000 AXNT20 KNHC 231201 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Sun Jul 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 0600 UTC surface analysis and satellite imagery through 1145 UTC. ...SPECIAL FEATURES... Recently downgraded Tropical Storm Don is centered near 42.6N 48.9W at 23/0900 UTC, or about 300 nm SE of Cape Race Newfoundland moving NNE at 14 kt. Estimated minimum central pressure is 993 mb. Maximum sustained wind speed has diminished to 55 kt with gusts to 65 kt. Seas near the center are up to 30 ft. Satellite imagery shows that Don's eyewall convection has become fragmented. Scattered to numerous moderate convection is confined to within 90 nm of the center in the eastern semicircle, and from 44N to 46N between 47W-49W where the convection is embedded within moderate to heavy rain patches. Small clusters of showers and thunderstorms denote an outer rainband are within 30 nm of line from 42N52W to 41N51W and also within 30 nm of 41N48W. Don is forecast to turn northeastward later today and east-northeastward on Mon. Further weakening is forecast, and Don is likely to lose tropical characteristics by early on Mon. Please read the latest HIGH SEAS FORECAST issued by National Hurricane Center at website https://www.nhc.noaa.gov/text/MIAHSFAT2.shtml and the latest T.S. Don Forecast/Advisory and Public Advisory at www.hurricanes.gov for more details. ...TROPICAL WAVES... An eastern Atlantic tropical wave has its axis along 23W from 04N to 19N. It is moving westward at 10-15 kt. Scattered moderate convection is seen from 05N to 12N and between 16W-27W. Dry air to the north of the wave is inhibiting convection from forming there. A central Atlantic tropical wave has its axis along 36W/37W from 05N to 19N, moving westward at 10-15 kt. Scattered moderate convection is ahead of this wave from 03N to 06N between the wave and 46W. Isolated showers and thunderstorms are east of the wave axis to 30W and from 04N to 07N. A western Caribbean tropical wave has its axis along 86W and south of 19N. It is moving westward at 10-15 kt. The interaction between the wave axis and the eastern Pacific monsoon trough is producing scattered showers and a few thunderstorms south of 14N and west of 80W to the coast of Panama. ...MONSOON TROUGH/ITCZ... The monsoon trough axis enters the Atlantic through the coast of Mauritania near 20N16W and continues southwestward to 12N22W and to 11N30W to 11N39W to low pressure (Invest 95L) near 11N45W 1012 mb and to 12N51W. In addition to convection associated to the tropical waves as described above, scattered moderate to isolated strong convection is within 60 nm south of the trough between 46W-50W and from 12N to 15N between 45W-50W. ...GULF OF MEXICO... A stationary front is draped across the southern United States. Earlier it was enhancing the shower and thunderstorm activity across the northern Gulf coast. This activity is forecast to re-develop today. Isolated showers and thunderstorms are over northern Gulf of Mexico waters east of 92W. Farther south, scattered showers and isolated thunderstorms are seen in the eastern Bay of Campeche. The remainder of the Gulf remains under the western periphery of the subtropical ridge positioned near the Azores. Moderate or weaker winds and seas of 1-3 ft are prevalent across the basin. For the forecast, weak high pressure over the area will change little into the early part of the week. This will support mainly gentle to moderate winds, except over the eastern Bay of Campeche where winds will be enhanced by a thermal trough that will emerge off the Yucatan Peninsula daily during the overnight hours. ...CARIBBEAN SEA... Please see the Tropical Wave section above for details on ongoing convection that is the southwestern Caribbean Sea. The remainder of the basin is under the influence of a subtropical ridge positioned near the Azores. Saharan dust covers most of the Caribbean, resulting in drier conditions, above normal temperatures and reduced visibility. The pressure gradient between the aforementioned ridge and lower pressures in northern South America continues to support fresh to strong easterly trade winds in the central Caribbean and the Gulf of Honduras. The strongest winds are occurring off northern Colombia. Over the rest of the Caribbean, moderate or weaker winds prevail. Seas are 7-10 ft over the central Caribbean and the Gulf of Honduras and mostly 4-6 ft elsewhere. For the forecast, the pressure gradient between the Bermuda High and lower pressure in Central America and northern South America will maintain strong trades across the central Caribbean into Sun. Winds should diminish slightly to fresh to strong tonight through Wed. Fresh to locally strong trades will develop over the Gulf of Honduras this evening and diminish Mon afternoon. These winds develop again Mon evening and diminish early Tue. Low pressure over the tropical N Atlantic well east of the forecast waters is expected to weaken to a trough during the early part of the week as it approaches the Lesser Antilles. Some increase in winds and seas may accompany the trough. ...ATLANTIC OCEAN... Please see the Special Features section for information on recently downgraded Tropical Storm Don in the north-central Atlantic. A 1012 mb low pressure system, designated as Invest 95L, is located near 11N45W. Satellite imagery shows increasing scattered to numerous moderate convection from 10N to 15N between 46W-50W. Fresh to locally strong northeast to east winds are north of the low to near 19N and between 40W-48W. Seas with these winds are 6-8 ft. Although environmental conditions are only forecast to be marginally conducive for some gradual development, this system could still become a tropical depression during the next few days while it moves westward across the tropical Atlantic and eastern Caribbean Sea. Unfavorable upper-level winds are forecast when the system moves into the central Caribbean around midweek, decreasing the chances of formation. Interests in the Lesser Antilles should monitor the progress of this system. The disturbance has a low chance of development over the next 48 hours. Refer to the latest Tropical Weather Outlook at www.hurricanes.gov for more details. Scattered moderate convection is occurring from 26N to 30N between 66W-70W. Farther west, an outflow boundary is moving south off central Florida and near the NW Bahamas. It has generated scattered showers and isolated thunderstorms within 30 nm of line from 27N78W to 27N74W. The rest of the western Atlantic (west of 55W) remains under the western periphery of the subtropical ridge positioned near the Azores. Moderate or weaker winds and generally seas of 3-5 ft continue to the west of 55W. Over the remainder of the tropical Atlantic, the pattern is dominated by a 1031 mb high pressure near the Azores. The strong pressure gradient between the aforementioned ridge and lower pressures in NW Africa supports fresh to near gale-force northerly winds in the eastern Atlantic, mainly north of 19N and east of 35W. This was confirmed by an overnight ASCAT data satellite pass. The strongest winds are noted north of 25N and east of 22W. Seas in the affected area are 6-9 ft. Moderate or weaker winds and slight to moderate seas are present over the remainder of the tropical Atlantic. For the forecast west of 55W, weak high pressure over the area will change little during the next few days. Fresh trades may pulse nightly N just N of Hispaniola and over the Windward Passage starting tonight. Elsewhere across forecast waters, winds will be moderate or weaker over most of the western half of the area and mostly at moderate to fresh speeds elsewhere. $$ Aguirre