000 AXNT20 KNHC 080605 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 205 AM EDT Sat Jul 8 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 0000 UTC surface analysis and satellite imagery through 0545 UTC. ...TROPICAL WAVES... A tropical wave is over the far eastern Atlantic with axis extending from 16N23W to 05N25W, moving westward 10-15 kt. The wave is in a region of favorable to neutral wind shear. Atmospheric moisture has increased during the past 24 hours along and to the east of the wave, while last visible imagery from Friday vividly displayed an extensive area of African Saharan dry air and dust to its west, and as also confirmed by the latest Meteosat 9 Saharan African Layer depiction. Convection remains limited to across the far southern extent of the wave axis where it intersects the monsoon trough axis and south of the trough axis. It consists of scattered moderate isolated strong type convection within 120 nm west of the axis from 05N-07N. Scattered moderate convection is within 60 nm east of the axis from 05N-08N. A tropical wave, remnants of Tropical Depression Four, is over the central Atlantic with its axis extending from near 22N52W to 18N53W to 13N53W. It is moving west-northwest around 18 kt. The atmospheric environment surrounding the wave is very moist as observed on latest satellite imagery. Also, the CIRA moisture analysis reveals the presence of deep layer moisture over and near the wave. Deep convection increased during the evening on Friday, however, during the past few hours it has diminished as seen in the satellite loop animation. The remaining convection is noted as a large cluster of the scattered moderate type intensity along and west of the wave axis from 17N-21N, within 60 nm west of the axis. Scattered moderate convection is within 30 nm of 17.5N53W. An Ascat pass from 0110Z last night nicely depicted a northeast to southeast wind shift across the wave axis, with fresh to strong east to southeast winds east of the axis from 17N-20N between the wave and 50W. The wave is forecast to pass to the northeast of the Leeward Islands by Sunday evening attendant with possible brief gusty winds and squalls for portions of the northeast Caribbean. The wave is forecast to approach the SE Bahamas on Monday. A tropical wave is over the eastern Caribbean Sea with axis extending from 19N68W to 15N69W to inland Venezuela near 10N69W, moving westward around 20 kt. The wave is entering an upper level environment of neutral to unfavorable wind shear. The latest water vapor imagery shows subsidence and and associated dry air over and around the wave environment. Isolated showers and thunderstorms moving quickly to the west are seen east of the wave, and also to the west of the wave north of 14N west to near 74W. A tropical wave is over the Bay of Campeche and over southeastern Mexico with axis extending from near 23N91W to inland Mexico at 19N93W. It is moving westward near 18 kt. The wave is embedded in a very moist and unstable atmospheric environment. Clusters of scattered moderate to strong convection are present south of 21N and west of the wave to along and inland the coast of Mexico. Scattered moderate convection is east of the wave south of 21N. The wave is forecast to move across the remainder of the SW Gulf through early this evening, then move inland Mexico tonight. ...ITCZ/MONSOON TROUGH... The Monsoon Trough axis extends from 16N17W to 09N23W to 05N34W. The Intertropical Convergence Zone extends from 05N34W to 03N13W to 03N43W to 4N52W. Aside from the convection related to the tropical wave over the far eastern Atlantic. Scattered moderate isolated strong convection is along and within 120 nm south of the axis between 31W-33W, and within 60 nm north of the axis between 37W-39W. Scattered moderate convection is within 60 nm of the axis between 41W-45W. Scattered moderate to strong convection in clusters are along and just offshore the coast of Africa from 07N-11N. This activity extends inland as swell for 90 nm, and is in advance of the next tropical wave forecast to approach the coast in the near future. ...DISCUSSION... GULF OF MEXICO... A tropical wave is over the Bay of Campeche and extends southward to southeastern Mexico. See above for details on its associated convection. A 1020 mb high is centered over the eastern Gulf near 27N85W. It is producing light to gentle anticyclonic winds across the eastern part of the Gulf north of 26N. Water vapor imagery indicates that a small upper level low is near 25N84W. Ample moisture and instability to its east and southeast is bringing scattered showers and isolated thunderstorms to the SE Gulf waters, and over some of the waters to its east and northeast. Scattered showers and isolated thunderstorms are also over the western Gulf north of the deep convection associated with the tropical wave. This activity is noted from 21N-28N and west of 90W. CARIBBEAN SEA... A tropical wave is moving across the eastern Caribbean. See above for details. Scattered moderate convection earlier seen over western Cuba has dissipated. Scattered moderate convection is along the coast of Cuba from 78W-80W, and extends offshore for about 80 nm. Scattered moderate to isolated strong convection is over the SW Caribbean south of 14N and west of 80W. This activity will persist through the weekend. In the upper levels, anticyclonic flow covers the western half of the sea, while a small upper low is situated over the central part of the Caribbean. Southerly upper flow is present east of the upper low. This is transporting upper debris cloudiness from deep convection over Venezuela northward to portions of the eastern half of the Caribbean. The pressure gradient supports 10-15 kt trades across the Caribbean, except for stronger winds in the 20-25 kt range along the coast of Colombia. ...HISPANIOLA... Scattered showers moving west-northwest are over the eastern section of Hispaniola due to the approach of the tropical wave as discussed above. The scattered showers and possible isolated thunderstorms are expected to continue to affect most of eastern Hispaniola, and some areas of the remainder of the island through the weekend. ATLANTIC OCEAN... The remnants of Tropical Depression Four, now a tropical wave, is over the central tropical Atlantic and a tropical wave is over the far eastern tropical Atlantic. See above for details on these features. Otherwise, strong high pressure of 1030 mb is centered north of the discussion area at 35N37W drifting westward. It extends a ridge southwestward to 32N50W and to central Florida. Water vapor imagery shows an elongated upper low centered near 29N55W and lifting northward. A large upper anticyclone is near 29N69W. Scattered showers and thunderstorms are southeast and south of the upper low from 21N-24N between 51W- 58W, and from 24N-29N between 50W-53W. Scattered showers and isolated thunderstorms moving northwestward are over the western part of the area south of 28N and west of about 75W. An extensive area of African Saharan dust is situated over the eastern and central Atlantic E of 53W, and is gradually shifting westward. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre