Emergency Management

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Warning Sirens

The Outdoor Warning Siren System (OWSS) is an outdoor, all-hazards siren system that is used to warn the general population of a potential danger in a short amount of time. The system is designed to provide coverage to persons out of doors, not inside buildings or structures.

What Do the Sirens Mean?

  • The OWSS will be activated upon receipt of a tornado warning issued by the National Weather Service (NWS) for 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).

Siren Test

Please note that cities do perform a monthly siren test to ensure all sirens are functioning. The entire system is tested at noon on the first Saturday of each month unless severe weather is imminent.

What Should I Do if I Hear the Sirens?

If the sirens are activated – and it is not a monthly test – the public should see it as a signal to:

  • Seek shelter
  • Tune into radio or television to get information about:
    • Type of Emergency
    • Instructions & Recommendations

The public should not call 9-1-1 unless they have an actual emergency.

Contact Us

Polk County Emergency Management
1907 Carpenter Avenue
Des Moines, IA 50314
(515) 286-2107

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