000 AXNT20 KNHC 211205 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 AM EDT Thu Jun 21 2018 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 32N. The following information is based on satellite imagery, weather observations, radar and meteorological analysis. Based on 0600 UTC surface analysis and satellite imagery through 1115 UTC. ...TROPICAL WAVES... There are four tropical waves between the west coast of Africa and the Lesser Antilles. A tropical wave is along 24W from 03N-12N. The Hovmoller Diagram shows the westward propagation of the wave, that coincides with a modest surge of moistened air based on the TPW product. Convection is limited near the wave's axis. A tropical wave is along 33W/34W from 3N-11N, moving W at 20 knots. This wave shows up well as a low amplitude moisture surge on the TPW animation. Scattered moderate convection is noted where the wave meets the ITCZ. A tropical wave is along 42W from 3N-11N, moving W at about 15 knots. The wave is well depicted in the moisture product. Scattered moderate convection is noted on either side of the wave's axis from 6N-8N between 38W-45W. Another tropical wave is approaching the Lesser Antilles. Its axis is along 58W from 6N-17N, moving W at about 10 knots. The TPW animation shows a surge of moistened air near the wave's axis. A cluster of moderate convection is already affecting Trinidad and Tobago. Scattered moderate convection is seen near 13N58W, and near the southern end of the wave's axis, from 6N-8N between 55W- 58W. Moisture associated with this feature will continue to affect the Windward Islands this morning. The wave will then move across the eastern Caribbean this afternoon through Fri night. The associated moisture is forecast by the GFS computer model to spread out reaching the Leeward Islands later today and tonight, and Puerto Rico on Fri. A tropical wave is moving across the Caribbean. Its axis is along 70W, and extends from Hispaniola to western Venezuela. The wave, combined with an upper-level trough crossing eastern Cuba, is producing scattered showers and tstms across the Windward Passage and parts of Haiti. Lingering moisture from this tropical wave will continue to support showers and isolated thunderstorms across Hispaniola today. Moisture and instability related to this wave will also affect the Windward Passage and eastern Cuba later today. ...MONSOON TROUGH/ITCZ... The monsoon trough passes through the coastal sections of Guinea near 10N13W to 06N21W. The ITCZ continues from 06N21W to 06N30W 05N40W to 05N51W. Outside of the convection associated with the tropical waves, isolated moderate convection is from 3N-7N between 24W-35W. Scattered moderate convection is from 4N-7N between 50W-55W. ...DISCUSSION... GULF OF MEXICO... An area of low pressure over southern Texas will continue to support strong gusty winds, widespread showers and scattered thunderstorms in Texas coastal waters, and over parts of NE Mexico, including coastal waters this morning. Winds and seas in the NW Gulf will diminish further today as the low weakens. A broad ridge across the SE Gulf will support light winds and seas less than 3 ft east of 88W through Tue. A surface trough will develop in the Yucatan Peninsula each afternoon, then move westward across the SW Gulf during the overnight hours, accompanied by fresh east to southeast winds. CARIBBEAN SEA... A tropical wave passing south of Hispaniola will move into the western Caribbean today. A tropical wave along 59W will reach the Lesser Antilles later this morning. Fresh to strong winds are expected in the Gulf of Honduras Fri night through Sun night. Trade winds across the south-central Caribbean will strengthen tonight, then expand in coverage across the basin this weekend as high pressure builds in the central Atlantic. Seas will build to 10-11 ft in the central Caribbean Sat night through Mon night. ATLANTIC OCEAN... An upper-level trough extends from a cyclonic circulation centered near 27N65W to eastern Cuba. Scattered showers and tstms are noted on the SE semicircle of the low affecting mainly the waters from 24N-29N between 60W and 70W. A diffluent pattern aloft between the aforementioned upper-level trough and an anticyclonic circulation located E of the Lesser Antilles is helping to induce this convective activity. High pressure over the east-central Atlantic near 34N33W will slowly shift westward through Sat night, then remain nearly stationary near 30N55W through Tue. The pressure gradient in the central Atlantic associated with this high will support fresh trade winds S of 23N west of 50W, and allow seas to build to 6-7 ft in southern waters E of the Bahamas this weekend. For additional information please visit http://www.hurricanes.gov/marine $$ GR