998 AGXX40 KNHC 310752 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 352 AM EDT Tue Jul 31 2018 Marine Weather Discussion for the Gulf of Mexico, Caribbean Sea, and Tropical North Atlantic from 07N to 19N between 55W and 64W and the Southwest North Atlantic including the Bahamas ...GULF OF MEXICO... A weak surface ridge extends into the eastern Gulf from the western Atlantic. With a rather weak pressure gradient in place resultant winds are in the gentle to moderate range across the basin, except for possible higher winds in the fresh to strong range over the far eastern part of the eastern Bay of Campeche along the immediate Yucatan Peninsula coast due to nocturnal scattered moderate convection along and inland the Yucatan Peninsula. An upper trough that extends from near 30N88W to 25N90W and to a small upper- level low at 21N95W is helping to enhance the atmospheric instability across the eastern half of the gulf, which is resulting in scattered showers and isolated thunderstorms across those waters. Little change is expected with this pattern through at least Fri. Winds across the area will change little in speeds through Sat, with the exception of the far eastern part of the eastern Bay of Campeche where the gradient will be the strongest in association with the typical thermal trough that emerges off the Yucatan Peninsula during the evening hours and moves across eastern Bay of Campeche during the mornings and dissipates near 94W by early in the afternoon. Weak high pressure will prevail across the area through Sat. A cold front will approach the NW gulf waters Tue, and move across those waters Wed. The front will stall late Wed then push eastward over the northern gulf waters as a weakening trough on Thu. Scattered showers and thunderstorms, with possible brief gusty winds and slightly higher seas are expected along and near the front and trough. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... A tropical wave with its axis along 70W is moving westward at 15-20 kt. The wave is to the SE of a large upper-level low that is observed to be just south of eastern Cuba. This juxtaposition places the wave in a favorable setting for active convection to occur to the east and southeast of the low. Latest satellite imagery shows scattered moderate convection west of the wave from 15N-16N. The wave will move across the rest of the central Caribbean through early tonight, and across the western Caribbean Wed through Wed night. The next tropical wave will move across the eastern section of the tropical N Atlantic zones this evening, then across the remainder of the those waters through Wed evening. It is forecast to move across the eastern Caribbean Thu through Fri and across the central Caribbean Fri night through Sat night. A batch of scattered showers and isolated thunderstorms is most probable to precede the wave by about 240 nm and south of about 15N as it moves through the tropical N Atlantic waters and the eastern section of the Caribbean. Over the southwestern Caribbean, pulses of deep convection will continue through the rest of the week as the eastern extent eastern of the NE Pacific monsoon trough axis protrudes into that part of the sea. The Bermuda high northeast of the Caribbean in combination with low pressure over the southwestern Caribbean and Colombia are contributing toward a moderate pressure gradient over the Caribbean. Strong to near gale-force northeast to east winds are pulsing along the coast of Colombia N of 11N and along the NW Venezuela coast. These winds will diminish to mainly strong winds this morning. Strong winds will pulse over the Gulf Honduras each night through Sat. Elsewhere, fresh trades will prevail across the central Caribbean, with moderate to fresh trades over the eastern Caribbean, and gentle to moderate trades over the western Caribbean. ...SW N ATLANTIC INCLUDING THE BAHAMAS... The main issue over the these waters continues to be the shower and thunderstorm activity that is occurring over the western half of the basin west of about 76W. This activity is being fueled by plenty of atmospheric instability that has been in place there for several days along with ample deep moisture. As a large upper-level low, currently centered just south of eastern Cuba, migrates further westward during the next couple of days, expect for a pocket of some dry and sinking air that precedes it to halt the aforementioned convection from developing less in coverage as compared to that of the past several days. Otherwise, strong central Atlantic high pressure extending to central Florida will lift just north of the area on Wed. Fresh to occasionally strong east winds are expected to continue to pulse from the afternoon hours and through the overnight hours over the waters between the SE Bahamas and Hispaniola through Sat. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *For detailed zone descriptions, please visit: http://www.nhc.noaa.gov/abouttafbprod.shtml#OWF Note: gridded marine forecasts are available in the National Digital Forecast Database (NDFD) at: http://www.nhc.noaa.gov/marine/grids.php For additional information, please visit: http://www.nhc.noaa.gov/marine $$ .Forecaster Aguirre. National Hurricane Center.