When rain is predicted, the rain-barrel observers start asking me questions. The containers work best when all the barrels and buckets have rainwater to share before the storm.
At 4 AM Charlie wanted to go out but not too long. We kept hearing rumbling but no rain. That arrived at 7 AM, and now the backyard is a lake again.
The timing was perfect for the backyard because we have so many barrels and buckets. That gives the roses a good start for the rain and fresh nitrogenated water for the next round.
My mother never let the teachers in on the alternative solution - let the chlorinated water from the school evaporate the chlorine in the pitcher for one day. Flowers would rather have de-chlorinated (that is, unbleached) plants. They thrive.