This link is a blog from the Rolla Police Chief relating to the Rolla area tornado from December 31, 2010.
http://rollacity.blogspot.com/2011/01/police-chief-chat.html

This is a web site from the city of Rolla about their procedure for setting off sirens. It also has information about tornadoes.
http://www.rollacity.org/emergency/emergency.pdf

This web site is from NOAA and is about using cell phones to warn people about tornadoes.
 http://www.nws.noaa.gov/com/weatherreadynation/wea.html#.UlLG0RrnaJl

David