000 AXNT20 KNHC 222336 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Mon Oct 23 2023 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 2330 UTC. ...SPECIAL FEATURES... Hurricane Tammy is centered near 19.9N 63.4W at 22/2100 UTC or 100 nm N of Anguilla, moving NW at 8 kt. Estimated minimum central pressure is 988 mb. Maximum sustained wind speed is 75 kt with gusts to 90 kt. Peak seas are around 27 ft with the 12 ft seas extending 180 nm in the northern semicircle, 150 nm in the SE quadrant and 60 nm in the SW quadrant. Numerous moderate to strong convection is noted from 18N to 23N between 60W and 66W. Tammy is expected to turn toward the north is expected late tonight, followed by a north- northeast or northeast motion on Monday and Tuesday. Some slight strengthening is possible during the next few days. Tammy is still expected to produce heavy rainfall across the Leeward Islands and the US and British Virgin Islands. These rains may produce isolated flash and urban flooding, along with isolated mudslides in areas of higher terrain. Swells generated by Tammy will continue to affect portions of the Lesser Antilles during the next few days. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office and read the latest HIGH SEAS FORECAST issued by National Hurricane Center at web-site https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest Hurricane Tammy Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Southwestern Caribbean Sea (AL95): Showers and thunderstorms have changed little in organization since this morning in association with a low pressure system located over the southwestern Caribbean Sea. However, environmental conditions are favorable for development, and a tropical depression could form before the system moves inland over Nicaragua by early Tuesday. Regardless of development, this system could produce heavy rains over portions of Central America during the next couple of days. The latest Tropical Weather Outlook gives this system a medium chance of tropical cyclone development through 48 hours, and also through 7 days. Refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. Gale Warning E of 35W: A 989 mb low pressure located over the eastern Atlantic near 36N09W continues to support gale force winds over the marine zones called Madeira and Agadir in the Meteo- France High Seas Forecast area. For more details, refer to the Meteo-France High Seas Forecast listed on their website https://wwmiws.wmo.int ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the coast of Senegal near 12N16W to 10N22W. The ITCZ extends from 10N22W to 10N51W. Scattered moderate convection is noted from 04N to 12N between 18W and 51W. A surface trough extends beyond the ITCZ from 16N56W to 10N57W with scattered moderate isolated strong convection from 07N to 18N between 52W and 59W. ...GULF OF MEXICO... High pressure of 1017 mb centered over the NE Gulf near 29N88W dominates most of the basin producing mainly light to gentle anticyclonic flow and seas of 1 to 2 ft, with the exception of gentle to moderate southerly return flow and seas of 2 to 4 ft W of 94W. Narrow lines of low-level clouds are moving N over the western Gulf under the influence of the southerly flow. For the forecast, a weak cold front will move into the eastern Gulf tonight then dissipate through early Mon over the southeast Gulf. High pressure will build toward the region from the north in the wake of the front, leading to increasing E winds. Fresh to locally strong winds and building seas are expected Mon into Thu over the northern Gulf and through Fri over the southern Gulf. ...CARIBBEAN SEA... Please read the SPECIAL FEATURES section for details about Hurricane Tammy and Invest AL95. A surface trough extends from west of the Cayman Islands to a 1007 mb low pressure centered near 11.5N82W. Numerous showers, with embedded thunderstorms are around the low pressure from 11N to 15N between 80W and 84W. Moderate to fresh winds are noted around this low. An outer rain band of Hurricane Tammy continues to impact the Lesser Antilles and the eastern Caribbean N of 15N and E of 65W. Outside of Tammy, gentle to moderate N to NE winds are W of the above mentioned trough, with light to gentle winds in the central and eastern Caribbean. Seas are 4 to 6 ft in the NE Caribbean, 3 to 5 ft over the eastern Caribbean, and 2 to 4 ft elsewhere. For the forecast, Hurricane Tammy is about 105 nm N of Anguilla Island, near 19.9N 63.4W at 5 PM EDT, and is moving northwest at 8 kt. Maximum sustained winds are 75 kt with gusts to 90 kt, and the minimum central pressure is 988 mb. Tammy will move to 20.9N 63.8W Mon morning,, then continue to move north of the region through mid week. Meanwhile, showers and thunderstorms continue to become better organized in association with a low pressure system located over the southwestern Caribbean Sea around 60 nm of Providencia Island. Gradual development of this system is possible, and a tropical depression could form before the system moves inland over Nicaragua by early Tue. ...ATLANTIC OCEAN... Please read the SPECIAL FEATURES section for details about Hurricane Tammy as well as gale conditions in the far eastern Atlantic. A stationary front extends from 31N61W across the southern Bahamas to the coast of central Cuba near 22N77W. A band of showers with isolated thunderstorms is within 60 nm of the front. Gentle to moderate winds follow the front with seas of 6 to 9 ft. In the tropical Atlantic, a surface trough extends beyond the ITCZ from 16N56W to 10N57W with scattered moderate isolated strong convection from 07N to 18N between 52W and 59W. An area of fresh winds persists near the northern end of the trough. Seas of 7 to 9 ft are noted within these winds. In the east Atlantic, a cold front extends from the coast of Mauritania near 21N17W to 21N30W to 27.5N43W. A band of mainly low clouds and possible showers is associated with the front. Moderate northerly winds are observed in the wake of the front, increasing to locally fresh between the Canary and the Madeira Islands. Seas behind the front increase rapidly due to swell generated from gale conditions to the north. Seas greater than 12 ft are currently reaching the Canary Islands. Seas of 8 to 12 ft dominate most of the waters N of 24N and E of 22W. For the forecast, Hurricane Tammy is near 19.9N 63.4W at 5 PM EDT, and is moving northwest at 8 kt. Maximum sustained winds are 75 kt with gusts to 90 kt, and the minimum central pressure is 988 mb. Tammy will move to 20.9N 63.8W Mon morning, 22.0N 63.6W Mon afternoon, 22.8N 62.9W Tue morning, 23.6N 62.0W Tue afternoon, 24.4N 61.0W Wed morning, and 25.8N 60.2W Wed afternoon. Tammy will weaken as an extratropical cyclone over 28.9N 60.4W Thu afternoon. Farther west, a stationary front stretches from 31N61W to central Cuba. A second cold front will move off Florida tonight, then dissipate as it moves eastward across the northern portions of the waters early this week. Looking ahead, high pressure building in the wake of the front combined with the impacts of Hurricane Tammy will bring an increase in winds and seas across the forecast area Mon night through Fri. $$ AReinhart