000 AXNT20 KNHC 152359 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 805 PM EDT MON AUG 15 2016 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 1800 UTC surface analysis and satellite imagery through 2315 UTC. ...SPECIAL FEATURES... A tropical wave is over the Eastern Atlantic just west of the Cabo Verde Islands and extends from 16N25W to 06N26W. A 1008 mb low pressure has developed along the wave axis near 9N26W. Clusters of moderate isolated strong convection are noted within about 210 nm NW quadrant of low center. The wave is in a moist environment with pretty good 700 mb signature. Environmental conditions are expected to be conducive for development during the next few days, and a tropical depression is likely to form while the system moves west-northwestward to northwestward toward the central tropical Atlantic. Latest Tropical Weather Outlook gives this system a medium change of tropical development through 48 hours, and a high change of tropical formation through 5 days. ...TROPICAL WAVES... Another tropical wave is over the central tropical Atlantic and extends from 20N46W to 09N47N moving W at 20 kt. The wave is in a moist environment as depicted by the SSMI Total Precipitable Water Imagery, however, dry air with Saharan dust is wrapping around the west side of the wave. The wave has a classic V- structure on satellite imagery, with a swirl of low clouds along the wave axis near 18N. The wave is well defined at 700 mb. Isolated to scattered showers are observed mainly ahead of the wave. A tropical wave is over the Eastern Caribbean and extends from western Puerto Rico to the coast of Venezuela near 11N67W, moving W at 15-20 kt. The San Juan Doppler radar indicates scattered showers and isolated tstms in association with this wave. Some shower activity is also seen across the Caribbean waters, on either side of the wave axis. A low amplitude northward bulge of moisture that extends to about 16N is noted on the TPW product. Moisture associated with the wave is forecast to remain south of 20N as the wave continues west through the central Caribbean tonight and Tuesday. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 15N17W to a 1008 mb low pressure located near 09N26W to 08N38W. The ITCZ continues from 08N38W to 08N47W to the coast of South America near 07N58W. Besides the convection associated with the tropical waves, scattered moderate convection is from 7N-10N between 34W- 36W, and from 06N-08N between 47W-60W. ...DISCUSSION... GULF OF MEXICO... A stationary front extends over Central Texas . A band of showers and tstms is related to the front. Flash flood threat persists along the Texas coast. The mosaic Doppler radar from the SE U.S. shows scattered showers and tstms across the NW Gulf in a southerly wind flow. Similar convective activity is noted over Florida but in an easterly wind flow. A surface ridge dominates the Gulf region. The most recent scatterometer data provide observations of fresh to strong southerly winds across the western periphery of the ridge, but particularly N of 20N between 91W-94W. Similar wind speeds are also noted across the Straits of Florida from the east. A surface trough is analyzed over the Yucatan Peninsula where scattered moderate to isolated strong convection is occurring. A thermal trough is forecast to develop over the Yucatan Peninsula during the afternoons,then move NW across the SW Gulf during the overnight hours and dissipate during the early morning hours. In the upper levels, an upper level high is centered over E Texas helping to induce convection. An upper level low is centered over the central Gulf near 26N88W with a trough extending SW to the Bay of Campeche. Upper diffluence ahead of the trough supports the convection over the Yucatan peninsula. Abundant mid-upper level moisture is over the Gulf. CARIBBEAN SEA... A tropical wave is over the Eastern Caribbean. Please, see the tropical waves section above. Elsewhere, scattered moderate convection is over the NW Caribbean, south of Isle of Youth Cuba, from 18N-21N between 81W-84W. Similar convection is over the SW Caribbean near the coast of Nicaragua. Scatterometer data and buoys observations indicate fresh to strong tradewinds over the central Caribbean with the strongest winds along the coast of N Colombia. These winds are forecast to persist through mid-week, increasing to near gale force along the NW coast of Colombia during the overnight and early morning hours through Wednesday night. Aloft, a ridge dominates the western part of the basin while an inverted trough extends from Haiti to Colombia. Another ridge from the Atlantic covers the eastern Caribbean. ...HISPANIOLA... Scattered showers and isolated tstms were noted over Hispaniola late this afternoon likely associated with the local effects. Similar weather conditions are expected on Tuesday. A tropical wave is forecast to move across the island tonight and tomorrow and could enhance the convective activity during the afternoon and early evening hours. Computer model indicates that the convection associated with the tropical wave should remain south of the island over the next 24 hours. ATLANTIC OCEAN... Two tropical waves are moving westward between the coast of Africa and the Lesser Antilles. Please, see the tropical waves section above. High pressure dominates the entire area with an E to W ridge axis along 30N-31N. The pressure gradient between the ridge and lower pressure over western Africa is producing near gale force winds from the NE across the Canary Islands. A recent scatterometer data confirmed the presence of these winds. The strongest winds are occurring between islands. The ridge will meander just N of the forecast area through Thursday. For additional information please visit http://www.hurricanes.gov/marine $$ GR