That's plotted at 57 lat, -4 lon using 1x1 degree GEFS data. Not sure about the altitude but remember that quite a big area is covered.
The snow row is calculated by looking at all of the individual runs at all of the timesteps. For example take Day 2:
There are 4 time steps, 00, 06, 12, 18
If GEFS P5 is the only run to show snow but shows it more than one time step (e.g. 06 and 18) the snow row value will be one.
If GEFS P5 and P10 show snow for one time step each on the same day (e.g. P5 06, P10 18) the snow row value will be two.
Originally Posted by: Brian Gaze