Iowa Weather: Explaining outdoor warning sirens
Many Iowans have heard the blaring tones of storm sirens recently, thanks to numerous rounds of severe storms.
Sirens have been a staple of the severe weather warning system for decades, but there are many misconceptions about them.
They're not designed to warn people indoors
Sirens are not meant to be heard inside homes, businesses and other buildings. They're specifically called "outdoor warning sirens."
Sirens' purpose are to alert people outside that dangerous weather is imminent, allowing them to get indoors and find more information about the threat.
Sirens aren't just for tornadoes
Warning sirens have long been associated with tornadoes, but they often go off for other types of severe weather.
Many cities and counties also sound their sirens for damaging straight-line winds and very large hail.
The Iowa Emergency Management Association actually recommends sirens be activated if a storm could produce wind gusts above 70 mph or hail larger that 1.75 inches in diameter (golf-ball size).
Because of this, even certain severe thunderstorm warnings can leading to sirens sounding.
Siren policies vary place to place
In Iowa, local jurisdictions like cities and counties activate outdoor warning sirens.
This means a severe storm might trigger sirens in one community, but not another, just because they have different policies.
Some siren systems also sound countywide, even when only part of the county is threatened by tornadoes, wind, or hail.
To learn more about your area's outdoor warning siren guidelines, contact your county emergency management.