000 AXNT20 KNHC 270554 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Fri Oct 27 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 0000 UTC surface analysis and satellite imagery through 0535 UTC. ...SPECIAL FEATURES... Storm Force Wind Warning Northwestern Atlantic (Post-Tropical Cyclone Tammy): Post-Tropical Cyclone Tammy is centered near 31.5N 60.0W at 27/0000 UTC. Estimated minimum central pressure is 980 mb. Gale to storm force winds, reaching near hurricane force closer to the center of the system N of the area, and seas of 18 to 26 ft seas are noted from 29N to 31N between 59W and 64W. Scattered moderate and isolated strong convection is noted from 20N to 31N and between 52W and 60W. This system is forecast to become separated from the front later today, and environmental conditions are forecast to become more conducive over the northwestern Atlantic to the east of Bermuda through Saturday. Regardless of tropical redevelopment, the system is likely to bring gusty winds and heavy rainfall to Bermuda during the next couple of days. Interests on Bermuda should monitor the progress of this system. This system has a medium chance of tropical cyclone formation through the next 48 hours. Please read the latest NHC Tropical Weather Outlook at www.hurricanes.gov and the latest HIGH SEAS FORECAST at www.hurricanes.gov/marine for more details. Western Atlantic Rough Seas: Swell generated from Tammy combined with swell generated from strong gradient flow that developed west of Tammy is supporting a large area of 12 ft seas over the western Atlantic waters N of 24N between 55W and 70W. Mariners should either avoid this region or use extreme caution in this area, depending on your vessel type and cargo. Hazardous surf and rip currents are also anticipated along the coast of central Florida, the Bahamas, Greater Antilles and the northern Leeward Islands. The seas of 12 ft or greater will generally continue over the waters N of 23N between 55W and 71W before subsiding this weekend. 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 Offshore Waters Forecast at https://www.nhc.noaa.gov/marine/offshores.php for more details. ...MONSOON TROUGH/ITCZ... The monsoon trough reaches the Atlantic through the coast of Senegal near 15N17W and continues to 08N25W. The ITCZ extends from 08N25W to 06N40W. Scattered moderate to isolated strong convection is observed from 04N to 09N and betwen 20W and 37W. ...GULF OF MEXICO... At the surface, a 1026 mb high pressure is centered over the Carolinas and extends southwestward into the Gulf of Mexico. In the upper levels, a broad high pressure sits over the SE Gulf helping to suppress the development of deep convection. Shallow moisture patches are seen traveling westward across the basin producing light, fast-moving showers. The pressure gradient between the ridge and lower pressures in the deep tropics support fresh to locally strong easterly winds south of 26N, along with seas of 6-9 ft. The strongest winds and highest seas are occurring north of the Yucatan Channel and off Pinar del Rio, Cuba. Mainly moderate easterly winds and seas of 3-6 ft are found in the remaining waters. For the forecast, high pressure centered north of the area will continue to support moderate to fresh winds, strong in the eastern Gulf, through the remainder of the week. Mainly gentle NE winds are expected this weekend as the pressure gradient weakens and high pressure settles over the region. The next cold front is forecast to reach the NW Gulf on Mon. This front will bring gale force winds and building seas over the western Gulf beginning on Tue. ...CARIBBEAN SEA... An upper level trough stretches across Hispaniola to Central America associated with an upper level low located east of the SE Bahamas. The favorable dynamics, together with abundant tropical moisture, support scattered showers and isolated thunderstorms in the central Caribbean and Gulf of Honduras. The east Pacific monsoon trough enters the SW Caribbean near the Nicaragua and Costa Rica border and continues to northern Colombia. Similar convection is also observed affecting this region. In the eastern Caribbean, a surface trough extends from the Leeward Islands to northern Venezuela. Scattered showers are evident within 200 nm on both sides of this trough. Dry air dominates the NW Caribbean, allowing for fairly tranquil weather conditions. A tight pressure gradient supports fresh to strong easterly winds north and east of the surface features described in the paragraph above, mainly north of 14N and west of 67W. This was also captured by a recent scatterometer satellite pass. Seas in these waters are 5-8 ft, with the highest waves occurring between the Cayman Islands and western and central Cuba. Moderate or weaker winds and 3-6 seas prevail elsewhere. However, seas to 7 ft are present in the water passages in the NE Caribbean due to the large swell region associated with the strong extratropical cyclone located southeast of Bermuda, the remnants of Tammy. For the forecast, strong high pressure N of the area will continue to support fresh to occasionally strong NE to E winds in the NW and north- central Caribbean, including the Windward Passage through the week. Gentle winds are expected elsewhere. ...ATLANTIC OCEAN... Please read the Special Features section above for more on a Storm Warning associated with Post-Tropical Cyclone Tammy southeast of Bermuda, and rough seas across the SW tropical Atlantic. The remainder of the tropical Atlantic is dominated by a subtropical ridge located near the Azores. A surface trough in the eastern Caribbean is also generating an area of showers and isolated thunderstorms to the east of the Lesser Antilles. Farther east, an upper level trough is producing showers and thunderstorms from 05N to 16N and between 40W and 50W. The pressure gradient between the ridge and lower pressures in the deep tropics support fresh to locally strong easterly winds and seas of 6-8 ft south of 14N and between 30W and 50W. A similar pattern sustains fresh to locally strong NE winds off western Africa, mainly from 15N to 24N and east of 30W. Seas in these waters are 6-8 ft. Elsewhere, moderate or weaker winds and moderate seas prevail. For the forecast W of 55W, a strong extratropical cyclone, former Tammy, associated with an occluded front is located near 31.5N60W. This system is forecast to become separated from the front during the next day or so, and environmental conditions are forecast to become more conducive for the low to regain tropical characteristics while it meanders over the northwestern Atlantic to the east of Bermuda through Saturday. Currently, high winds and hazardous seas are still present, and a Storm Warning remains in effect for portions of the area SE of Bermuda. Gales will continue into Fri. The gradient between this low and high pressure N of the area will continue to support strong to near gale-fore NE winds and very rough seas well W of the low across much of the forecast area through the week. $$ DELGADO