000 AXNT20 KNHC 200403 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 0605 UTC Thu May 19 2022 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 0000 UTC surface analysis and satellite imagery through 0400 UTC. ...SPECIAL FEATURES... Global models continue to suggest a Central American Gyre (CAG) will form across Central America and the adjacent southwest Caribbean by Fri, and then gradually shift west to northwest across Central America through early next week. CAGs tends to enhance the strength of SW monsoon flow, and lift the monsoon trough well north of its typical position. This will increase convergent surface winds and advect abundant tropical moisture northward, triggering widespread strong convection over Central America. Heavy rainfall has begun this evening in portions of Nicaragua, Guatemala, Honduras and El Salvador. Extreme rainfall is possible across the Pacific coasts of Central America, and also over southern Honduras and northeast Nicaragua. There is potential for flash flooding and mudslides, especially across mountainous terrain. Please refer to products issued by your local weather service for more information. ...TROPICAL WAVES... A tropical wave is in the Atlantic with axis along 42W, from 02N to 10N moving west at 20 kt. Associated convection has decreased due to SW upper level wind shear. Isolated moderate convection is noted from 00N to 08N between 45W and 52W. A tropical wave is in the western Caribbean with axis S of 18N along 86W, moving west at 10 kt. Scattered moderate to strong convection is occurring mostly behind the wave, S of 15N between 77W and 85W. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the African coast near 10N14W to 06N18W. The ITCZ continues from 06N18W to 03S42W. Scattered moderate to strong convection is noted in the eastern Atlantic from 04N to 07N between 11W and 16W. ...GULF OF MEXICO... The gradient between surface ridging from the Atlantic and lower pressure over Mexico is supporting moderate to fresh SE flow across the majority of the basin. An abundance of tropical moisture is causing scattered moderate convection in the Florida Straits, extending west to 84W. Seas are 1-3 ft in the eastern Gulf, 4-6 ft in the NW Gulf and 3-5 ft elsewhere. For the forecast, high pressure over the northeast Gulf will shift eastward through Fri, as broad low pressure over Central America gradually shifts west to northwestward. This pattern will allow an area of moderate to fresh southeast winds over the western Gulf to expand eastward across the Gulf Fri night into Sat. Winds and seas will then diminish slightly across most of the basin Sun into Mon as the pressure gradient relaxes, leaving only pulses of fresh to occasionally strong winds at night off the northern and western Yucatan Peninsula. Fresh SE winds may return to the western Gulf by Tue as a trough deepens over the southwest Gulf. ...CARIBBEAN SEA... Please see the Special Features section for information on a potential heavy rainfall event. Surface ridging over the western Atlantic along 27N is supporting moderate to fresh trade winds across the east and central Caribbean, with fresh to strong winds in the south-central Caribbean. Seas are 5-7 ft in these regions, except 7-9 in the south-central Caribbean. Winds are gentle in the SW Caribbean with 2-4 ft seas. Winds are moderate to fresh in the NW Caribbean with 4-6 ft seas. For the forecast, surface ridging over the western Atlantic is supporting moderate to fresh trade winds across the east and central Caribbean, with fresh to strong winds. Winds and seas across the basin will increase tonight into the weekend as the ridge strengthens and broad low pressure over Central America gradually shifts west to northwestward. The strongest winds and highest seas are expected to be over parts of the northwestern and south-central Caribbean during this period. Looking ahead, winds and seas will start to diminish across the basin early next week as the ridge to the north and the lower pressure over Central America weakens. ...ATLANTIC OCEAN... An abundance of tropical moisture is causing scattered moderate convection across the central Bahamas and Florida Straits. A surface ridge along 25N covers the western basin , supporting mainly light to gentle anticyclonic winds, except for moderate S winds along NE FL and moderate SE winds north of Hispaniola. Trade winds increase to moderate south of 17N. High pressure dominates the central Atlantic, with light to gentle winds north of 21N and gentle to moderate winds south of 21N. In the eastern Atlantic, moderate to fresh N-NE winds are observed within 500 nm of the African continent. Seas are slight west of 65W and moderate elsewhere. For the forecast west of 55W, a surface ridge along 28N will lift north to 30N through Fri and strengthen. This pattern will support mainly gentle to moderate breezes across the region through early next week, except for moderate to fresh winds north of Hispaniola starting late Fri. $$ Flynn