864 AXNT20 KNHC 201339 AAA TWDAT Tropical Weather Discussion...Updated NWS National Hurricane Center Miami FL 939 AM EDT Mon Aug 20 2018 Updated Caribbean Sea section 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 1315 UTC. ...TROPICAL WAVES... A far eastern Atlantic tropical wave has its axis along 32W/33W from 05N to 17N, moving westward at 10-15 kt. Isolated moderate convection is from 05N to 17N. Scattered moderate convection is within 180 nm east of the wave from 05N to 08N. Isolated showers and thunderstorms are elsewhere within 180 nm either side of the wave from 05N to 11N. A central Atlantic tropical wave has its axis extending from 05N51W to 12N50.5W to 18N49W, moving westward at 10-15 kt. Isolated showers and thunderstorms are within 120 nm either side of the wave from 08N to 11N. A Caribbean Sea tropical wave has its axis extending from far southern Costa Rica northward to 15N77W and to eastern Cuba near 20N76W. It is moving westward at 10-15 kt. Isolated moderate convection is within 60 nm east of the wave from 20N-21N. The northern portion of an eastern Pacific tropical wave extends along 91W northward to the far eastern Bay of Campeche, moving westward near 15 kt. Only isolated showers are noted within 60 nm of the wave. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from western Africa at 13N17W to 10N28W to 08N40W, where scatterometer data indicates the ITCZ axis begins and extends to 08N49W where it briefly ends just east to the east of the central Atlantic tropical wave. It resumes at 09N52W to just inland the coast of S America at 07N58W. Scattered moderate convection is within 60 nm south of the axis between 17W and 20W. Widely scattered moderate convection is seen from 05N to 09N between 26W and 29W. Isolated moderate convection is within 60 nm of the ITCZ axis between 53W and 58W. ...DISCUSSION... GULF OF MEXICO... A 1023 mb high is centered over the W Atlantic at 32N59W, with a ridge axis extending WSW from the high to central Florida and to the eastern gulf waters. The associated gradient is allowing for generally moderate southerly flow to persist over much of the gulf, except for lighter SW to W flow, in the 5-10 kt range over the far northeastern gulf waters. Widely scattered moderate convection is over the N Florida Peninsula N of 27N. The northern portion of a tropical wave is over the eastern Bay of Campeche. No deep convection is occurring with this wave. See above for details. Scattered moderate to isolated strong convection is from 15N to 21N between 92W and 95W. A small upper-level low is centered over the Yucatan Channel near 22N86W enhancing the convection over western Cuba and the NW Caribbean Sea. Expect, a surface high to develop over the Gulf near 27N91W on Tue. This high will meander over the western gulf waters through Thu. A weak trough will stalls over the eastern Gulf waters, then drifts west and dissipates on Fri. CARIBBEAN SEA...Updated A tropical wave is over the western section of the central Caribbean. See above for details. A surface trough has recently become evident roughly along a position from 18N69W to near 20N72W. Latest satellite imagery shows an area of increasing scattered moderate convection within 60 nm east of the trough from 15N to 17N. This activity is being further aided by an upper-level disturbance that is quickly moving westward in moderate to strong east winds that are located to the south of an upper anticyclone centered just north of the Dominican Republic. Otherwise, surface ridging extending from the Atlantic to the northern half of the basin support fresh to strong winds in the south-central Caribbean. Expect scattered shower showers and convection to persist over the southwestern Caribbean through at least Wed. Also expect strong to near gale force nocturnal easterly trades expected along the northwestern coast of Colombia and across the Gulf of Venezuela through the middle of the week. ATLANTIC OCEAN... A surface trough is analyzed from near 32N51W to 28N62W. Another surface trough is analyzed from near 32N45W to 22N55W. Meanwhile, a small upper-level low is near 28N62W. The combination of a very moist and unstable atmosphere and upper divergence to the east and southeast of the low is leading to scattered moderate convection from 25N-29N between 61W and 65W. Isolated showers and thunderstorms are seen within 60 nm south of the first trough between 57W and 62W. Yet another surface trough is analyzed along a position from near 28N69W to the southeastern Bahamas near 22N74W. A shortwave trough passing just to its northwest is providing additional atmospheric lift leading to clusters of scattered moderate convection from 26N to 29N and between 71W and 74W. Isolated showers and thunderstorms are elsewhere within 90 nm of the surface trough from 22N to 26N. The trough from 28N69W to the southeastern Bahamas is forecast to move westward across the Bahamas through Wed. An upper-level anticyclone is identified to be just north of the Dominican Republic near 21N70W. Its associated subsidence is suppressing deep convection from developing in that general area, however, a narrow band of broken to overcast low and mid-level clouds with scattered showers and isolated thunderstorms is noted from just along the coast of Hispaniola northward to 21N and between 69W and 72W. E of the lower Windward Islands, scattered moderate convection is seen within 30 nm either side of a line from 09N58W to 11N61W. A 1023 mb high is centered over the western Atlantic near 32N59W. A 1026 mb high is centered to the southwest of the Azores near 37N31W. It is allowing for ridging and generally fair weather to persist over the eastern Atlantic. The trough north of the central Bahamas is forecast to move westward across the Bahamas through Tue night. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre