According to a Hennepin County press release:
Storm warning sirens in some of the hardest-hit areas of Hennepin County may be without power after a series of storms in recent days.
As more severe weather may be approaching over the next 48 hours, all metro-area residents are urged to use multiple information sources to monitor weather conditions.
Though sirens are intended to provide outdoor warning, no single warning source will work in all emergency circumstances. People should always have several
methods to obtain warning information. In the Twin Cities metro area, local radio stations (830 WCCO AM, and. 91.1 MPR FM) are excellent sources; so are all of the local broadcast television stations (Channels 4,5,9 and 11). Cellular phones/smart device applications also provide good warning if cell towers are operable. Find resources at www.weather.gov/subscribe.
As of midday Saturday, county officials estimated that at least one-fourth of cities in Hennepin County may have at least a few sirens off-line due to power issues. Actual numbers of inoperable sirens were not available. However, the
county had received no reports of sirens damaged or destroyed by the storm. Many sirens in damaged areas are up and running using generator power from the facility where they are located, or using solar or battery power.
In Hennepin County and for most metro counties, sirens are sounded for tornado warnings and for straight-line winds at or above 70 MPH. Friday night’s storm had
gusts of more than 60 miles per hour.
About 70 percent of Hennepin County is covered by Outdoor Warning Sirens. The rural west and northwest portion of the county is not well covered by sirens.
Sirens are purchased, owned and maintained by cities and special jurisdictions. The county activates sirens using weather triggers from the National Weather Service.
The current siren system dates back to the Cold War. Though cities are replacing systems at an increasing rate over the past few years, some currently used sirens were installed in the 1950s.
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