024 AXNT20 KNHC 111019 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1205 UTC Tue Jul 11 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. ...TROPICAL WAVES... A eastern Atlantic tropical wave has its axis along 24W from 05N to 15N. It is moving westward at 10-15 kt. A small cluster of moderate convection is noted where the wave meets the ITCZ near 10N24W. An active and well defined tropical wave is approaching the Lesser Antilles. Its axis extends from 19N54W to near the Suriname/Guyana border. This wave is moving westward at about 20 kt. Scattered moderate to isolated strong convection is seen mainly ahead of the wave axis from 14N to 18N between 51W and 61W. Resent scatterometer data indicate fresh to strong easterly winds on either side of the wave, mainly N of 15N. Seas of 6 to 9 ft are within these winds. The wave is located SE of an upper-level trough that extends across the Leeward Islands into the eastern Caribbean to near 15N70W. This is likely enhancing the convective activity associated to the wave that is already affecting the Lesser Antilles, mainly S of Guadeloupe. A western Caribbean Sea tropical wave has its axis along 81W, south of 21N. It is moving westward at 10 to 15 kt. This wave extends from central Cuba to western Panama. Scattered moderate convection is present near the northern portion of the wave axis affecting parts of central Cuba and the Cayman Islands. A cluster of moderate to strong convection is over eastern Panama. ...MONSOON TROUGH/ITCZ... The monsoon trough axis reaches the Atlantic through the coast of Mauritania near 19N16W and extends SW to near to 11N23W. The ITCZ begins at 10N25W and continues to 06N40W and northwestward to 10N55W. Aside from convection that is associated to tropical waves, scattered moderate convection is noted on both side of the ITCZ from 04N to 08N between 32W and 40W. A cluster of moderate to isolated strong convection is along the coast of W Africa from 08N to 11.5N E of 16W. GULF OF MEXICO... Isolated showers and thunderstorms are over the northern Gulf E of 92W, and over N florida ahead of an upper-level trough that extends over the SE of United States. Similar convective activity is also observed near the N coast of western Cuba. The latter is the result of an upper-level low spinning over the NW Caribbean. Another area of scattered showers and thunderstorm is noted in the Bay of Campeche is association with a surface trough. The remainder of the Gulf of Mexico is under the influence of the western periphery of the broad subtropical ridge positioned over the central Atlantic. This pattern is suppressing the development of deep convection, especially in the southeastern part of the Gulf, where a batch of dry Saharan dust is noted. Recent scatterometer data clearly show the wind shift associated with the trough that develops over the Yucatan Peninsula during the evening hours. Moderate to fresh winds are associated with this trough. Elsewhere across the Gulf waters, a gentle to moderate anticyclonic flow is seen. Seas are generally 2 to 4 ft across the western Gulf, and 1 to 3 ft across the eastern Gulf. For the forecast, a ridge will continue to dominate the Gulf waters while a trough will develop 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 anticyclonic flow and slight seas will prevail. CARIBBEAN SEA... The pressure gradient between the 1025 mb high pressure located over the central Atlantic near 27N42W and lower pressure in NW South America sustain fresh to strong winds over the central Caribbean, with strong to near gale force winds near the coast of Colombia, and in the Gulf of Venezuela. This was confirmed by recent satellite derived wind data. These winds also support seas of 8 to 11 ft based on altimeter data, with the highest seas near the coast of Colombia. An area of fresh to locally strong trade winds with seas of 5 to 7 ft, is noted just S of Puerto Rico to about 15N. Elsewhere, mainly moderate to fresh winds and seas in the 3 to 5 ft range prevail, except in the lee of Cuba where light and variable winds are noted with seas of 1 to 3 ft. An upper-level low over the NW caribbean combined with a tropical wave along 81W is helping to induce showers and thunderstorms over parts of Cuba and the Cayman Islands and regional waters. The western extent of an upper-level trough supports a band of showers and thunderstorms across the eastern Caribbean roughly along 15N and E of 73W. For the forecast, fresh to strong winds and rough seas will continue over the central Caribbean through the weekend. Strong to near gale force winds are likely off Colombia and in the Gulf of Venezuela mainly at night. Fresh to strong winds are expected in the Gulf of Honduras tonight, then mainly moderate to fresh winds will prevail the remainder of the forecast period. Moderate to fresh trade winds and moderate seas will prevail over the E Caribbean and the tropical Atlantic waters through Sat night. A tropical wave, currently located along 56W, will bring an increase in winds and seas across the waters just E of the Leeward Islands today, and over the NE Caribbean tonight into on Wed. Fresh to strong NE winds are expected in the Windward Passage ahead of the wave axis by Wed night. ATLANTIC OCEAN... The Atlantic forecast region is dominated by a ridge anchored by a 1025 mb high pressure located near 27N42W. Another high pressure center of 1022 mb is located mid-way between the Azores and the Madeira Islands. Convection is limited across the basin. The pressure gradient between the ridge and a frontal system off the eastern United States is sustaining moderate to fresh southwest winds north of 28N and west of 55W. Moderate to locally fresh E trade winds are noted south of 22N and west of 55W. Seas in the waters described are 4 to 7 ft. Elsewhere W of 55W, light to gentle anticyclonic winds and seas of 3-5 ft prevail. The Saharan Air Layer tracking product from CIMSS reveals that another outbreak of Saharan dust is occurring off the coast of Africa and will be propagating westward over the next several days. African dust reaches Puerto Rico and Hispaniola. Moderate to strong northerly winds are present between the Canary Islands, and near the coast of Mauritania, particularly from 19N to 21N E of 22W where seas are in the 7 to 9 ft range. Moderate to fresh winds are noted elsewhere across the tropical Atlantic with seas of 5 to 8 ft while mainly light to gentle winds are occurring along the ridge axis with seas of 3 to 5 ft. For the forecast W of 55W, a ridge will remain in place across the forecast waters while weakening some by Wed as a developing low pressure moves SE and crosses near the NE waters. Fresh W to NW winds and seas to 8 ft, in association with the low, are expected to impact the NE waters tonight into Wed. The northern end of a tropical wave is forecast to affect the waters north of the Leeward Islands and Puerto Rico on Wed, and north of Hispaniola, including approaches to the Windward Passage by Wed night. In addition, an area of fresh to locally strong E winds are expected off Hispaniola over the next several days. Light to gentle winds will persist along the ridge axis. Looking ahead, an area of disorganized showers and thunderstorms is currently located a few hundred miles to the east-northeast of Bermuda. An area of low pressure is forecast to develop from this area in the next day or so, and environmental conditions are then forecast to be marginally conducive for further development. A subtropical or tropical depression could form during the latter part of this week as the system moves generally eastward. By the weekend, the low should turn northward bringing the system over cooler waters, likely limiting additional development. Refer to the latest NHC Tropical Weather Outlook at www.hurricanes.gov for more details. $$ GR