169 AXNT20 KNHC 151731 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 UTC Sat Jun 15 2024 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 1200 UTC surface analysis and satellite imagery through 1710 UTC. ...SPECIAL FEATURES... Heavy Rainfall over Central America and Mexico: A Central American Gyre (CAG), which is a broad low to mid level cyclonic circulation centered over the Central American continent, continues to develop. Widespread deep convection driven by the CAG is expected this weekend through Friday June 21. Heavy rainfall with this event is expected along the Pacific coast of Chiapas State of Mexico, Guatemala, Honduras, El Salvador and northwestern Nicaragua. This heavy rainfall may cause life- threatening flash floods and mudslides, especially in areas of hilly terrain. Heavy rainfall is also possible across Quintana Roo, Yucatán, Tabasco, and Veracruz this week. Please refer to bulletins and forecasts from your local weather forecast and emergency management offices for specific information. ...TROPICAL WAVES... A tropical wave is along 20W, from 15N southward, moving westward around 10-15 kt. Convection is described in the monsoon trough section. A central Atlantic tropical wave is analyzed along 53W this morning based on Upper Air sounding data from Cayenne, French Guiana. The wave extends from 17N southward. It is moving west at 10-15 kt. Scattered moderate convection is from 06N to 13N between 51W and 59W. A central Caribbean tropical wave has its axis near 77W south of 15N, moving westward at 10-15 kt. Convection is described in the Monsoon Trough section. This wave will soon be absorbed into the broad low to mid level cyclonic circulation associated with the Central American Gyre described in the Special Features sections. ...MONSOON TROUGH/ITCZ... The monsoon trough enters passes off the coast of Africa near 16N16W to 08N20W to 05N33W. The ITCZ continues from 05N33W to 06N50W. Scattered moderate convection is from 04N to 10N east of 28W. The Central American Gyre described in the Special Features is lifting the East Pacific Monsoon Trough north across the western Caribbean. This monsoon trough currently extends from 1008 mb low pressure near 12N84W along the coast of Nicaragua to 11N74W in NW Colombia. Scattered moderate isolated strong convection is from 08N to 15N west of 74W, including within the Gulf of Honduras. GULF OF MEXICO... Please read the SPECIAL FEATURES section for information on HEAVY RANFALL across Quintana Roo, Yucatán, Tabasco, and Veracruz this week. A surface trough extends from near Tampa Bay, FL to the central Gulf near 25N87W. Another surface trough extends from 22N85W to 1008 mb low pressure near 18N92W along the coast of Mexico. Scattered moderate convection is in the SE Gulf, Florida Straits, and W Atlantic from 23N to 26N between 77W and 87W. Satellite scatterometer data just received indicates a surge of fresh to strong S to SE winds from 24N to 26N between 83W and 87W, with seas of 3-5 ft. Elsewhere in the Gulf, E to NE winds are gentle to moderate with 3-5 ft seas. For the forecast, the aforementioned surface troughs will shift NW and dissipate through tonight. A broad low to middle level cyclonic circulation, a Central American Gyre, is centered over the Yucatan Peninsula and Central America this morning, and is expected to become better organized this weekend, as it drifts westward. Environmental conditions appear conducive for a tropical cyclone to develop from this broad area of low pressure, and a tropical depression could form over the southwestern Gulf during the middle part of next week. Active convection across the southeast Gulf this morning, along with increasing winds and building seas, are expected with this system in the early to mid part of next week, mainly impacting the south-central and northwest Gulf. CARIBBEAN SEA... Please read the SPECIAL FEATURES section for information on HEAVY RANFALL across Quintana Roo and Yucatán this week. Please read the MONSOON TROUGH/ITCZ section for information on active strong convection in the W Caribbean. Moderate to fresh E to SW winds prevail over the central and western Caribbean, with 5-7 ft seas across these waters. Gentle to moderate trades are noted in the E Caribbean with 3-5 ft seas. For the forecast, the Central American Gyre will bring fresh to strong SE winds and scattered showers and thunderstorms across portions of the western and northwestern Caribbean over the next few days. Expect increasing winds and building seas over the western Caribbean, including the Gulf of Honduras, through Tue in association with the gyre. ATLANTIC OCEAN... 1015 mb low pressure centered near 28N77W just north of the Bahamas, with a trough extending to Cape Canaveral, FL, and another trough extending northeast of the low out of the area. Scattered moderate convection is in the SE Gulf, Florida Straits, and W Atlantic from 23N to 26N between 77W and 87W. A couple of weak troughs are across the western and central Atlantic waters. Weather across the Atlantic is guided by 1030 mb high pressure centered north of the area. Satellite scatterometer from this morning indicates moderate or weaker trades across most of the basin, with 4-6 ft seas. In the far eastern Atlantic, NE winds are fresh between the Canary Islands and Cabo Verde, with 6-8 ft seas in this region. For the forecast west of 55W, the trough north of the Bahamas will shift eastward and exit the region through early next week, with active convection continuing ahead of it. Looking ahead, expect fresh E winds west of 70W by late Tue, as high pressure builds north of the area, behind the exiting trough. $$ Mahoney