AWNS monitors the National Weather Service for severe weather statements. As they are issued they are sent to a listproc mailing list based on the the NWS office that issued the statement. This provides a proactive notification system to alert the public on severe weather events. AWNS was just recently upgraded to begin coverage of the US! Checkout the AWNS homepage for more details, progress of project, and how to subscribe.
“Automated Weather Notification System,” ibiblio catalog, accessed November 30, 2015, http://www.ibiblio.org/catalog/items/show/3692.