796 AGXX40 KNHC 300713 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 313 AM EDT Mon Jul 30 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 surface ridge extends across the basin, anchored by a 1030 mb high center located over the north-central Atlantic. The associated gradient is allowing for anticyclonic winds with speeds in the 5-10 kt range to exist over most of the forecast waters. Observed waveheights are rather low, 1-2 ft throughout, except for slightly higher seas of 2-3 ft in the southwestern section of the gulf. A dissipating stationary front is draped from the far western Florida panhandle to across southern Louisiana and the Florida Panhandle. A surface trough is over the southeastern gulf waters extending from just south of Fort Myers, Florida southwest to 25N83W and to 23N86W, while a small upper-level low is seen near 26N86W. With plenty of deep moisture in place for these features to work with, the end result is a continuation of scattered showers and thunderstorms to plague just about the entire eastern part of the gulf south of 30N. Scattered showers and weakening thunderstorms are quickly moving southeastward over Louisiana. Similar activity is over the western half of the Yucatan Peninsula and its immediate adjacent coast S of 21N. Weak high pressure will prevail across the area through the week. Models indicate that a cold front. supported by strong upper level troughing for this time of year, will approach the northwestern gulf waters Tue, and move across those waters Wed. The front will lift back N to over eastern Texas as a warm front on Wed night, then push eastward over the NW 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... Central Atlantic high pressure ridging has poked southwestward to the NW Caribbean as a tropical wave has its axis near 76W as of 06Z. This wave will move across the rest of the central Caribbean through this evening and across the western Caribbean tonight. Another tropical wave is moving across the Lesser Antilles early this morning. This wave will move across the eastern Caribbean through early Tue, then across the central Caribbean later on Tue through Tue night, and the western Caribbean Wed through Thu night. The upper-level synoptic set-up that consists of the combination of a large upper-level low presently located over the Windward Passage and that is slowly migrating westward, along with a narrow N to S oriented ridge just to its west, is acting to provide a diffluent flow pattern over the north-central Caribbean. The present deep- layer moisture available there is bringing scattered to showers and thunderstorms to much of the waters north of 19N and west of 75W. As the aforementioned tropical waves pass through the western section of the central Caribbean and through the western Caribbean during the next few days, expect for a good likelihood that additional shower and thunderstorm activity, assisted by the upper-level environment, to develop over those same waters Otherwise, the pressure gradient between strong central Atlantic high pressure and broad low pressure over northern Colombia and the far southwestern Caribbean will maintain strong northeast to east winds along the coast of NW Colombia and NW Venezuela each night through Tue night, then mainly fresh winds with locally strong winds on Wed. Northeast to east winds are pulsing to near gale force along the coast of Colombia and to within 90 nm of that coast early this morning, but are forecast to diminish to just below gale force at or near 15Z this morning. These winds are then forecast to pulse back up to near gale force tonight and Tue night as passage of the waves across the central Caribbean will help enhance the gradient further to induce the northeast to east trades to reach near gale force along the coast of Colombia and over the far southwestern Caribbean waters. Fresh trade winds will prevail elsewhere across the central Caribbean, with moderate to fresh east winds over the eastern Caribbean, and gentle to moderate east-southeast winds over the western Caribbean. East winds will pulse to strong intensity over the Gulf of Honduras at night through Thu. ...SW N ATLANTIC INCLUDING THE BAHAMAS... Ample atmospheric deep layer moisture is entrenched over the western section of the forecast waters. The combination of a deep layer trough over the southeastern United States and this moisture will continue to set the stage for scattered to numerous showers and thunderstorms to remain quite active over waters west of about 76W. This activity is progged by moisture guidance from the models to continue into the Wed time frame. A large upper-level low, the same feature described above under Caribbean Sea and tropical N Atlantic, is noted over the Windward Passage. The bulk of its associated shower and thunderstorm activity is over the northwestern and N central Caribbean waters. Only isolated showers and thunderstorms are seen along and near the coast of Hispaniola north to near 25N and between 67W-73W. This activity is moving to the northwest. This activity will continue in the general direction of the Bahamas through Wed. High pressure ridging from the central Atlantic will extend to central Florida through Tue before lifting north of 31N by Thu. Fresh to occasionally strong east winds are expected just N of Hispaniola through Fri. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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.