000 AGXX40 KNHC 011856 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 256 PM EDT Fri Sep 1 2017 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... Harvey moving NNE through the TN Valley right now, and leaving a convergent band from Fl Panhandle to central Gulf. Fresh W flow associated with this band extends to AL and NW FL coasts with sea heights 4 ft or lower. Weak high pres generally prevails elsewhere across the basin. Two tropical waves, one across S central Mexico along about 99W/100W, and a second moving through the Gulf of Honduras, are providing moisture and instability for active precipitation in SW and SE parts of the basin, and this situation will continue tonight. High pressure will prevail across the N and NE Gulf through the weekend, while a trough develops in the western Gulf. An area of low pressure may form in the southwestern Gulf along the trough. Any amount of development of this system is expected to be slow to occur as the low moves northward slowly. Mild marine conditions expected otherwise through Sun. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... Weak high pres across the W Atlc just SW of Bermuda inducing just enough pres gradient across the basin to produce strong winds S of 13N off the coast of Colombia, with otherwise seasonally mild conditions across the basin. The weak ridge N of the area will support pulsing fresh to strong trade winds off the coast of northwest Venezuela and northeast Colombia each night through Mon. Seas will build to 6-8 ft toward the early morning hours with the strongest winds. Moderate to fresh winds are expected across the Gulf of Honduras at night through the forecast period. Gentle to moderate NE-E winds and seas in the 4-6 ft range will prevail across the Tropical N Atlantic waters through the upcoming weekend. Looking ahead: Hurricane Irma will approach the Tropical North Atlantic zone Mon and forecast to begin to veer WNW and across the Leewards Tue night and Wed likely as a major hurricane. It is possible that the Leeward Islands may be threatened by Irma and all interests should stay tuned to developing forecasts. ...SW N ATLANTIC INCLUDING THE BAHAMAS... The southeasternmost point of cold front reaches near 26N65W. Moderate to fresh winds are ahead of the front, and they have shifted NE of the offshore zones. N to NE swell from low that developed from PTC 10 is affecting most of area N through NE of Bahamas, and will build across the NE waters during the next 24-36 hrs. Weak high pressure will dominate the area through tonight while the front will wash out and leave a weak trough extending NE-to-SW across the N waters through the weekend, and drifting W. Moderate to fresh E trades will prevail S of 22N and into S Bahamas, while gentle to moderate winds will prevail elsewhere. Major hurricane Irma is expected to approach the Leewards Tue and current forecast has this major hurricane moving across the outer islands Tue night and Wed. Models continue to adjust, with EC showing little change in trajectory through Wed, but then after passing the NE Carib it now turns more NW and brushes SE Bahamas as it recurves sharply. This is more in line with recent runs of other global models. Confidence in forecast will increase if this change continues in future runs. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... None. $$ *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 MT. National Hurricane Center.