Living in 42N country means coexisting with seasonal threats of tornadoes. This F1 rated tornado ripped the landscape between Center Point and Central City, Iowa on April 26, 2009 (photo courtesy of kcrg.com.) Part of the warning system for the county is the blaring of outdoor sirens placed in cities and rural areas. These sirens are activated by county officials and coordinated with the National Weather Service (generally from the Quad Cities) for the immediate 42N area.
If you live outside the Midwest here is what these sirens sound like once activated. This three minute recording was done in conjunction with the storm system that produced the tornado above last Sunday afternoon. While the pitch of the siren seems to change, it is due to the rotating horns that travel 360 degrees around the Y axis. A cool audio feature of the siren is the power down phase around 2:18 in the recording. Another more beneficial feature of the siren power down is an audible confirmation that the immediate threat is over.
5/6/2009 Update: In Linn County the sirens are controlled by risk managers associated with the Duane Arnold Power Plant (nuclear). The activation of the sirens can signal a variety of emergencies such as tornadoes, blizzards, nuclear, chemical, biological, or other severe weather. Once heard the listener should connect to local radio or television media to get the latest warning advice. Know that.