As a student I would view snow days as a time to forget about school. As a teacher I would view them as a big disruptor that would cause me to lose the flow of learning and would delay the next activity, whether it was a test or a project. While students easily can see if school is cancelled or not, it used to be very hard to get information out to them about how class would be affected. That has changed thanks to 1:1 programs and various tools that can increase communication between teachers and students.
If your school is a GAFE school, like Ames is, then all of your students already have email addresses that you have access to. It becomes easy to set up a Google Group for your class so you can send out a quick email to everyone at once. The only issue becomes if the student checks their email or not which could easily be avoided if there is a class norm about checking emails on snow days. You could tell students how the schedule would be affected and even give them resources to work on.
A class website becomes a great tool to communicate with students and even parents. While this is mostly a 1 way communication, it can be a tool that allows you to easily show the schedule changes, embed a Google Calendar, and post resources, such as a Google Doc or link to an outside site. The key is to make sure the class website is used regularly in your class, the regular use will increase the effectiveness of the tool.
I used to tell my students to check my Twitter feed for updates to class, either by following me on Twitter or by going to my site where I embedded a Twitter feed. This allowed me to send updates no matter where I was and the 140 characters was all I needed for most days. This also allowed for 2 way communication if the student was also on Twitter and conversations could happen even if we were not in school.
This is a tool that I wish I had known more about when I had students. https://www.remind101.com/ allows you to easily send text messages to students and/or parents without having to know their phone numbers. A teacher sets up their account and the students or parents will sign in and submit their number to the system, not to the teacher. A group is created and the teacher can easily send out updates to everyone that needs it. With a very large number of students having cell phones, this can allow you to easily connect with them in an instant. There will be no lost time in class if updates are sent out on time.
No matter what tool you use, you can easily keep the learning on track and avoid disruptions by using a tool to communicate with students when the schedule changes. These tools can also be useful for extending the learning beyond the 45 minutes, or so, that you get each day. Communication is key for effective learning and we have so many tools available to us today to ensure that we are communicating effectively and efficiently.