000 AXNT20 KNHC 101040 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Fri Sep 10 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... Hurricane Larry is centered near 37.7N 61.8W at 10/0900 UTC or 360 nm NNE of Bermuda moving NNE at 23 kt. Estimated minimum central pressure is 968 mb. Maximum sustained wind speed is 75 kt with gusts to 90 kt. Numerous moderate to strong convection is noted within 250 nm of the center in the southern semicircle and 200 nm in the northern semicircle. On the forecast track, Larry is expected to turn to the northeast with a further increase in forward speed is expected today. The center of Larry will pass well southeast of Nova Scotia today, and move over southeastern Newfoundland tonight. Gradual weakening is forecast during the next day or so, but Larry is expected to remain a hurricane until it passes Newfoundland. Larry should become an extratropical cyclone on Saturday, and is now forecast to be absorbed by a larger extratropical low near Greenland by the end of the weekend. Swells generated by Larry will continue to affect the Bahamas today. Significant swells from Larry will continue affecting Bermuda, the east coast of the United States, and Atlantic Canada through Saturday. These swells are likely to cause life- threatening surf and rip current conditions. Please read the latest High Seas Forecast issued by the National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. A strong tropical wave is expected to emerge off of the west coast of Africa later today or tonight. Environmental conditions are forecast to be conducive for development thereafter, and a tropical depression is likely to form by early next week as the system moves west-northwestward over the far eastern Atlantic near the Cabo Verde Islands. Interests in the Cabo Verde Islands should monitor the progress of this system. The disturbance has a medium chance of development over the next 48 hours and a high chance of development over the next 5 days. Please see the latest Tropical Weather Outlook from the National Hurricane Center. ...TROPICAL WAVES... An Atlantic tropical wave has an axis along 35W south of 21N, moving W at 15-20 kt. No significant convection is noted with this wave at this time. An Atlantic tropical wave has an axis along 49W south of 21N, moving W at 10-15 kt. No significant convection is noted with this wave at this time. A Caribbean tropical wave has an axis long 72W from 18N southward, moving W at 10-15 kt. This wave has isolated thunderstorms within 60 nm of the axis especially near the Hispaniola coast. A Caribbean tropical wave has an axis along 88W from 20N southward, moving W around 10 kt. Scattered moderate to isolated strong convection is noted in the Gulf of Honduras and the NW Caribbean from 13N to 21N between 82W and 88W. This system is forecast to move into the Bay of Campeche and merge with a pre- existing surface trough located over the southwestern Gulf of Mexico by this weekend. Environmental conditions are expected to be conducive to support gradual development, and a tropical depression could form Sunday or Monday before the system moves onshore along the western Gulf of Mexico coast. For more details, please read the latest Tropical Weather Outlook from the National Hurricane Center. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the Guinea-Bissau cost near 12N16W to 06N23W to 10N42W. No ITCZ segment is analyzed. Scattered moderate to isolated strong convection is noted along and south of the monsoon trough from 03N to 11N between 11W and 24W. Isolated thunderstorms are also noted from 03N to 07N between 29W and 33W. ...GULF OF MEXICO... At 0900 UTC, a cold front extended off of the Florida Big Bend near 30N83W to the Middle Texas coast near 28N96W. Isolated showers and thunderstorms are noted within 90 nm of the front. Moderate north-northeast winds are north of the front with light to gentle winds elsewhere across the basin. A trough extends across the western Gulf from 27N95W to 19N93W. Scattered moderate to isolated strong convection is noted near and east of this trough from 18N to 26N between 85W to 97W. Thunderstorms are also occurring on the bay side of the Florida Keys. Seas are 1 to 3 ft across the Gulf. For the forecast, the northern portion of a tropical wave is producing disorganized showers and thunderstorms over the NW Caribbean. This system is forecast to move into the Bay of Campeche and merge with a pre- existing surface trough located over the southwestern Gulf of Mexico by this weekend. Environmental conditions are expected to be conducive to support gradual development, and a tropical depression could form Sunday or Monday before the system moves onshore along the western Gulf of Mexico coast. This system has a low chance of development in 48 hours and medium chance in the next 5 days. Regardless of development, this system could bring an increase in winds and seas across the Gulf waters during the upcoming weekend. Meanwhile, a frontal boundary over the northern Gulf will continue through Sun will bring showers and thunderstorms across the region. ...CARIBBEAN SEA... Please see the Tropical Waves section for details on the tropical waves moving across the area. Outside of the convection associated with the tropical wave near the Gulf of Honduras, most of the Caribbean Sea is dominated by dry weather conditions. Scattered thunderstorms are noted in the SW Caribbean near the monsoon trough, S of 12N between 77W and 83W. Overnight scatterometer satellite pass depict strong to locally near gale- force trades in the south- central Caribbean, especially within 150 nm of the NW coast of Colombia. Moderate to fresh trades are found in the north- central Caribbean, E Caribbean and NW Caribbean, while gentle to moderate trades are noted in the SW Caribbean. Seas of 6-9 ft are prevalent in the south-central Caribbean and 3-6 ft elsewhere in the basin. For the forecast, the Atlantic ridge will build westward across the Caribbean Sea bringing an increase in the trade wind flow through the weekend. Fresh to strong winds will occur offshore Colombia and in the Gulf of Venezuela, mainly at night through Sat night. Fresh to strong winds are also likely in the late evening in the Gulf of Honduras Friday and Saturday. Scattered showers and thunderstorms are expected to continue across the NW Caribbean today and reduce in coverage by Sat. ...ATLANTIC OCEAN... Please see the Special Features section above for details on Hurricane Larry over the NW Atlantic. Scattered moderate convection is occurring in the SW N Atlantic ahead of a sinking cold front, N of 26N between 71W and 79W. Otherwise, the 1024 mb subtropical ridge is beginning to re- assert dominance over the tropical Atlantic as Hurricane Larry continues to move away. Fresh to strong cyclonic winds associated with the circulations of Post-Tropical Cyclone Mindy are noted north of 29N between 71W and 75W. Seas in this area are 8-11 ft. Winds in the wake of Larry are moderate to locally fresh with seas to 10 ft. Larger swells traveling farther away from Larry are generating seas of 5-8 ft N of 23N between 69W and the Florida- Georgia coast, including the Bahamas. Otherwise, high pressure dominates the central and eastern Atlantic. A tight pressure gradient over the NE Atlantic results in fresh to strong NE winds within 180 nm of the coasts of Morocco and Western Sahara, and the waters surrounding the Canary Islands. Seas in this region are 7-10 ft. Gentle to moderate easterlies prevail across the rest of the basin with seas of 4-7 ft. For the forecast, fresh to strong winds from Post-Tropical Cyclone Mindy are expected to move north of the forecast waters by this morning. Seas associated with Mindy will subside by tonight. Swells generated by Hurricane Larry will also subside by tonight. A frontal boundary will linger across the SW N Atlantic through Sun which will bring showers and thunderstorms across the area during the weekend. $$ AReinhart