000 AGXX40 KNHC 031828 MIMATS Marine Weather Discussion NWS National Hurricane Center Miami FL 228 PM EDT Tue Oct 3 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... A tight gradient remains in place between strong 1038 mb high pressure over New England and troughing over the northern Caribbean and southern Gulf. Recent scatterometer passes indicated a broad swath of strong to near gale force NE to E winds from the western Atlantic through the central Gulf. Concurrent altimeter satellite passes indicated seas near 11 ft north of the Yucatan Channel. The strong winds will persist through late week as low pressure now over the far SW Caribbean moves northward and approaches the southern Gulf. While there is a general consensus among various global models regarding the movement of this low into the Gulf, there remains some difference on exact placement and timing of the approaching low. The official forecast follows a slightly slower and more conservative ECMWF/UKMET approach showing the low pressure reaching the Yucatan peninsula Fri, then emerging into the south central Gulf Sat as a possible tropical cyclone. The GFS remains the most aggressive, indicating a stronger low farther north into the central Gulf by late Sat into Sun, with the ECMWF weaker and more to the southeast. At any rate, expect the eastern and central Gulf to remain active for the next several days. ...CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... An area of low pressure continues to become more organized over the far SW Caribbean. A recent scatterometer showed a closed low along the monsoon trough 12N82W, with a band forming farther to the east within 240 nm. A tropical wave reaching from Panama to Grand Cayman is moving across this area into Central America. An upper trough is expected to dig across Florida into the Yucatan peninsula through the next couple of days, providing exhaust to the thunderstorms brewing near the low pressure and allowing it to deepen as it moves northward to the Gulf of Honduras through Thu. The low is expected to pause briefly over the Gulf of Honduras, out of the way of the shear provided by the upper trough, then deepen further as it moves farther north Fri into Sat. Strong southerly winds and building seas will follow along with the low pressure over the western Gulf through Fri as it moves northward. ...SW N ATLANTIC INCLUDING THE BAHAMAS... The remnants of a front, now having more of the appearance of a shear line, persist from 27N65W to the central Bahamas. High pres continues to build down from the N and support strong near gale force NE to E flow to the N of this boundary, with mainly moderate easterly flow S of the boundary. A recent scatterometer indicate the strongest winds north of Grand Bahama Island toward Cape Canaveral. There are enough frequent gusts to gale force to justify a gale warning through tonight in this area, gradually diminishing to strong gradient flow early Wed. Seas are 8 to 13 ft N of the boundary, and 4 to 7 ft S of the boundary. Broad surface troughing is S of the boundary, extending from the central Bahamas to central Cuba. A broad area of scattered thunderstorms is ongoing from 22N to 25N between 60W and 77W. Little change in these marine conditions is likely through the middle part of the week. The trough will slowly shift to the NW and W approaching the Straits of Florida Wed. Weak low pressure may develop along the trough prior to it shifting westward, although model guidance varies with the development of a low. The feature will exit the area by Fri with weak ridging and a significantly weaker pres gradient left across the basin in its wake. The weak ridging currently looks to hold in place for the upcoming weekend, with much more tranquil marine conditions possible. $$ .WARNINGS...Any changes impacting coastal NWS offices will be coordinated through AWIPS II Collaboration Chat, or by telephone: .GULF OF MEXICO... None. .CARIBBEAN SEA AND TROPICAL N ATLANTIC FROM 07N TO 19N BETWEEN 55W AND 64W... None. .SW N ATLANTIC INCLUDING THE BAHAMAS... .AMZ111...ATLANTIC FROM 27N TO 31N W OF 77W... Gale Warning tonight. .AMZ113...ATLANTIC FROM 27N TO 31N BETWEEN 70W AND 77W... Gale Warning tonight. $$ *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 Christensen. National Hurricane Center.