000 AXNT20 KNHC 032335 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Mon Sep 4 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 2300 UTC. ...SPECIAL FEATURES... Tropical Storm Gert is centered near 32.8N 51.3W at 03/2100 UTC or 680 nm E of Bermuda, moving NNE at 16 kt. Estimated minimum central pressure is 999 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. Scattered moderate convection is evident within 60 nm of the center of Gert, with the center partially exposed. Seas 12 ft or greater are noted within 120 nm in the southeast semicircle of the center, and within 60 nm of the northwest semicircle. Gert continues to move to the NNE, but may turn more to the N tonight. The storm will weaken through the next 24 hours. 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 Gert NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Tropical Storm Katia is centered near 27.1N 32.9W at 03/2100 UTC or 830 nm NW of the Cabo Verde Islands, moving NW at 6 kt. Estimated minimum central pressure is 1006 mb. Maximum sustained wind speed is 35 kt with gusts to 45 kt. The center of Katia remains exposed on the latest satellite imagery, with a large convective burst in the northern semicircle noted this evening. Seas in excess of 12 ft are evident within 150 nm in the northern semicircle of Katia, and within 30 nm in the southern semicircle of the storm. Katia will weaken to a depression tonight as it moves slowly NW. 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 Katia NHC Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. Invest AL95: Showers and thunderstorms associated with a tropical wave located several hundred miles southwest of the Cabo Verde Islands have become better organized since yesterday. Environmental conditions are forecast to be conducive for further development, and this system is expected to become a tropical depression around midweek. Additional strengthening is likely late this week while the system moves westward to west-northwestward at 15 kt over the central and western portions of the tropical Atlantic. The chance of formation into a tropical cyclone during the next 48 hours is medium, but high through the next seven days. Please refer to the website: www.hurricanes.gov for more details. Large swell event: Large northerly swell with wave heights of 8 to 12 ft and 12 second periods persists over the western Atlantic north of 22N and west of 50W. This swell is the result of earlier winds associated with Idalia and Gert, and it may cause rough surf near the Bahamas this evening. The swell will decay through Mon. ...TROPICAL WAVES... An Atlantic tropical wave is along 28W from 03N to 18N, moving west at 15 kt. The Invest AL95 low pressure is centered along the tropical wave where it intersects the monsoon trough 10N28W with a pressure of 1010 mb. Scattered moderate convection is along the tropical wave axis 14N. A Caribbean Sea tropical wave is along 71W, from 19N southward, moving westward 10 knots to 15 knots. No significant convection is evident near the wave axis at this time. A Caribbean Sea tropical wave is along 82W, from 19N southward, moving westward 10 knots to 15 knots. Scattered moderate convection is evident near 11N82W. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from 12N16W to the 1010 mb low pressure near 10N28W to 11N35W. The ITCZ continues from 11N35W to 12N40W to 09N53W. Aside from the convection already mentioned tropical waves section, scattered moderate convection from 08N to 11N between 50W and 55W. ...GULF OF MEXICO... A weak cold front extends from western Cuba to southeast Louisiana, and high pressure dominates the western Gulf. Moderate winds and 2 to 4 ft are noted east of the front, and gentle winds and 1 to 3 ft seas are evident elsewhere. For the forecast, high pressure over the southeastern United States will support gentle to moderate E to SE winds across the basin north of 22N through mid- week. Dissipating high pressure will lead to a weaker pressure gradient afterward, thus resulting in light to gentle variable winds the remainder forecast period. ...CARIBBEAN SEA... Moderate to fresh SE winds and 4 to 6 ft seas are evident over the eastern Caribbean following the tropical wave over the central part of the basin. Gentle winds and 1 to 3 ft are noted elsewhere. Scattered showers and thunderstorms are active north of 18N, mainly over the larger land masses due to afternoon sea breezes, and over the far southwest Caribbean near the monsoon trough. For the forecast, the moderate to fresh trade winds will continue in the central and eastern Caribbean the entire forecast period, except for developing fresh to strong winds in the south-central waters Tue night into Wed. Gentle to locally moderate winds will prevail elsewhere. Seas will be moderate in the eastern half of the basin and slight elsewhere. ...ATLANTIC OCEAN... Please read the Special Features section for details about T.S. Gert, T.S. Katia, Invest AL95 and the large swell over the western Atlantic. Along with the immediate winds and seas related to Gert, the remnant low of Idalia is still causing fresh to strong SW to W winds and rough seas south and southwest of Bermuda, as far south as 28N. An associated cold front reaches from 31N55W to the Turks and Caicos Islands. Scattered showers and a few thunderstorms are active near the front north of the Mona Passage. Gentle to moderate breezes and 4 to 6 ft seas are noted elsewhere across the basin. For the forecast west of 55W, the Idalia remnant low continues to move farther north from the area. The strong winds around the low will diminish across the NE offshore waters by late tonight into early Monday. Rough seas will gradually subside tonight into Tue. Tranquil conditions will settle across the area and continue through early Fri. $$ Christensen