It's the astronomers forecast. At a glance, it shows when it will be cloudy or clear for up to the next two days. It's a prediction of when Pleasant Hill Starlight Observatory, TN, will have good weather for astronomical observing.
The forecast data comes from those very cool guys at the Canadian Meteorological Center. CMC's numerical weather forecasts are unique because they are specifically designed for astronomers. But they have 763 forecast maps. It can be a chore to find the one you want.
So, I (Attilla Danko) wrote a script to generate the images like the one above which summarizes CMC's forecast images just for Pleasant Hill Starlight Observatory and the surroundings out to about 10 miles.
There are also clocks for 3308 other locations.
This is one of the net oddities that might be useful...
