Aurora cloud files

Cloud cover for the Aurora world map, rebuilt from each new NOAA GFS run (every 6 hours).

• clouds/latest.json: the run and the files available.
• 0.25° grids, hourly, for the latitudes where aurora can be seen (80–35° N, 35–70° S).
• 1° global grids, every 3 hours.

Each file is a gzipped grid of effective cloud % (255 = unknown). It combines the low, mid and high cloud layers the way the Aurora watch app does.

Data: NOAA Global Forecast System (public domain), read from the NOAA Open Data Dissemination program on AWS. Not an official NOAA product.