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.
Report Abuse. A tornado watch means that conditions are favorable for a tornado to form. When a tornado watch is issued, you are often advised to stay tuned to your local news or weather station, just in case the watch is updated to a warning. They are preparing you for any tornado that forms. simsfan41 Â· 5 years ago.