In the case of Mayfield, some of the answers seem to be: 1. Quite extreme. NWS had been highlighting the potential for a significant outbreak of severe weather

In the case of Mayfield, some of the answers seem to be: 1. Quite extreme. NWS had been highlighting the potential for a significant outbreak of severe weather for at least a day at that point. My local WFO (KIND) referred to the system’s potential as “exceptionally dangerous,” which is not language that NWS forecasters use haphazardly. 2. Mayfield had over 2.5 hours of warning from KPAH.[0] I’ve noted elsewhere that this tweet wasn’t a formal warning, of course, but it was a strong heads-up that something big was in the offing. At the very least, local emergency managers should have been aware of this and monitoring the situation very closely. 3. The tweets from KPAH regarding the storm and naming Mayfield specifically were pretty strong. Add to this the actual warnings themselves, which were Particularly Dangerous Situation warnings. A Tornado Emergency warning was also issued as it became clear Mayfield was in the crosshairs. Those are the strongest warnings in the NWS’s arsenal. The first tornado warning on that cell was issued around 6pm CST, and the tornado almost immediately became destructive. Forecasters knew that the cell was entering a convective environment that was highly conducive for the cell to persist and even strengthen. (The various Mesoscale Discussions that the SPC issued for this cell make that clear.) So, between that knowledge and the track that the cell was on, KPAH was able to determine that Mayfield was in serious danger hours beforehand. So, the possibility at least existed that plant managers could have known what was coming. One question might be what the local emergency management agency did to disseminate these warnings to the community. Most people, unless they’re weather nerds, probably aren’t reading mesoscale discussions from SPC or forecast discussions and tweets from their local WFO. But I’d expect emergency management to be doing so and then making determinations about how to respond to that information. So, it’s hard to say precisely how much plant managers knew, but it’s possible that they could have known well ahead of time. It’s also possible that they believed it to be more prudent to keep people in the plant rather than sending them home to structures that may well have been much less sturdy. [0] See https://cliffmass.blogspot.com/2021/12/a-critical-gap-in-tornado-warning.html?m=1 https://cliffmass.blogspot.com/2021/12/a-critical-gap-in-tor...