In the early news stories on the AF problem at Toronto yesterday, I heard one broadcaster say (approximately) "Pearson Airport was on Red Alert due to the severe weather, and no planes should have been allowed to land or take off due to the weather."

What exactly does "Red Alert" mean at an airport?

And if the airport weather was too risky, does anybody know why this flight wasn't diverted earlier on, before it may have been struck by lightning?

If the decision was made due to the cost of diversion, I hope in the future the folks in charge will more carefully weigh the cost of diverting against the cost of an Airbus A340 and 309 human lives.