GRIB (GRIdded Binary) is a mathematically concise data format commonly used in meteorology to store historical and forecast weather data.
If you have access to a reasonable broadband link (e.g. wifi in a marina) the easiest way to view grib files is to get them from US Grib, who also providefree viewer software. Even a chart covering 7 days ahead at 6 hour intervals is very small.
Where data volume is expensive, Mailasailand Saildocscan download almost the same data at about one tenth of the data volume. By reducing the area covered, some of the European weather charts we have used needed only 23 kb. The data can be displayed in a grib reader or (as in my case) on an electronic chart such as Software on Board which has the capability to interpret grib files. This data also looks 7 days ahead.
If you need a high quality synoptic chart, then both Mailasail and Saildocs can generate many types. The Mailasail selection is listed here. The example in the gallery is the forecast for a moment in time, but it has the advantage that the location of fronts is clearly shown.
Saildocs has the great advantage that you can ‘order’ a specific grib or chart to be delivered each day into the future (or for a specified time period). But it is a bit harder to set up.