I run our risk management work team in our department in the local government I work at.
A couple things we do, visible lightning is a shutdown, but 15 minutes is not safe, 30 is the national weather service reccomended interval. Talent goes in a trailer or building, public is told to return to vehicles and wait it out.
We have a 60% (I think, I would have to check the paperwork) threshold on our stages. Whatever the engineered max wind speed is, we evacuate if there is a gust up to 60% of max. Also we monitor weather service and a warning with Mac winds at 60% of threshold is grounds for evac.
Any tent over an 8x8 popup has to have a wind rating reported by the supplier, we use the same thresholds for that.
Power is pretty constant for us, so we just meter to check, but if it was a new connection, has to be a real disconnect, no sister lugs. Connected equipment must have a breaker not over rating of connecting cable. (We won't connect your dimmer rack with a 400a breaker to our 400a disconnect with anything less that 0000 for example.
Crowd control is not usually a concern at our events.
For our outdoor shows (that we produce), if weather is questionable, we try to make a call at noon on day of show. We usually talk to a meteorologist at the weather service we use, to check our assumptions and reading of the forecast. If it is likely it will rain, we postpone or cancel for free outdoor concerts.