After the sky turned orange in New Zealand a few days ago from the smoke from the Australian bushfires [1], I stumbled across this blog post by Scott Bachmeier:
The post contains relevant satellite imagery taken from Himiwari-8 showing the creation of pyrocumulonimbus clouds from the fires, along with thermal imaging. There is also a technical explanation about how the thermal anomalies are detected.
The smoke cloud is now heading to the middle of pacific ocean and is still visible from space [2]