000 AXNT20 KNHC 221041 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 641 AM EDT MON AUG 22 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 0600 UTC surface analysis and satellite imagery through 1030 UTC. ...SPECIAL FEATURES... Tropical depression Fiona is centered near 24.4N 58.4W at 22/0900 UTC or about 456 nm northeast of the northern Leeward Islands, moving west-northwest at 16 kt. Estimated minimum central pressure is 1008 mb. Maximum sustained wind speed is 30 kt with gusts to 40 kt. Scattered heavy showers and isolated tstms are from 22N to 26N between 54W and 58W. Please see latest NHC Forecast/Advisory under the AWIPS/WMO headers MIATCMAT1/WTNT21 KNHC for more details. A tropical wave is in the east Atlantic extending from 06N-16N with axis near 24W, moving west at 15 kt within the last 24 hours. The wave is associated with a 1008 mb low that is centered near 11N24W. Abundant moisture in the wave environment, favorable deep layer wind shear and middle to upper level diffluence favor numerous heavy showers and isolated tstms from 09N to 15N between 25W and 28W. Scattered heavy showers are from 05N to 09N between 22W and 37W. Environmental conditions are conducive for development, and a tropical depression is likely to form later today while the system moves westward to west-northwestward over the eastern tropical Atlantic Ocean. ...TROPICAL WAVES... Tropical wave is in the central Atlantic extending from 08N-19N with axis near 47W, moving W at 15-20 kt within the last 24 hours. There is a 1010 mb low near 14N47W associated with the wave. Saharan dry air and dust in the wave environment limit the convection to scattered showers and tstms from 14N to 18N between 44W and 52W. Dry air near this system is expected to inhibit significant development during the next few days while the disturbance moves westward to west-northwestward. Environmental conditions could become more conducive for development late this week when the system is expected to move near Hispaniola and the southeastern and central Bahamas. Tropical wave is in the western Caribbean extending from 10N to 21N with axis near 80W, moving west at 15 kt within the last 24 hours. CIRA LPW imagery from the surface to 850 mb show large patches of dry air in the wave environment mainly east of the wave axis. Water vapor imagery continue to show strong dry air subsidence across this region of the Caribbean. This results in a tropical wave devoid of convection at this time. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends across Africa into the east Tropical Atlantic near 15N16W to 11N24W to 09N36W. The ITCZ begins near 08N48W and continues to 07N58W. Aside from the convection related to the tropical waves, scattered showers are from 06N to 10N between 41W and 47W. ...DISCUSSION... GULF OF MEXICO... Heavy showers and tstms have developed in the Bay of Campeche ahead of a surface trough with axis extending from 20N93W to 15N94W. This trough also support NE fresh to strong wind within 120 nm off the western Yucatan Peninsula coast. Weak surface ridging prevails elsewhere across the basin, being anchored by a 1017 mb high near 27N85W. The ridge continue to provide gentle variable flow across the east Gulf and E-SE gentle to moderate flow elsewhere. Dry air subsidence support fair weather elsewhere. Winds over the eastern Bay of Campeche are forecast to diminish later this morning, but will return again tonight as another heat surface trough move off the Peninsula. Mostly gentle to moderate E-SE winds are expected to prevail elsewhere through Tuesday near sunrise. CARIBBEAN SEA... A tropical wave is moving across the western Caribbean, however no showers are linked to it. For more details about it see the tropical waves section. In terms of winds, the passage of this wave across the central basin tightened the pressure gradient to support fresh to strong trade winds S of 17N between 68W and 82W. Divergent flow over Central America support scattered heavy showers and tstms across eastern Honduras and Nicaragua as well as within 60 nm off the Nicaragua coast. Water vapor imagery continue to show very dry and stable air across the remainder Caribbean, thus supporting fair weather. The area of fresh to strong trades is forecast to prevail through Tuesday sunrise. ...HISPANIOLA... Fair weather prevails across the island this morning. Moisture is forecast to increase across the island this afternoon supporting showers and possible thunderstorms. Fair weather is forecast Tuesday, but weather conditions deteriorate again early Wednesday morning as another moist airmass moves over the Island. ATLANTIC OCEAN... Tropical depression Fiona and a tropical wave over the eastern Atlantic are the main features across the basin. Please see the Special Features section above for more details. The other feature of interest in the basin is a tropical wave in the central Atlantic with possibilities of becoming a tropical cyclone late this week. For more details refer to the Tropical Waves section. A 1015 mb center of high pressure is located near 27N72W, which is forecast to strengthen and move over NE Florida adjacent waters early Tuesday morning. The remainder of the area is dominated by a surface ridge anchored by a 1028 mb high centered near 42N37W. For additional information please visit http://www.hurricanes.gov/marine $$ RAMOS