We flew a trip from San Jose, California to Omaha, Nebraska during the worst of the fire season last year. We were at
FL390 in our Phenom 300, looking at a huge pyroclastic cumulonimbus that was building over the Rockies from a fire near Denver.
The Denver Center controller was amazed that jets in the high flight levels were diverting around this cloud, and he wanted to see pictures. He asked any pilots in the area to send him photos of the cloud, and he spelled out his FAA email address over the ARTCC frequency.
