- The OWSS will be activated upon receipt of a tornado warning issued by the National Weather Service (NWS) in Polk County.
- Severe Thunderstorm Warnings where forecasted or actual wind speeds reach or exceed 70mph (61kts)
- Sirens will sound in a cycle of 3-5 minutes, followed by a 10-15-minute break for the duration of the threat (warning period).
Please note that cities do perform a monthly siren test to ensure all sirens are functioning. The entire system is tested at one p.m. on the first Saturday of each month unless severe weather is imminent.