Most districts build in a couple of snow days into the schedule, so if they need to use them like tomorrow, they can just count one of those days and then go later on in the year when those days pop up on the schedule.
Remember all most all districts these days are counting hours of seat time, not days in the classroom, this switch gave them a lot of flexibility to work around snow days. Schools on 4-day school weeks might be stressed more, but many if they miss tomorrow will just go on Friday, if that is the day, they are taking off now.