High resolution weather files like you've never seen

We explain what GRIBs are plus why ProGRIB files represent the latest innovation in this technology
Above: a typical medium resolution GRIB file For some readers the term ‘GRIB’ will be as familiar as ‘mainsail’ or ‘tiller’, while we suspect for others it would be considered at best something one leaves to Steve Hayles, at worst a type of bug that lives on wood. In fact GRIB is a format of weather file (it is a abbreviation of GRIdded Binary) and the very latest incarnation using this technology looks set to revolutionise our forecasting be it for the America’s Cup, the Route du Rhum or even the most modest local dinghy club weekend race. This new technology provides very much more detailed information with, it is said, up to 30% better forecasts being produced even in comparison to the previous highest resolution models and with an interface so straightforward it can be easily picked up by even the most computer-phobic. So what exactly is a GRIB? Around the world, but mainly in North America, liquid nitrogen-cooled supercomputers whirr night and day number crunching what are known as ‘models’, enormous, highly complex simulation programs used to predict the weather. There are several variations in these models - some global, some more localised and all offering very different resolutions to the data they produce. A problem for the designers of models is the format in which to output the huge quantity of data resulting each time a model is ‘run’. One solution, conjured up by the World Meteorological Organisation in 1985, is the ‘GRIB’ file format, one of the rawest outputs of a weather model. For the more technically minded, it is a lengthy string of binary data, each segment containing the three dimensional location (lat, long and altitude) of a particular point, at a particular time, and a value for the particular piece of data in question