Dual tone Thunderbolt for a tornado warning:
http://youtube.com/watch?v=R2Iwrh3N8cU
Sickly STH-10 at Purdue, Thunderbolts and 2001's also heard:
http://youtube.com/watch?v=ibHWK-AFHbU
The STH-10 sounds really underpowered and slow. It has a great wind-down though.