165 AXNT20 KNHC 092346 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0005 UTC Mon Jul 10 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 2345 UTC. ...TROPICAL WAVES... A central Atlantic tropical wave has its axis along 42W from 06N to 19N, moving westward at about 20 kt. Scattered moderate convection is on either side of the wave from 09N to 16N between 36W-50W. Latest scatterometer data showed fresh northeast-east winds in the vicinity of the tropical wave. A tropical wave has entered the eastern Caribbean Sea. It has its axis along 61W/62W from 09N to 19N, and is moving westward at 15-20 kt. No significant convection is noted at this time. A central Caribbean tropical wave has its axis extending from the southeastern Bahamas to across western Haiti, and continues to inland Colombia near 08N75W. It is moving westward about 15 kt. Only isolated showers are seen from 12N to 16N between 69W-75W. The northern tip of a tropical wave is analyzed in the western Bay of Campeche near 96W and south of 21N. It is moving westward at 10 kt. Isolated showers and thunderstorms are within 60 nm either side of this portion of the wave. Scattered moderate convection is occurring in the W Bay of Campeche, south of 22N. ...MONSOON TROUGH/ITCZ... The monsoon trough axis enters the Atlantic through the coast of Senegal near 14N17W. It extends southwestward to near 11N20W, where it transitions to the ITCZ and continues to 11N30W to 10N38W. The ITCZ resumes at 08N45W and continues to the coast of Guyana near 07N58W. Aside from convection mentioned above under Tropical Waves, scattered moderate convection is within 120 nm south of the ITCZ between 35W-38W, and north of the ITCZ from 09N to 12N between 50W-60W. This activity trails the tropical wave that is in the eastern Caribbean Sea. GULF OF MEXICO... Weak Atlantic high pressure ridging stretches southwestward across South Florida, the Florida Keys and the Straits of Florida to the southeastern Gulf waters. Its associated gradient is allowing for generally light to gentle anticyclonic flow across the basin as depicted in a partial ASCAT data pass and confirmed by the buoys across the Gulf. Seas throughout are 2-4 ft, except for slightly higher seas of 3-5 ft in the central and west- central Gulf zones. Scattered to numerous showers and thunderstorms, some on the strong side producing frequent lightning and locally strong winds and seas, are moving east-southeastward over the far northeastern Gulf. This activity is ahead of an upper-level shortwave trough and spreads well inland northern Florida, the Florida panhandle, Alabama, Mississippi and Louisiana. For the forecast, the weak high pressure ridge will continue to dominate the Gulf waters while a trough develops over the Yucatan Peninsula each evening and move offshore. Under this weather pattern, moderate to fresh winds will pulse north and west of the Yucatan peninsula during the late afternoon and evening hours. Elsewhere, gentle to moderate winds and slight seas will prevail. CARIBBEAN SEA... Please see the Tropical Waves section above for more details on a couple of tropical waves that are moving through the basin. Fresh to strong trade winds are in the south-central Caribbean as a result of the pressure gradient between broad central Atlantic high pressure and relatively lower pressure found in Colombia, where the climatological low is located. Trade winds to near gale-force are expected within 90 nm of Colombia tonight. Seas with the fresh to strong trade winds and with the expected winds to near gale-force are 6-9 ft. Fresh trade winds are elsewhere in the central Caribbean along with seas of 5-7 ft. In the eastern and western Caribbean, trade winds are gentle to moderate along with seas of 3-6 ft. An area of Saharan Dust (also referred to as the Saharan Air Layer) is approaching the Lesser Antilles. Scattered showers and few thunderstorms are in the southwestern Caribbean south of 12N and west of 75W to the coasts of Costa Rica and Panama. For the forecast, the tropical wave moving across the central Caribbean and a new wave entering the E basin today will support fresh to strong winds and rough seas in this region of the basin through Tue evening. Fresh to locally strong winds will pulse in the Gulf of Honduras at night through Tue, then mainly moderate to fresh winds will prevail through Fri night. Generally moderate to fresh winds will persist in the E and SW basin through the forecast period. Looking ahead, a third tropical wave is forecast to bring an increase in winds and seas across the NE Caribbean Tue night into Wed. The wave will move across Puerto Rico through late Wed and across Hispaniola Wed night into Thu. This will induce fresh to strong NE winds along the Windward Passage Wed night. For the forecast, the tropical waves moving across Caribbean will support fresh to strong winds and rough seas in this region of the basin through Tue evening. Fresh to locally strong winds will pulse in the Gulf of Honduras at night through Tue, then mainly moderate to fresh winds will prevail through Thu night. Generally, moderate to fresh winds will persist in the eastern and southwestern sections of the basin for the next few days. Looking ahead, a new tropical wave is forecast to bring an increase in winds and seas across the northeastern Caribbean Tue night into Wed. The wave will move across Puerto Rico through late Wed and across Hispaniola Wed night into Thu. Its associated gradient will induce fresh to strong northeast winds along the Windward Passage during this period. ATLANTIC OCEAN... A 1025 mb high pressure centered is analyzed near 29N38W, and a 1026 mb high is located near 32N33W. In general, broad high pressure covers the Atlantic north of 20N and east of 70W. West of 70W, the high pressure becomes a ridges axis that stretches southwestward to South Florida, the Florida Keys and the Straits of Florida. South of 20N, the gradient is allowing for moderate to fresh trade winds along with seas of 6-8 ft. North of 20N, the gradient supports gentle to moderate anticyclonic winds along with seas of 3-6 ft. Scattered showers and thunderstorms are occurring north of 28N between 63W-75W. This activity is shifting eastward as it is being sustained by an upper-level trough that extends from offshore the eastern U.S seaboard, southwestward to the NW Bahamas. Scattered to numerous showers and thunderstorms are pushing offshore central and northern Florida to near 79W. This activity contains frequent lightning and may be accompanied by locally higher winds and seas. An area of Saharan Dust (also referred to as the Saharan Air Layer), typical for this time of year, is approaching the Lesser Antilles. An upper-level low is identified on water vapor imagery to be near 26N52W. Last GOES-E visible imagery shows high clouds rotating cyclonically from 21N-29N and between 50W-55W. For the forecast W of 55W, surface high pressure and associated ridging will remain in place over the southwestern N Atlantic waters through Fri night, while a trough moves across the Carolinas and Georgia adjacent waters through mid-week. The pressure gradient between these two features will support moderate to fresh southwest winds north of about 27N, increasing briefly to fresh to strong speeds through Mon mainly across the waters N of 29N between 65W-75W. Moderate to locally fresh trade winds are expected south of 22N, occasionally pulsing to 25 kt off Hispaniola through Fri night. Light to gentle winds will persist elsewhere along the ridge axis or to the east of the Bahamas. $$ Aguirre