000 AXNT20 KNHC 181028 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 628 AM EDT THU AUG 18 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 1015 UTC. ...SPECIAL FEATURES... Tropical Storm Fiona is centered near 16.2N 40.3W at 18/0900 UTC or about 938 nm W of the Cabo Verde Islands moving NW at 14 kt. Estimated minimum central pressure is 1005 mb. Maximum sustained wind speed is 40 kt with gusts to 50 kt. Scattered moderate convection is from 15N-19N between 38W-43W. Please see the latest NHC Intermediate Public Advisory under AWIPS/WMO headers MIATCPAT1/WTNT31 KNHC and the full Forecast/Advisory under the AWIPS/WMO headers MIATCPAT1/WTNT21 KNHC for more details. ...TROPICAL WAVES... A tropical wave is moving across the eastern Atlantic with axis extending from 20N26W to 12N24W, moving west at 15-20 kt. The wave coincides with 700 mb troughing that has emerged off the coast of west Africa. Isolated showers are observed along the wave axis south of 12N mostly enhanced by the presence of the Monsoon Trough. A tropical wave extends across the central Atlantic with axis from 17N51W to 08N53W, moving west at 20 kt. Global model data indicates mid-level energy is focused along the wave axis with plenty of dry Saharan air and dust surrounding the wave. With this, no significant convection is observed across the wave. However, across the southern portion of the wave where it meets the Monsoon Trough, scattered moderate convection prevails south of 11N. A tropical wave is moving across the eastern Caribbean with axis from 19N66W to 10N67W, moving west at 15-20 kt. The wave coincides with a westward surge of mid-level moisture as depicted by SSMI Total Precipitable Water imagery between 63W-68W. Despite this, no significant convection is observed at this time as Saharan dust and dry air prevails across the eastern Caribbean east of 65W inhibiting any activity. A tropical wave is moving southern Mexico and the EPAC with axis from 21N93W to 10N93W, moving west at 10-15 kt. Most of the energy associated with the wave is noted over the East Pacific region, however, scattered moderate convection is occurring across the southern portion of the Yucatan peninsula, Guatemala, and southern Mexico mainly south of 16N between 88W-97W. ...ITCZ/MONSOON TROUGH... The Monsoon Trough extends from the African coast near 14N17W to 15N32W. The Intertropical Convergence Zone extends from 11N42W to 09N60W. Aside from convection associated with the tropical waves, scattered moderate convection is from 10N-14N between 26W-30W and from 08N-11N between 48W-55W. ...DISCUSSION... GULF OF MEXICO... An upper-level anticyclonic circulation is centered over central Mexico near 23N103W and is providing much of the western Gulf with a diffluent environment aloft. To the east; an elongated upper-level low centered over the southeast Gulf and west Atlantic enhancing convection across the Florida peninsula and Gulf waters mainly east of 86W. To the southwest; the northern portion of a tropical wave is moving across the Bay of Campeche enhancing isolated convection mainly south of 20N between 92W-96W. The remainder the the basin is under the influence of a surface ridge anchored by a 1021 high centered over northern Florida near 30N83W. Gentle to moderate SE surface winds prevail across the basin as noted in scatterometer data. A similar weather patter will prevail through the next 24 hours. CARIBBEAN SEA... A tropical wave is moving across the eastern Caribbean. Please refer to the section above for details. The only area with convection at this time remains across the south-central Caribbean, where the proximity of the Monsoon Trough is enhancing scattered moderate convection south of 10N between 76W-82W. Scatterometer data depicts moderate to fresh trades across the basin except fresh to strong winds south of 13N between 73W-77W. Expect through the next 24 hours for the tropical wave to continue moving west with isolated convection. Little change is expected elsewhere. ...HISPANIOLA... Fair weather prevails across the island at this time. These conditions will prevail through the morning/early afternoon hours. A tropical wave currently along 67W will approach the island after that time and increase cloudiness and the possibility of precipitation over the area. ATLANTIC OCEAN... Tropical Storm Fiona is moving across the eastern tropical Atlantic. Please refer to the Special Features section above for details. Two tropical waves are moving across the basin. For more information, refer to the section above. An elongated upper-level low extends from the southeast Gulf of Mexico to the west Atlantic supporting isolated showers mainly west of 74W. To the east; a pair of surface troughs extend from 29N67W to 27N68W and from 28N64W to 24N65W. Scattered moderate convection prevails along the second trough from 23N-29W between 61W-65W. The remainder of the basin is under the influence of a surface ridge anchored by a pair of 1022 mb and 1020 mb highs located near 32N64W and 32N22W. For additional information please visit http://www.hurricanes.gov/marine $$ ERA