000 AXNT20 KNHC 161040 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 639 AM EDT Sun Jul 16 2017 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 1100 UTC. ...TROPICAL WAVES... A central Atlantic tropical wave has an axis extending from 04N48W to 15N45W, moving westward at 5 to 10 knots. The wave has large areas of dry Saharan air to its NE and NW, but remains embedded in an area of deep layer moisture. Scattered moderate and isolated strong convection is present from 05N to 10N between 46W and 55W. A central Caribbean tropical wave has an axis extending from northern Colombia at 09N76W to between Haiti and Jamaica at 19N75W, moving westward around 20 kt. Scattered moderate and isolated strong convection associated with this wave is over northern Colombia, extreme western Venezuela and the adjacent coastal waters from 10N to 13N between 71W and 80W. The latest rawinsonde sounding from San Juan suggests some of this convection could produce gusty winds. The wave is expected to exit the central Caribbean this afternoon, cross the western Caribbean Monday and Tuesday. A western Caribbean tropical wave has an axis extending from western Costa Rica at 09N84W to the Western Tip of Cuba near 22N84W, moving westward at around 20 knots. TPW satellite imagery shows this wave is only embedded in a modest layer of moisture. There is no significant convection associated with this wave. This wave is entering Central America and will cross the remainder of the western Caribbean and enter the Yucatan Peninsula by this evening. ...ITCZ/MONSOON TROUGH... The Monsoon Trough axis extends from Senegal in west Africa near 14N17W to 11N22W to 08N49W. The ITCZ continues from 08N49W to just north of the coast of Suriname in South America near 06N54W. Aside from the convection related to the tropical wave near 46W, scattered moderate and isolated strong convection is present from 09N to 12N between 15W and 30W and from 03N to 12N between 30W and 46W. ...DISCUSSION... GULF OF MEXICO... A weak surface trough stretches from 25N94W to 27N92W in the north central Gulf of Mexico to the south of Louisiana. Otherwise, a weak high pressure ridge along the northern Gulf Coast is maintaining a light to gentle SE winds over the Gulf. Upper-level winds converging between high pressure along the northern Gulf Coast and a low pressure trough over the southern Gulf is inhibiting convection, except for the convection associated with diurnal troughing over the Yucatan, which is beginning to move over the Bay of Campeche. This weather pattern is expected to continue over the Gulf during the next 24 hours. CARIBBEAN SEA... A couple of tropical waves are moving through the Caribbean Sea. See the tropical waves section above for details. Other than the tropical wave over the central Caribbean, upper-level winds converging over the basin between high pressure over northern South America and a low pressure trough over Hispaniola and Cuba are inhibiting convection. A relatively light pressure gradient over the area is generating light to moderate trades, except for fresh to locally strong trades along the coast of Colombia and in the vicinity of the Gulf of Venezuela. Fresh to strong trades are expected to return to the central Caribbean by Monday evening as high pressure to the north strengthens. ...HISPANIOLA... Generally fair weather prevails across the island. A passing tropical wave produced some convection over Haiti yesterday evening but shower coverage over western Hispaniola has diminished. Drier weather is anticipated today as the tropical wave over the central Caribbean continues heading farther west. ATLANTIC OCEAN... A tropical wave continues crossing the central Atlantic. See the tropical waves section above for details. A surface trough is analyzed over the western Bahamas from 24N79W to 26N78W. The trough is interacting with a small upper-level low centered near 26N79W to produce isolated thunderstorms between the Bahamas and Cuba within 45 nm either side of a line from 22N75W to 24N79W. This system is expected to continue heading west toward the Straits of Florida today and into the eastern Gulf of Mexico tonight. Other troughs are analyzed from 26N48W to 30N44W and from 27N67W to 30N65W. Both of these troughs are weak and neither one of these has significant convection associated with it. The remainder of the basin remains dominated by a broad surface ridge, anchored by a 1028 mb high centered just SW of the Azores near 37N31W. For additional information please visit http://www.hurricanes.gov/marine $$ McElroy