward Islands. Regardless of development, increased winds, seas, and convection is likely within 120 to 180 nm mainly on the north side of the low over the next couple of days. Refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. ...TROPICAL WAVES... An Atlantic tropical wave is along 24W from 19N southward through the Cabo Verde Islands and a 1008 mb low pressure near 09N25W, and moving W near 10 kt. Scattered moderate to isolated strong convection is found from 04N to 09N between 23W and 33W. The system has a low chance of formation within the next 48 hours. Refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. Another Atlantic tropical wave is near 50W/51W from 19N southward through a 1009 mb low pressure, and moving W near 15 kt. Scattered moderate to isolated strong convection is present from 14N to 18N between 45W and 53W. See the Special Features section above for potential development of this system. A W Caribbean tropical wave is in the Gulf of Honduras along 87W from 18N southward across Honduras, Nicaragua and Costa Rica to the E Pacific Ocean, and moving W near 10 kt. No significant showers or thunderstorms are noted in the Caribbean related to this tropical wave. ...MONSOON TROUGH/ITCZ... A monsoon trough extends across the African coast near the Mauritania-Senegal border at 17N16W through the 1008 mb low mentioned in the Tropical Waves section above to 12N37W. No ITCZ is present based on the latest analysis. A few showers are possibly ongoing off Dakar, Senegal. Elsewhere, no significant convection is noted other that what is described in the Tropical Wave section above. The E end of the E Pacific monsoon trough is triggering scattered showers and thunderstorms near the Panama-Colombia border. ...GULF OF MEXICO... Scattered showers and a few thunderstorms are active over the loop current in the central Gulf, on the southeast side of a short wave trough digging through the northwest Gulf. Gentle to moderate breezes and slight seas are noted across the basin. For the forecast, weak high pressure will extend across the eastern and central Gulf of Mexico through early next week. This pattern will support continued gentle to moderate winds and mostly slight seas across the Gulf through the next several days. Looking ahead, a weak cold front may move into the northwest and north- central Gulf by mid week. ...CARIBBEAN SEA... The Atlantic ridge north of the basin is maintaining fresh to strong trade winds over the south- central Caribbean, particularly off Colombia. A recent altimeter satellite pass indicated seas to 8 ft about 120 nm northwest of Cartagena. Fresh to strong E winds were noted in the Gulf of Honduras by an earlier scatterometer satellite pass. Mostly moderate winds and sea persist elsewhere. A few showers and thunderstorms are active off the southern peninsula of Haiti, as well as from western Panama to southeast Nicaragua. For the forecast, the Atlantic ridge will shift westward through Sun, as Tropical Storm Odette, off the middle Atlantic coast, lifts northward. This will support fresh to strong winds over the south- central Caribbean and Gulf of Honduras into early Sun. The ridge will weaken starting Sun night as a tropical wave and area of low pressure currently across the central Atlantic move to the northeast of the Leeward Islands early Mon, then begin to move more NW. There is a high chance this low pressure will form into a tropical cyclone over the next several days. Regardless of further development, expect increase winds, seas and thunderstorms north through east of the Leewards early next week. ...ATLANTIC OCEAN... Please see the Special Features section above for potential tropical development in the Atlantic Basin. A mid to upper- level trough near 29N50W continues to trigger scattered moderate convection from 25N to 31N between 46W and 50W. Locally fresh winds and seas up to 6 ft are possible near this convection. Refer to the Tropical Waves and Monsoon Trough/ITCZ sections for additional convection across the basin. An expansive surface ridge extends southwestward from a 1026 mb Azores high across S of Bermuda to Florida. This feature is providing gentle to moderate winds with seas at 3 to 5 ft north of 25N west of 35W. Other than the fresh winds and higher seas mentioned near the 1008 mb low in the Special Features section, gentle to moderate winds and seas of 3 to 5 ft are seen N of between 10N and 26N between 50W and the S Florida Coast and the Lesser Antilles. Moderate to locally fresh NE trades and seas at 6 to 8 ft are evident N of 27N between the African coast and 35W. Gentle to locally moderate winds and seas of 4 to 6 ft prevail across the rest of the basin. For the forecast west of 65W, weak ridging through the N Bahamas will support mostly light breezes and slight seas north of 22N through early next week, and moderate trade winds and moderate seas south of 22N at least through Sun. Meanwhile, an area of low pressure currently well to the SE over the central tropical Atlantic will approach the waters NE of the Leeward Islands Sun and Mon, then begin to move more NW over open Atlantic waters. There is a high chance this low pressure will form into a tropical cyclone over the next several days. Regardless of further development, expect increase winds, seas and thunderstorms N through E of the Leewards Islands and NE of Puerto Rico early next week. $$ Christensen