Tornado by American Red Cross is a complete resource for tracking tornadoes in your area and learning what to do when a tornado warning is issued. You can set up notifications when tornado alerts are issued for various locations, and you can view the historical patterns of tornadoes in your area.
I'm safe message: This app gives you the ability to customize a message to send to your friends and family to let them know you're safe if a tornado does strike your area. When you set this up ahead of time, you can let everyone know at once via email, SMS, Facebook, or Twitter, and set their minds at ease quickly. Add a personalized message if you choose to, and then add specific recipients from your contact list, or just post your message directly to one of the social networks supported.
Creating a plan: The app also walks you through the process of making an emergency plan for your family, so everyone knows what to do and where to go if a tornado warning is issued or if a tornado actually strikes your area. With this feature, you can add each of your family members, assign them specific responsibilities, and select meeting points where you can regroup, if you become separated at any point.
NOAA optimization: This app includes a link to the NOAA Weather page, which provides live streaming weather reports and access to weather cams from various locations. But the page is not optimized for mobile devices, which can make it a little difficult to navigate, especially if you're in a hurry.
If you live in an area that's often visited by tornadoes, or if you have friends or family who do, this app is an excellent resource. It provides everything you need to know about tornadoes all in one place, and its intuitive interface makes it easy to find critical information in an emergency.