000 AXNT20 KNHC 172338 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 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 1800 UTC surface analysis and satellite imagery through 2300 UTC. ...SPECIAL FEATURES... Tropical Storm Odette is centered near 36.7N 71.8W at 17/2100 UTC or 200 nm SE of Cape May New Jersey moving NE at 13 kt. Estimated minimum central pressure is 1010 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. Peak seas are near 13 ft. Numerous moderate and scattered strong convection is noted from 35N-40N between 65W- 70W. Odette is expected ton continue moving toward the northeast tonight. A turn toward the east- northeast with an increase in forward speed is expected to begin on Saturday and continue through Monday. On the forecast track, the center of Odette will move away from the U.S. Mid-Atlantic coast and pass south of Atlantic Canada over the weekend. Strengthening is forecast during the next couple of days, and Odette is expected to become a strong post-tropical low by Saturday night. 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. A tropical wave located midway between the Lesser Antilles and Cabo Verde Islands has an axis that extends from 20N47W to a 1011 mb low pressure near 13N45W to 03N45W, moving W at 15-20 kt. Scattered moderate and isolated strong convection is noted from 12N-17N between 45W-50W. Environmental conditions are expected to be conducive for further development during the next couple of days, and a tropical depression is likely to form over the weekend or early next week while moving toward the west-northwest at about 15 mph across the central tropical Atlantic and then near the northern Leeward Islands by Monday and Tuesday. Upper-level winds could become less conducive for development over the southwestern Atlantic by the early to middle part of next week. Interests in the Leeward Islands should monitor the progress of this system during the next few days. The system has a high chance of formation within the next 48 hours. Refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. ...TROPICAL WAVES... A tropical wave is along 23W from 19N southward, moving W at 15 kt. A broad 1010 mb low pressure is along the wave near 11N22W. Scattered moderate and isolated strong convection is found from 03N-13N between 20W-30W. This system is expected to move toward the west and then northwest at 5 to 10 mph over the far eastern Atlantic, and some gradual development is possible over the weekend before upper-level winds increase and the low moves over cooler waters. This system has a low chance of tropical cyclone formation within the next 48 hr. Refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. A tropical wave is along 45W. See the Special Features section for details. A western Caribbean tropical wave is near 84W from 18N southward to Honduras and Nicaragua, moving W near 15 kt. Scattered moderate is found south of 15N west of 80W. ...MONSOON TROUGH/ITCZ... The monsoon trough extends across the coast of Mauritania near 17N16W to 1010 mb low pressure near 11N22W to 12N42W. The ITCZ is from 06N46W to 05N52W. Aside from the convection mentioned in the sections above, no other deep convection is present. GULF OF MEXICO... The weak 1014 mb remnant low of Nicholas is drifting northward over NW Louisiana at 2100 UTC. A surface trough extends from the low pressure to 30N91W to 28N95W. Another surface trough extends from 30N87W to 29N84W. A mid to upper-level low centered over Texas is helping to induce scattered to numerous moderate with isolated strong convection north of 24N and east of 90W. Winds are moderate or weaker over the Gulf. Seas are 2 to 4 ft, except near 5 ft in the Yucatan Channel. 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 winds and mostly slight seas across the Gulf through the next several days. CARIBBEAN SEA... The pressure gradient from ridging north of the Caribbean to the 1010 mb Colombia low is contributing toward fresh to strong NE trades over the south-central Caribbean with moderate to fresh trades elsewhere. Seas are 6-8 ft in the south-central Caribbean and 4-6 ft elsewhere. Convection associated with a tropical wave reaching Central America is described above in the Tropical Waves section. No additional deep convection is present over the Caribbean. For the forecast, the Atlantic ridge will shift westward through Sun, as newly formed 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 and Tropical Wave section above for details on two tropical waves over the Atlantic. An expansive ridge extends ENE-WSW north of our waters along 35N-40N. A moderate pressure-gradient between the ridge and lower pressures in the monsoon trough/ITCZ is contributing toward generally moderate to fresh NE to E trades across the tropical N Atlantic. Seas are 7-9 ft from 10N-25N east of 47W and 4-6 ft elsewhere. An upper-level trough is helping to force two surface troughs: one from 25N54W northward to beyond 31N53W and another from 20N48W to 27N48W. Scattered moderate convection is present from 25N-31N between 47W-50W. 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 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 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 Puerto Rico early next week. $$ Landsea