Pottawattamie County Emergency Management
Tornado Siren Operations Policy
Authority to Activate Sirens
The National Weather Service (NWS) is the authorized agency to declare a "Tornado Warning". Upon notification (by the NWS) of a tornado warning, local public warning procedures must be immediately implemented. Additionally, local emergency service officials (i.e., local fire, EMS, city officials, law enforcement), after observing a lowering funnel cloud or tornado may request sirens be activated when prudent to warn the public.
(NOTE: Emergency Officials may also request siren activation for high wind events forecast to impact their area. Generally, this would occur when winds are reported and/or forecasted to reach 70 mph (61 knots). However, it is at the discretion of the local emergency official to determine activation parameters.)
When tornado warnings are issued, the 9-1-1 Center will immediately activate the community tornado sirens (for the communities in the warned area) they are charged with activating.
- When tornado warnings are issued in communities whose siren(s) are not activated by 9-1-1, the designated authority must immediately respond to their community's activation point to sound their siren(s) or activate remotely, as applicable.
- The standard "wail" tone signifies a tornado warning has been issued for the area or a tornado has been spotted in the area.
- The siren sounding shall last for three (3) minutes. Sirens should not sound for the entire warning period. This will lead to a desensitized public and cause damage to sirens.
- When sirens are sounded the public should seek shelter in a suitable building or area for their protection.
- The public should ensure they have direct access (in shelter) to AM/FM radio and/or television to keep updated on the situation.
- THERE IS NO SIREN SOUNDING TO COMMUNICATE AN "ALL-CLEAR" OR TORNADO WARNING EXPIRATION.
- The public will receive warning expiration notifications from local radio and television stations.
- Sirens should be sounded again under the following conditions:
a. The tornado warning is extended or re-issued.
b. A tornado is spotted or confirmed "on the ground" in the area.
c. The National Weather Service issues a "Tornado Emergency" for a community.