000 AXNT20 KNHC 191805 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1805 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 1200 UTC surface analysis and satellite imagery through 1750 UTC. ...SPECIAL FEATURES... Global models continue to suggest a Central American Gyre (CAG) will form across the southwest Caribbean and Central America 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 moisture northward, triggering widespread strong convection over Central America. Expect heavy rainfall commencing across Panama and Costa Rica today, then spreading to parts of Guatemala and Honduras. Extreme rainfall is possible across the Pacific coasts of these countries, and also over southern Honduras and northeast Nicaragua. This will increase the potential for flash flooding and mud landslides, especially near valleys in mountainous terrain. Please refer to products issued by your local weather service for more information. ...TROPICAL WAVES... A tropical wave is in the central Atlantic with axis from 00N to 10N along 39W, moving west at 10-15 kt. Scattered moderate convection is from 0N to 17N between 28W and 48W. A tropical wave is in the western Caribbean with axis S of 18N along 83W, moving west at 5-10 kt. Numerous moderate isolated strong convection is behind the wave S of 14N between 75W and 81W. ...MONSOON TROUGH/ITCZ... The monsoon trough extends from the African coast near 12N16W to 08N21W. The ITCZ continues from 08N21W to 04N28W to 04N35W, then continues from 02N40W to 01N50W. For information about convection, see the tropical waves section. ...GULF OF MEXICO... Surface ridging extends from the W Atlantic across Florida into the eastern Gulf while low pressure dominates the western Gulf. This pattern is supporting moderate to fresh return flow and seas of 3-5 ft W of 90W and light to gentle variable winds with seas to 3 ft E of 90W. For the forecast, high pressure over the northeast Gulf will shift eastward through Fri, as low pressure develops south of the area over Central America. This pattern will allow an area of moderate to fresh southeast winds over the western Gulf to expand eastward across the Gulf by late Fri. Winds and seas will then diminish slightly across most of the basin Sun through early next week as the pressure gradient relaxes, leaving only pulses of fresh to occasionally strong winds at night off the northern and western Yucatan Peninsula. ...CARIBBEAN SEA... Please see the Special Features section for information on a potential heavy rainfall event. Surface ridging over the western Atlantic is supporting moderate to fresh trade winds across the east and central Caribbean, except for fresh to strong winds in the south-central Caribbean, including Colombia adjacent waters and the Gulf of Venezuela. Seas in these regions are in the 5-7 ft range. Gentle to moderate SE winds are elsewhere with seas to 3 ft. Microwave satellite imagery show abundant moist air across the western Caribbean, which coincides with a region of middle to upper level divergent flow. These atmospheric conditions along with the influence of the E Pacific monsoon trough and a tropical wave along 83W is supporting heavy showers and tstms over portions of the SW Caribbean. For further information, see the tropical waves section. For the forecast, winds and seas across the basin will increase tonight into the weekend as the ridge strengthens and broad lower pressure forms over Central America. 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 over the eastern and central Caribbean early next week as the ridge to the north and the lower pressure over Central America weakens. ...ATLANTIC OCEAN... A weak surface ridge covers the SW N Atlantic waters, which is supporting mainly light to gentle variable winds in that region, exept for locally moderate to fresh winds in the Great Bahama Bank and N of Hispaniola and Puerto Rico. Seas in this region are in the 1-3 ft range. The remainder subtropical Atlantic waters are under the influence of a ridge anchored by a 1022 mb high near 28N41W. Recent scatterometer data show light to gentle variable winds in that region as well with seas to 5 ft. For the forecast west of 55W, the surface ridge 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. $$ Ramos