986 AXNT20 KNHC 231656 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 1256 PM EDT Thu Aug 23 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 1200 UTC surface analysis and satellite imagery through 1715 UTC. ...TROPICAL WAVES... An eastern Atlantic tropical wave has its axis along 32W from 04N-20N, moving westward at 15 kt. The wave is embedded within a very dry and stable environment which is inhibiting convection at this time. A central Atlantic tropical wave has its axis extending along 52W from 05N-20N, moving westward at 15-20 kt. This wave is also embedded within a very dry and stable environment caused by Saharan Air Layer outbreak of the past several days that is spreading westward across the central and eastern Atlantic. Scattered showers are noted south of 10N where the wave meets the ITCZ. An central Caribbean Sea tropical wave has its axis along 75W south of 20N to north Colombia. It is moving westward at 20 kt. No significant convection is observed within this wave at this time. A tropical wave has its axis along 88W south of 19N, moving westward near 20 kt. Scattered showers are within 120 nm of the wave axis. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from the African coast near 12N17W to 08N22W to 10N40W to 09N51W. The ITCZ axis begins at 09N53W and continues to the coast of South America near 07N58W. Widely scattered moderate convection is from 05N-09N between 07W- 17W. Scattered showers are noted elsewhere within 180 nm either side of the monsoon trough and ITCZ. ...DISCUSSION... GULF OF MEXICO... A cold front is over the N Gulf of Mexico from 31N80W to 29N83W. A stationary front continues to 27N90W to 29N95W. A pre-frontal trough extends from N Florida near 29N82W to the NE Gulf near 26N86W. Widely scattered moderate convection is within 90 nm of the pre-frontal trough. A 1018 mb high is located over the northwest Gulf near 25N95W. Elsewhere, scattered showers are over the Bay of Campeche from 17N-20N between 93W-96W. The present pressure gradient across the Gulf supports light winds throughout, with a windshift along the frontal system. In the upper levels an upper level high centered over Texas near 32N99W is producing NE upper level winds over the Gulf with upper level moisture. Expect for the front to become quasi-stationary until Fri and dissipate on Sat. CARIBBEAN SEA... Two tropical waves are moving across the basin. Refer to the section above for details. An upper level low is centered over the Cayman Islands near 19N81W. The low is producing scattered showers near the upper low center and is enhancing convection over the SW Caribbean due to upper level diffluence. Scattered moderate to isolated strong convection is over the SW Caribbean S of 12N to include over Panama and Costa Rica. Elsewhere, scattered showers are over the SE Caribbean from 11N-15N between 61W-68W. Expect strong nocturnal pulses of winds through the upcoming weekend along the coast of NE Colombia and W Venezuela with seas building to 9 ft. ATLANTIC OCEAN... Two tropical waves are moving across the basin. Refer to the section above for details. A cold front is off the coast of N Florida from 32N79W to 31N80W. Widely scattered moderate convection is from 27N-32N west of 75W. Scattered showers are over the west Atlantic from 25N-29N between 65W-72W due to an upper level low centered near 26N72W. A surface trough extends over the central Atlantic from 27N57W to 19N58W. Scattered showwers are within 120 nm of the trough. A 1024 mb high is analyzed near 37N51W. Saharan dust and associated dry air, although not as dense as in previous days, is noted mainly east of about 60W on GOES-16 GEO color dust imagery. The dust is keeping convection limited to non- existent across the eastern and central Atlantic waters. For additional information please visit http://www.hurricanes.gov/marine $$ Formosa