095 AXNT20 KNHC 041020 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 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 0600 UTC surface analysis and satellite imagery through 1000 UTC. ...SPECIAL FEATURES... Tropical Storm Gert is centered near 37.6N 51.0W at 04/0900 UTC or 750 nm ENE of Bermuda, moving N at 21 kt. Estimated minimum central pressure is 1000 mb. Maximum sustained wind speed is 45 kt with gusts to 55 kt. A small area of disorganized deep convection has been persisting to the southeast of the center. Gert will likely be absorbed by Post-Tropical Cyclone Idalia later today. A faster north-northwestward to northwestward motion is expected today while Gert moves around Idalia with little change in strength. 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 Depression Katia is centered near 27.7N 33.7W at 04/0900 UTC or 890 nm NW of the Cabo Verde Islands, moving NW at 6 kt. Estimated minimum central pressure is 1008 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. The system is producing a few puffs of deep convection over the northern portion of its circulation. Weakening is forecast, and Katia is expected to become a remnant low later today or tonight, and dissipate in a few days. A generally northwestward motion is expected today, followed by a slow southeastward to south-southeastward motion on Tuesday and Wednesday. Seas to 12 ft are still noted within about 90 nm N semicircle of center. 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. Tropical Atlantic (AL95): Showers and thunderstorms continue to show signs of organization in association with a tropical wave located several hundred miles southwest of the Cabo Verde Islands. Environmental conditions are forecast to be conducive for further development, and this system is expected to become a tropical depression in two or three days. Additional strengthening is likely late this week while the system moves westward to west-northwestward at 15 to 20 mph over the central and western portions of the tropical Atlantic. This system has a medium chance of tropical cyclone formation through 48 hours, and a high chance through 7 days. Please refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. Atlantic Swell Event: rough seas generated by the remnant low of Idalia and Tropical Storm Gert continue to propagate across the Atlantic forecast waters mainly N of 25N between 45W and 74W. Currently, seas are in the 8 to 12 ft range in northerly swell, with the highest seas affecting the waters N of 29N between 55W and 65W. This swell event will continue to subside through mid- week. ...TROPICAL WAVES... Looking ahead, a tropical wave is forecast to move off the African coast in a couple of days. Environmental conditions could support some slow development starting midweek while the wave moves to the west-northwest at 10 to 15 kt over the far eastern tropical Atlantic. This system has a low chance of tropical cyclone formation through 7 days. Please refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. A tropical wave is along 31W moving west at 10 to 15 kt. A 1010 mb low pressure (AL95) is analyzed along the wave axis near 11N. See the Special Features section for more details. A tropical wave is moving across the central Caribbean at 5 to 10 kt. Its axis is along 71W and extends from Hispaniola to western Venezuela. The wave appears to enhance convection over Hispaniola and regional waters as well as over western Venezuela and northern Colombia. Another tropical wave is over Central America with axis along 84W moving W at 10 to 15 kt. Scattered showers and isolated thunderstorms are noted along the wave axis, particularly over the eastern plains of Nicaragua. ...MONSOON TROUGH/ITCZ... The monsoon trough enters the Atlantic through the coast of Mauritania and continues SW to a 1010 mb low located near 11N31W to 11.5N50W. The ITCZ extends from 11.5N50W to 10N60W. Aside from the convection already mentioned in the Tropical Waves section, scattered moderate convection can be found from 05N to 09N between 12W and 20W, within about 90 nm N of the monsoon trough/ITCZ between 43W and 52W, and from 09N to 11N between 52W and 59W. ...GULF OF MEXICO... High pressure of 1018 mb located over the SE CONUS dominates the Gulf region. A weakening stationary front extends from western Cuba to SE Louisiana. A few showers are along the frontal boundary. Recent scatterometer data indicate gentle to moderate E to SE winds across most of the Gulf waters, with the exception of moderate to fresh winds across the offshore waters of W Florida and in the Straits of Florida. Seas are 4 to 6 ft in the Straits of Florida, 3 to 4 ft over the eastern Gulf and the E and central Bay of Campeche, and 1 to 3 ft elsewhere. For the forecast, high pressure over the SE CONUS will support gentle to moderate E to SE winds across most of the basin through mid-week. Afterward, a weak pressure gradient will result in light to gentle winds and slight seas the remainder of the forecast period, with the exception of gentle to moderate winds just W of the Yucatan Peninsula. ...CARIBBEAN SEA... Two tropical waves are moving westward across the basin. Please refer to the Tropical Waves section for more details. Satellite derived wind data provide observations of moderate to fresh trade winds in the wake of the tropical wave located along 71W. Gentle to moderate winds prevail elsewhere. Seas are generally 3 to 5 ft E of 72W, 3 to 4 ft in the NW Caribbean, and 1 to 3 ft elsewhere. Seas of 5 to 6 ft, in northerly swell, are seen in the Caribbean passages E of La Mona Passage. For the forecast, moderate to fresh trade winds and moderate seas 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 and slight seas will prevail elsewhere. ...ATLANTIC OCEAN... Please read the Special Features section for details about T.S. Gert, T.D. Katia, Invest AL95 and the Atlantic swell event. A weakening cold front, attached to the remnant low of Idalia, extends from 31N52W to eastern Cuba. A few showers and isolated thunderstorms are along the frontal boundary. Fresh winds are on either side of the front mainly N of 29N. A weak ridge is noted between the Canary Islands and T.D. Katia. An upper-level low spinning near 28N42W is generating an area of showers with isolated thunderstorms ahead of the above mentioned front, mainly N of 23N between 44W and 52W. For the forecast west of 55W, the front will move eastward over the next couple of days while dissipating. The swell event will gradual subside through mid-week. $$ GR