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.
Sirens will be activated for: 1  A tornado warning issued by the National Weather Service. 2  Tornado or funnel cloud reported by a reliable source. 3  Sustained winds in excess of 60 mph. 4  Reports of hail larger than one inch. 5  Chemical spill emergency. 6  State or national emergency declared by the governor or president.