160 AXNT20 KNHC 210521 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 121 AM EDT Sat Jul 21 2018 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 0515 UTC. ...TROPICAL WAVES... A tropical wave is in the E Atlc with axis extending from 05N-18N along 28W, moving W at 10-15 kt. Saharan dry air and dust continue to prevail in the wave's environment as shown by CIRA LPW and GOES-16 RGBs imagery. This is inhibiting convection at this time. A tropical wave is in the central Atlantic with axis extending from 05N-21N along 45W, moving W at 10-15 kt. The wave is moving across an extensive area of Saharan dry air, which is hindering convection at the time. A low amplitude tropical wave is moving across Venezuela with axis extending from 00N-10N along 66W, moving W at 10-15 kt. Scattered moderate convection is observed with this wave between 62W-70W. This wave is forecast to move to EPAC waters on Mon. A tropical wave is in the west-central Caribbean with axis along 81W, moving W at 15-20 kt. Scattered showers are noted along the wave's axis in the vicinity of the monsoon trough mainly south of 13N. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from the coast of W Africa near 14N17W and continues to 09N40W. The ITCZ begins near 07N47W and continues to South America near 08N59W. No significant convection is observed along these boundaries at this time. ...DISCUSSION... GULF OF MEXICO... A surface trough continues over the northeast Gulf waters from northern Florida near 30N83W to 28N86W. This feature is being supported by a mid-level trough that extends over the eastern CONUS, which also supports a frontal system north of the area. Scattered showers are noted along the trough at this time. Latest scatterometer data show gentle to moderate winds in the vicinity of the trough. Elsewhere, the remainder Gulf is under the influence of a surface ridge, anchored by a 1016 mb high centered near 27N92W. This is providing light to moderate anticyclonic winds across the basin. The trough is forecast to lift NE of the area this morning and surface ridging will prevail thereafter through the weekend. A surface trough will move off the Yucatan Peninsula into the Bay of Campeche each evening, accompanied by fresh nocturnal winds and scattered showers. CARIBBEAN SEA... The majority of the basin is pretty quiet as very dry air prevails across the area. A tropical wave is moving across the west- central portion of the basin, however lacks convection due to the aforementioned conditions. The only region of convection is within 150 nm off the coast of Costa Rica and northern Panama where the EPAC monsoon flow supports scattered showers and tstms. For more information about the wave, refer to the section above. Otherwise, the southwestern periphery of the Azores high continue to tighten the pressure gradient in the south-central basin, thus supporting fresh winds between 65W and 83W. Strong to near-gale winds are forecast at night along the Colombia coast and adjacent waters. No major changes expected through early next week. ATLANTIC OCEAN... Mid to upper-level diffluent flow between a ridge in the west Atlantic and a trough along the E CONUS continue to support scattered showers and tstms N of 25N W of 70W. The remainder basin is under the influence of the Azores high, which is anchored by a 1036 mb high near 40N37W. Fair weather is elsewhere, however hazy conditions are expected S of 26N as an extensive Saharan Air Layer outbreak moves across the Atlantic tropical waters. For additional information please visit http://www.hurricanes.gov/marine $$ ERA