Gray shade is from wildfire smoke
The site below gives us a forecast for the smoke plume for the next 48 hours, constantly updated. Pretty cool, eh?
Skies today in Evansville, IN clearing behind this cold front with the drier air pouring in would ordinarily be a vivid blue, with very high visibilities. 10-15+ miles. The visibility right now is only 5 miles.
This is from wildfire smoke. The downstream smoke plume from the Alberta wildfires is traveling thousands of miles away from the source.
Of course it's being diluted and not causing air quality issues this far away but can still be tracked all the way to the Atlantic Ocean!
Current status. Use this site to get specific information about the wildfires in Alberta.