Hereâs why I chose the NASM certification! Did you need any sort of background related to the field going into the program? Nope, you just need to make sure that you have a current CPR and AED certification before you take the exam. How long does your certification last before you have to renew it?
Tornado Warning. This is issued when a tornado is indicated by the WSR-88D radar or sighted by spotters; therefore, people in the affected area should seek safe shelter immediately. They can be issued without a Tornado Watch being already in effect. They are usually issued for a duration of around 30 minutes.
The Tornado Watch. 1  Meteorologists using the latest in computers, radar and satellite data are always monitoring the weather elements. When a high probability of severe weather exists, a tornado or severe thunderstorm watch is issued. Watches may be issued hours before any severe storm hits the area.