000 AXNT20 KNHC 271020 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 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 0600 UTC surface analysis and satellite imagery through 1000 UTC. ...SPECIAL FEATURES... Gale Warning Northwestern Atlantic (Post-Tropical Cyclone Tammy): A strong sub-tropical low is centered N of the area near 31.7N60.8W at 27/0600 UTC. An occluded front extends from the low to 35N53W then a stationary front extends from that point to 23N60W. Estimated minimum central pressure is 985 mb. Gale force winds prevail N of 30N between 59W and 61W, while strong to near gale winds prevail N of 28N between 57W and 69W. Seas to 24 ft are noted within the area of Gale force winds. These wind conditions will diminish this morning, but long period swell will continue moving across the Atlantic waters through the weekend. Scattered moderate and isolated strong convection is noted within 60 nm of the low and fronts. This system is forecast to become separated from the fronts 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 the low described above combined with swell generated from strong gradient flow that developed west of the low is supporting a large area of 12 ft seas over the western Atlantic waters N of 23N between 59W and 74W. 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 area 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 10N23W. The ITCZ extends from 10N23W to 07N39W. Scattered moderate to isolated strong convection is observed from 05N to 10N and betwen 25W and 43W. ...GULF OF MEXICO... Surface ridging prevails across the basin, anchored by a 1025 mb high centered over the Carolinas. 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 strong easterly winds south of 25N, 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. Moderate easterly winds and seas of 3-6 ft prevail elsewhere. 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 and east Caribbean. 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 along 65W with scattered showers. 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 15N and west of 68W. 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. For the forecast, strong high pressure N of the area will continue to support fresh to 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 information on the Gale Warning associated with the strong sub- tropical low 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 north 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 strong easterly winds and seas of 6-8 ft south of 14N and between 36W and 50W. A similar pattern sustains fresh to locally strong NE winds off western Africa, mainly from 16N to 23N and east of 28W. Seas in these waters are 6-8 ft. Elsewhere, moderate or weaker winds and moderate seas prevail. For the forecast W of 55W, the strong extratropical cyclone is forecast to become separated from the front today, and environmental conditions are forecast to become more conducive over the northwestern Atlantic to the east of Bermuda through Saturday. Currently, high winds and hazardous seas are still present, and a Gale Warning remains in effect for portions of the area SE of Bermuda through this morning. 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. $$ ERA