000 AXNT20 KNHC 231758 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 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 1200 UTC surface analysis and satellite imagery through 1630 UTC. ...SPECIAL FEATURES... Hurricane Tammy: Hurricane Tammy is centered near 21.9N 63.9W at 23/1500 UTC or 225 nm N of Anguilla, and moving N at 6 kt. Estimated minimum central pressure is 993 mb. Maximum sustained winds are 70 kt with gusts to 85 kt. Seas are peaking at 22 to 23 ft near the center. Numerous moderate to isolated strong convection is seen near and up to 100 nm in a NE semicircle from the center. A turn toward the NE is expected to begin later today with a slight increase in forward speed by Tue. Some modest strengthening is anticipated for the next couple of days. Please read the latest HIGH SEAS FORECAST issued by the National Hurricane Center, at the website - https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml, and the latest Tammy NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov, for more details. Southwestern Caribbean Low Pressure (Invest-AL95): A 1006 mb low pressure centered near 11N82W is producing numerous moderate to isolated strong convection from 11N to 13N between the Nicaragua cost and 81W. Scattered moderate convection is found farther north from 13N to 15W betwen the northern Nicaragua coast and 80W. Fresh to locally strong winds and seas of 4 to 6 ft are present in these areas. The showers and thunderstorms continue to show signs of organization, and environmental conditions appear to be favorable for development. A short-lived tropical depression could form before the system moves inland over Nicaragua by early Tue. Regardless of development, this system could produce heavy rains over portions of Central America during the next couple of days. There is a medium chance of tropical formation within the next 48 hours. Please refer to the latest NHC Tropical Weather Outlook, at www.hurricanes.gov, for more details. ...MONSOON TROUGH/ITCZ... A monsoon trough enters the Atlantic along the Guinea coast just north of Conakry, then curves west-southwestward to near 08N25W. Farther west, an ITCZ extends westward from 08N39W to 08N54W. Scattered moderate convection is noted near the trough from 03N to 12N between the Guinea-Liberia coast and 24W, and up to 160 nm north and 100 nm south of the ITCZ. ...GULF OF MEXICO... A very weak cold front stretches west-northwestward from near Tampa, Florida to near New Orleans, Louisiana. There is no significant convection related to this feature. A broad surface ridge dominates the rest of the Gulf, converging southeasterly winds are causing scattered showers at the SW Gulf, including the Bay of Campeche. Moderate to fresh SE winds and seas of 4 to 6 ft seas are seen at the NW Gulf, while gentle to moderate E to SE winds and 2 to 4 ft seas are evident for the remainder of the Gulf. For the forecast, the weak cold front will slide eastward and dissipate later today. High pressure will build southward in its wake. This will lead to increasing winds early this week, with fresh to locally strong E winds and building seas Mon night through Thu night. ...CARIBBEAN SEA... Please read the Special Features section above for details on a low pressure (Invest AL95) in the far southwestern basin that has the potential to become a tropical depression within the next 48 hours. A surface trough is triggering scattered showers and isolated thunderstorms in the northwestern basin just south of the Yucatan Channel and north of the Cayman Islands. Converging southerly winds feeding toward Hurricane Tammy well northeast of Puerto Rico are generating similar convection over the northern Leeward Islands. Other than the area near AL95, gentle to moderate E to SSW winds and seas of 2 to 4 ft are noted south of 17N and east of 82W. Moderate to fresh ENE to SSW winds and 4 to 6 ft seas prevail for the rest of the basin. For the forecast, Hurricane Tammy will move northward and farther away from the area today, with impacts from the system decreasing over the forecast area. Invest AL95 will maintain fresh to locally strong winds and higher seas at the far southwestern basin through Tue. ...ATLANTIC OCEAN... Please read the Special Features section at the beginning about Hurricane Tammy. A weak cold front curves west-southwestward from near Bermuda across 31N66W to near Melbourne, Florida. No significant convection is found near the front. A stationary front extends southwestward from east of Bermuda across 31N62W and the southeast Bahamas to the eastern end of Cuba. Scattered moderate convection is noted near and south of this feature from 24N to beyond 31N between 59W and 67W. Aided by divergent flow south of an upper- level low near 20N48W, convergent easterly trades are producing widely scattered moderate convection from 11N to 16N between 41W and 53W. Refer to the Monsoon Trough/ITCZ section at the beginning for additional convection in the Atlantic Basin. A large dome of 1025 mb high near 33N34W is providing gentle to moderate NNE to E to SE winds north of 20N between the northwest Africa coast and 50W. Within this same area, large north swell is creating 6 to 9 ft seas. To the west near the stationary front but outside the direct impact of Hurricane Tammy, gentle to moderate with locally fresh E to S winds and seas of 5 to 8 ft are evident north of 20N between 50W and 65W. Farther west, gentle to moderate NE winds and 4 to 6 ft seas are found from the Bahamas northward west of 65W. From 10N to 20N, moderate to fresh ENE to SE winds and seas at 5 to 7 ft exist between 40W and the Lesser Antilles. Near the Cabo Verde Islands, gentle to moderate NNE to ENE winds and 4 to 7 ft seas are present from 08N to 20N between the central Africa coast and 40W. Light to gentle with locally moderate monsoonal and southerly winds and seas at 4 to 6 ft prevail elsewhere in the Atlantic Basin. For the forecast W of 55W, Hurricane Tammy will move to 22.7N 63.4W this evening, 23.6N 62.4W Tue morning, and near 24.5N 61.2W Tue evening. By Wed morning, it will be near 25.8N 59.9W, then 27.3N 58.9W Wed evening, and weaken as an extratropical cyclone near 29.1N 58.6W Thu morning. Tammy will change little in intensity as it moves to near 31.2N 60.2W early Fri. The stationary front mentioned earlier will remain in place this week. High pressure will move off the east coast of the United States later tonight, and build north of the forecast area through midweek. The pressure gradient between the front, Tammy, and the area of building high pressure will tighten. This will help to develop of a broad area of strong NE winds and rough seas across much of the area west of the boundary starting tonight and continuing through the week. $$ Forecaster Chan