When sirens sound, what do they mean?

Perhaps you heard the sirens wail in your local community Wednesday around 1 p.m. Most of us know that’s the monthly siren test conducted by most Minnesota counties and communities.

But did you know there are different policies on when to blow the sirens in different communities around Minnesota?

For example, several Twin Cities-area counties activate sirens for tornado warnings and or storms that produce 70 mph or great winds. Here’s information from the Ramsey County website.

For severe weather Ramsey County sirens are sounded for all tornado warnings and for severe thunderstorms with wind speeds of 70 or more miles per hour. 
 

Sirens sound for three minutes and then automatically turn off to preserve their batteries. If they sound again that means there is a new danger such as a second tornado warning. Sirens are never sounded for an "all clear." You must listen to the radio or TV to find out if it is safe outside.

Here’s information on Hennepin County from the Hennepin West Mesonet site.

The outdoor warning sirens in Hennepin County will be activated for tornado warnings, severe winds at or exceeding 70 mph, or other situations when people should shelter in place. When the outdoor warning sirens are activated, they are only activated in the areas/cities listed in the warning polygon that is provided by the National Weather Service.

Here’s is more information on sirens and severe weather from Hennipen West Mesonet.

Siren Basics

Outdoor Warning Sirens exist to warn you to take immediate life-saving action. Sirens are often your LAST official warning, coming only minutes before a violent storm hits.

You should understand that Outdoor Warning Sirens warn people who are OUTSIDE that there is immediate danger.  You must use other ways to get warning when you are inside structures. A good indoor alert system is a NOAA Weather Radio.

When you hear Outdoor Warning Sirens, it means that you should:

1. GET INSIDE

2. GET INFORMATION

GET INSIDE means find a sturdy shelter immediately. Go to the lowest level. Find a small room far away from outside windows. Get into a bathtub or other protective place like under a sturdy workbench. Protect your head with a helmet if you can.

GET INFORMATION means having a battery powered radio with you in your shelter. Special NOAA Weather Radios provide very accurate information.  Commercial broadcast stations such as WCCO AM (830) and KNOW FM (91.1) and local TV stations also provide vital information.

Tests

At 1:00 PM on the first Wednesday of each month many counties test the sirens with full sound. This is a good time to have a simple emergency drill at your work, school or residence. When you hear a siren test, at least take a moment to think about what you would do in an actual emergency at that moment.

Siren Tones

There are two different tones used by Outdoor Warning Sirens:

• Attack: The signal for enemy attack is a rising and falling tone heard for 3 minutes.

• Civil Emergency: The signal for a civil emergency (such as a tornado) is a steady wail heard for at least 3 minutes

Remember: Many sirens rotate when they sound. Do not confuse increasing and decreasing volume with rising and falling tone.

History

Many Outdoor Warning Sirens were originally installed in the 1950’s for warning of enemy attack during the Cold War. The first civilian use of these sirens in the Twin Cities was during the 1965 Tornado Outbreak.

To check the status of your local county siren policy, check out the menu on the West Hennepin Mesonet site.