Montgomery County, MD has a great service that notifies you about school closings, severe weather, and other emergencies. It is called Alert Montgomery and it can send the alert to you through email, text message, or pager (I can't recall the last time I saw someone with a pager). It is very customizable too, there are around a dozen categories of alerts with many options within them. For instance, I have signed up to receive alerts for severe weather, rush hour traffic, police alerts for my district and school closings. If you have kids in a public school you can sign up for alerts for that specific school as well.
If you are not into email they are active on twitter and facebook too.