GRIB Weather

GRIB (GRIdded Binary) is a concise data format commonly used in meteorology to disseminate forecast weather data. For sailing purposes the GRIBs are transmitted and received at sea. These GRIBs contain only small subset of surface data, usually winds (direction and wind speed), information about wave strength (proportional to significant wave height) and direction, surface pressure. The data is further reduced by providing its subset around the position of a Yacht.

What can I see?

A GRIB file contains forecast information for a set number of days.
It is possible to animate the weather data which shows how weather systems are developing

The speed dial allows the user to set the speed at which the Zeus unit will animate the GRIB file – time steps and duration vary depending on the source of your GRIB file. Along with the automated animation, you can use the time dial to Step through the file manually, viewing the forecast for a specific date and time.

As you move the cursor around the Chart you will see the wind speed, wind direction and barometric pressure values at the cursor point for the Current forecast time selected. The angle of the wind barb indicates the geographical wind direction from 0 to 359 degrees. wind speed is indicated by a combination of short barbs, long barbs and pennants at the end of the wind tail. See table above.

Where can I get GRIB Files?

GRIB files are widely available, and most standard-resolution data is free to the user with the exception of communication costs.

There are three basic ways to acquire a GRIB file; different methods are used by each provider:

• Website. Straightforward area List or interactive map tool to download the region you require.
• E-mail services. Developed to be very efficient on data use. The user sends an e-mail that contains specific codes for the data they require and receive an e-mail with GRIB file attachment in return – useful for smartphone use.
• PC-based client programs. These usually work in a very similar Way to a browser based tool, but with the the program installed there is less to download (only the GRIB file itself) so it's faster and saves on communication costs. Some client programs also include a compression tool to further save on data cost.