085 AXNT20 KNHC 260604 TWDAT Tropical Weather Discussion NWS National Hurricane Center Miami FL 204 AM EDT Sun Aug 26 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 0545 UTC. ...TROPICAL WAVES... A far eastern Atlantic tropical wave has its axis along 28W from 05N to 20N, moving westward at 15 kt. Scattered moderate convection is within 30 nm of line from 12N28W to 11N34W, and within 30 nm of line from 06N26W to 05N28W to 04N32W. Isolated showers are elsewhere from 10N to 13N between 27W and 30W. Another eastern Atlantic tropical wave has its axis along 38W/39W from 04N to 20N, moving westward at 10-15 kt. Broken to overcast multilayer clouds along with scattered moderate isolated strong convection are noted where the wave axis crosses the monsoon trough, and to the south of the monsoon trough. The scattered moderate isolated strong convection is occurring from 05N to 07N between 35W and 37W. Scattered moderate isolated strong convection is within 30 nm of line from 11N34W to 11N38W, and within 30 nm of line from 11N39W to 11N44W. Scattered showers and isolated thunderstorms are seen along the monsoon trough within 120 nm east of the wave. A central Atlantic tropical wave has its axis along 55W from 03N to 19N, moving westward at 15 kt. Isolated showers and thunderstorms are within 60 nm either side of the wave south of 08N. A central Caribbean Sea tropical wave has its axis along 72W south of 19N to well inland S America, moving westward at 10-15 kt. Rather dry and stable conditions surround this wave. Isolated showers moving quickly westward are possible near this wave. ...MONSOON TROUGH/ITCZ... The monsoon trough axis extends from coast of Senegal near 14N17W, to 10N23W, 09N30W, 08N36W, and 07N39W. The ITCZ continues from 07N39W to 05N45W and 05N50W. Aside from convection associated with the tropical waves, increasing scattered moderate isolated strong convection is south of the trough axis within 30 nm of a line from 06N12W to 07N20W to 07N26W, and also within 60 nm of 08N145W. ...DISCUSSION... GULF OF MEXICO... A narrow NE-to-SW oriented upper-level trough extends from 32N81W near the South Carolina/ Georgia border, across NE Florida, to 28N83W in the NE corner of the Gulf of Mexico, to 23N88W in the Gulf of Mexico. An inverted mid/upper-level trough progressing westward at 15-20 kt is along a position from near 30N85W to 25N87W and to near 23N88.5W. A surface trough is analyzed from 29N84W to 24N85W. Latest radar and satellite imagery show scattered showers and thunderstorms covering over much of the waters east of 88W. Isolated showers and thunderstorms are noted between 88W and 96W. Weak high pressure exists over the area. A surface trough will develop during the evening hours in the Yucatan Peninsula, before pushing offshore into the SW corner of the Gulf of Mexico each night. A surge of moderate to fresh NE to E winds will accompany this trough. High pressure will continue across the remainder of the area, supporting a gentle to moderate wind flow. CARIBBEAN SEA... An upper-level trough extends from an upper low near 22N62W southwestward to near 20N64W, then becomes a shear axis to another upper-level low at 15N71W. Lack of deep level moisture over the eastern and central Caribbean is only allowing for isolated showers to persist there in the easterly flow. A rather weak upper-level low is over the far southwestern Caribbean near 12N77W. Scattered showers and thunderstorms are seen south of 14N and west of 77W. A very moist and unstable atmospheric environment present over the remainder of the western Caribbean is conducive for sustaining scattered shower and thunderstorm activity as well as for additional ones to form there into the upcoming week. Scattered showers and thunderstorms over and near the Windward Passage will continue through at least tonight under, with support from upper-level disturbances that are rotating in a cyclonic fashion around an upper-level low centered between the central Bahamas and Cuba. Fresh to strong winds and building seas to 10 ft will prevail in the south-central Caribbean Sea through Wed. The tropical wave along 72W will move across the rest of the central Caribbean through Mon evening, and across the western Caribbean Tue through Wed night. Another tropical wave is forecast to approach the Lesser Antilles on Tue and Tue night, and enter the eastern Caribbean on Wed. This wave is forecast to be accompanied by scattered to numerous showers and thunderstorms, some of which may produce gusty winds and rough seas. ATLANTIC OCEAN... An upper-level cyclonic circulation center is identified on water vapor imagery to be between the central and Cuba near 23N77W, moving westward. A second cyclonic circulation center is near 28N67W. A surface trough, clearly noted in scatterometer pass from last night, is analyzed from near 27N70W to just north of Haiti at 20N72W. Gentle to moderate winds are being produced by the gradient associated with this trough. Instability provided by these features on an already very moist and unstable atmosphere is allowing for scattered showers and thunderstorms to continue over the waters west of 65W, with the most concentrated activity present from 24N to 27N between 69W and 73W. Scattered showers and isolated thunderstorms are seen from 24N to 26N between 68W and 71W due to an upper-level disturbance moving westward around the southwestern periphery of an upper-level ridge that extends from an upper anticyclone that is near 31N60W. Isolated showers are elsewhere west of 70W. The surface trough is forecast to move across western half of the area through Mon. An upper-level trough extends from an upper-level cyclonic circulation center near 33N18W to another upper-level cyclonic circulation near 30N46W. The trough continues to a third cyclonic upper-level circulation center near 22N62W and southwestward from there to near 20N64W. A surface trough is along a position from 31N43W to 29N50W. Scattered showers and thunderstorms are seen from 29N to 31N between 42W and 49W. Isolated showers, moving quickly westward, are elsewhere between 42W and 70W. Winds will pulse to fresh to strong during the evening and nighttime hours between the southeastern Bahamas and Hispaniola through the middle of next week. A surface ridge will dominate the rest of the forecast area, supporting a gentle to moderate anticyclonic flow. For additional information please visit http://www.hurricanes.gov/marine $$ Aguirre