000 AXNT20 KNHC 181759 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 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 1200 UTC surface analysis and satellite imagery through 1755 UTC. ...SPECIAL FEATURES... Tropical Storm Odette is centered near 38.5N 67.3W at 18/1500 UTC or 205 nm SE of Nantucket Massachusetts moving NE at 15 kt. Estimated minimum central pressure is 1002 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 35N to 41N and between 58W and 64W. A turn toward the east-northeast at a faster forward speed is expected by this evening. Odette should then slow down and turn toward the east and southeast on Monday and Tuesday. On the forecast track, the center of Odette will pass south of Atlantic Canada Sunday and Monday. Strengthening is forecast during the next day or two, and Odette is expected to become a strong post- tropical low by tonight. 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: An Atlantic tropical wave has its axis along 51W, south of 21N, and a 1008 mb low pressure near 15N51W. The disturbance is producing a large area of showers and thunderstorms, especially over the northern semicircle, from 14N to 20N and between 48W and 54W. Recent satellite-derived wind data indicate that strong to near gale-force E winds are occurring over the NE quadrant, mainly between 15N and 18N and between 48W and 52W. The disturbance is producing seas of 7-10 ft. Only a slight increase in organization of this system would lead to the formation of a tropical depression or tropical storm, which is expected to occur later today or tonight while the low moves toward the west-northwest at about 15 mph. This system is expected to be near the northern Leeward Islands on Monday and Tuesday, and interests there should monitor its progress. Upper-level winds are likely to become less conducive for development when the system reaches the southwestern Atlantic by the early to middle part of next week. 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. Another Atlantic tropical wave has its axis along 26W, south of 19N, and a 1008 mb low pressure near 09N26W. The interaction between the disturbance and the monsoon trough results in a large area of showers and thunderstorms extending from 03N to 15N and between 20W and 37W. Recent satellite-derived wind data show fresh to strong cyclonic winds on the southern semicircle from 02N to 11N and between 20W and 35W. Environmental conditions appear conducive for further development of this system, and a tropical depression could form over the next couple of days while moving toward the northwest at 10 to 15 mph to the west of the Cabo Verde Islands. This system is expected to reach cooler waters and an area of stronger upper-level winds early next week, which could limit its development. Refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. ...TROPICAL WAVES... A tropical wave has its axis along 89W, south of 19N, extending from the peninsula of Yucatan, across Guatemala and W El Salvador, and into the E Pacific Ocean. The wave is moving W at 10 kt. No deep convection is occurring in association with this tropical wave. ...MONSOON TROUGH/ITCZ... A monsoon trough extends across the coast the Mauritania at 18N16W through the 1008 mb low mentioned in the Tropical Waves section near 09N26W to 06N37W. The ITCZ then continues from 0638W to 10N46W and then from 10N54W to the coast of Guyana near 08N59W. The shower and thunderstorm activity noted is associated with the tropical disturbances between Africa and the Lesser Antilles. Refer to the Special Section for more details. ...GULF OF MEXICO... A surface trough is analyzed from the coast of Louisiana near 30N91W to near the coast of NE Tamaulipas near 25N97W. Another surface trough is noted in the SW Gulf of Mexico from 18N94W to 24N95W. A combination of these features and upper level divergence due to a short-wave trough is allowing for scattered moderate convection from the central Bay of Campeche to the N Gulf coast, between 86W to 95W. Recent satellite-derived wind data show fresh to strong winds N 28N and between 88W and 92W, in association with the convection in the area. Moderate to locally fresh SE winds are observed in the south-central Gulf and in the E Bay of Campeche, with gentle to moderate anticyclonic winds elsewhere in the basin. Seas are 1-3 ft in the Gulf. 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 eastern extension of the E Pacific monsoon trough enters the SW Caribbean Sea near the Costa Rica and Panama border and continues to NW Colombia. A few showers are noted near the coast of NE Panama. The rest of the basin is dominated by generally dry weather conditions, suppressing the development of showers and thunderstorms. A recent scatterometer satellite pass show fresh to strong trades in the south-central Caribbean Sea, with the strongest winds occurring within 110 nm of the coast of NW Colombia. Seas in the area are 7-10 ft. Moderate to fresh trades are observed in the north-central Caribbean, with the strongest winds occurring in the Windward Passage. Seas in this region are 4-7 ft. Moderate to fresh trades are also seen in the Gulf of Honduras, with gentle to moderate trades elsewhere in the basin, and seas of 3-6 ft. 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 along 52W 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 for the information on the two disturbances in the tropical Atlantic with a chance of tropical development over the next few days. A broad 1029 mb subtropical ridge anchored near the Azores extends southwestward to the Bahamas and Florida. A weak surface trough is analyzed along 51W from 22N to 29N and it is only producing a few shallow showers near the trough axis. A few showers are also noted off the NE coast of Florida in association with convection spilling from the Gulf of Mexico. The rest of the basin enjoys fairly tranquil weather conditions. Fresh to locally strong NE winds are observed off the coast of NW Africa and the waters surrounding the Canary Islands. Fresh to strong winds are noted in recent satellite-derived wind data off the NE coast of South America with the strongest winds occurring within 140 nm of NE Brazil. Gentle to moderate anticyclonic winds in the rest of the basin. Seas in the tropical Atlantic are 3-6 ft. For the forecast west of 65W, weak ridging through the northern Bahamas will support mostly light breezes and slight seas north of 22N through early next week, and moderate to fresh trade winds and moderate seas south of 22N at least through Sun. Meanwhile, an area of low pressure currently well to the southeast over the central tropical Atlantic along 52W will approach the waters northeast 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 north through east of the Leewards Islands and northeast of Puerto Rico early next week. $$ DELGADO