When you hear a siren, what does it mean?

Twin Cities “Integrated Warning Team” met Thursday in Minneapolis

Sirens sounded for different severe weather criteria in different metro communities

NOAA Weather Radio, TV, Radio, smart phones, calls & texts, sirens – all ways people receive and process severe weather information

47 years since the May 6, 1965 Twin Cities Tornado outbreak

(biggest outbreak in Twin Cities history)

40 to 50 years statistical evidence an outbreak like 1965 should occur in the metro every 40 to 50 years.

(Source: Dr. Kenny Blumenfeld, UM tornado researcher)

Translation – we’re due for another major tornado outbreak in the densly populated Twin Cities metro area.

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Twin Cities “Integrated Warning Team”

It was great to be a part of a meeting today for the Twin Cities “Integrated Warning Team.”

A group of fellow broadcast and NWS meteorologists, Homeland Security and metro emergency managers talked about how we can better warn the public in Minnesota and western Wisconsin when severe weather strikes.

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Integrated Warning Team meets Thursday.

Photo by Paul Huttner-MPR News

The meeting focused on several topics, but one that probably received the most discussion was sirens. Here’s a quick synopsis.

Siren Activation:

One of the more controversial and sometimes confusing methods of alerting for severe weather in Minnesota is sirens. When you hear a siren during severe weather, what does it mean?

I wish the answer was simple, but it’s not.

It turns out sirens are activated for different severe weather thresholds in the metro and Minnesota. Here are some facts you may not have know about sirens in the metro and Minnesota.

-Sirens are owned and operated by individual cities and counties, not by the National Weather Service.

-Individual cities and counties have different criteria for sounding sirens in severe weather

-Sirens may be sounded for tornado warnings for all or part of a county

(Hennepin County sounds sirens in 4 “zones”)

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Twin Cities siren zones map.Source: Twin Cities NWS

-Sirens are sounded for severe thunderstorm warnings in some counties

(Dakota County blows sirens for T-Storm and Tornado warnings)

-Sirens may be sounded on reports of damage, funnels, or even rotation, or for winds of 70 to 75 mph (even if no warning is issued at the time)

-Sirens are generally sounded for 3 minutes when severe weather is imminent or occurring

-There is no “all clear” siren – stay in shelter until you know the storm threat has passed

-Most sirens would break down if sounded for 20 minutes continuously

-Many sirens have no battery back up, if the power is cut, the sirens won’t work

-Sirens may sound for other emergencies; such as hazardous materials spills, nuclear incidents or even terrorist threats

-Sirens are actually quite expensive to purchase and maintain

My comments:

This is one of the biggest severe weather areas we need to improve in Minnesota. This “patchwork” of reasons for activating sires is outdated, inconsistent and confusing to the public during severe weather.

When a siren in Minnetonka has a different message for the public than a siren in Apple Valley, that creates a messaging problem in severe weather. I understand different communities have different reasons for sounding sirens, but I really think we need to put the public’s ability to understand what a siren means first.

My challenge to cities, counties and the State of Minnesota is to come up with a consistent threshold for activating sirens during severe weather, and to communicate that clearly to the public. I would be thrilled to participate in helping get the word out to Minnesotans that when the siren goes off, this is what it means.

Until that perfect world arrives, here are the main things you need to know about sirens when you hear them during severe weather.

-Sirens mean severe weather is imminent or already occurring. Take cover immediately, then seek additional information from radio, TV, smart phones etc.

-There is no “all clear” siren. The severe weather threat may not be over when the siren stops. Stay in your shelter until you know the threat is past.

-Remember sirens are designed as an outdoor warning system. You should plan ahead to get your severe weather information from NOAA Weather Radio, TV, Radio, smart phones or other sources. You should actively seek severe weather information once you hear there is a possible threat of severe weather (such as a severe weather watch) and not wait until you hear a siren or other “risk signal” to act.

Minnesotans are pretty weather savvy overall, and that’s a good thing. One of the sad lessons from the deadly Joplin tornado was that too many people waited too long…and ignored too many of these risk signals before taking life-saving action.

What you do hours before severe weather hits, and in the minutes and seconds before it hits you, can literally be the difference between life and death.


Seeley talks weather records and drought on this week’s Weather Talk:

Look for UM professor and MPR colleague Mark Seeley’s excellent “Weather Talk” blog on Fridays here on Updraft starting this week.

Here’s a quick preview of this week’s blog topics.


-New State Record Temperatures on April 1st and 2nd

-Soil Moisture Update

-Lake ice-out dates

-Weekly Weather potpourri

-MPR listener question

-Almanac for April 6th

-Past weather


Topic: More temperature records to start April

“Following a record-setting month of March, April started with some new high temperature records in the southwestern counties of Minnesota. On April 1st (April Fool’s Day) Marshall set a new record with 78 degrees F, Pipestone had a new record 81 degrees F, Sioux Falls, SD set a new record with 89 degrees F, and Luverne set a new state record with a high of 90 degrees F. April 2nd brought more records with highs of 80 degrees F at Lakefield, 84 degrees F at Sioux Falls and Worthington, 86 degrees F at Luverne, and a new statewide record of 88 degrees F at Pipestone. And on April 3rd new temperature records were set with 79 degrees F at Redwood Falls, 81 degrees F at Windom and Pipestone, and 82 degrees F at Lakefield. Temperatures in southern and western portions of the state are averaging 13-18 degrees F warmer than normal for the month of April so far.

April 2nd also brought a round of thunderstorms to the state, some bringing large hail (up to 3/4 inch diameter). A few observers reported 0.30 to 0.50 inches of rainfall

Topic: Soil moisture still short, but improving in some places

University of Minnesota Research and Outreach Centers monitor soil moisture conditions for Minnesota’s major crops. Last fall’s (2011) measurements made it obvious that soil moisture storage was well below normal going into the winter season. For many areas over winter and early spring precipitation has been inadequate to help fully restore soil moisture to near normal levels for the spring. At Lamberton the final measurements from last fall showed 2.95 inches of stored soil moisture in the top 5 feet of the soil profile. Measurements made earlier this week showed that the profile moisture content had only “improved” to 3.09 inches of stored moisture, still roughly 2.5 inches less than average for this time of year. Further much of this moisture lies well below 3 feet and is out of the reach of crop rooting systems early in the growing season. So additional spring rains in April and early May are needed to recharge the upper layers of the soil for good germination and early development of corn and soybean crops.

For some areas, over winter and early spring recharge has been helpful. For example, at Waseca the final soil moisture measurements from last fall showed 4.67 inches of available moisture in the top 5 feet of the soil profile. The measurements made earlier this week in the same soil showed 7.37 inches of available stored soil moisture, an increase of 2.70 inches. This recharge came primarily from the Leap Day storm (Feb 29) which dropped 1.96 inches of rain, and the mid-March rains (Mar 20-23) which infiltrated the soil as well. Though this measurement is still below normal for stored soil moisture this time of year, this level of moisture is adequate for starting the planting season with optimism in the Waseca area.

Topic: Notes on early ice-out dates for Minnesota lakes

We have spoken in recent years about the obvious trend in earlier ice-out dates on Minnesota lakes. This year a number of lakes with lengthy observation records saw their earliest ice-out in history. The list below is compiled by Pete Boulay of the MN-State Climatology Office:

Lake Name County New Record Old Record Period of Record


White Bear Lake Ramsey/Wash March 19, 2012 March 21, 2000 85 years

Minnewaska Pope March 21, 2012 March 23, 2000 107 years

Green Kandiohi March 20, 2012 March 22, 1987 83 years

Mille Lacs Mille Lacs March 26, 2012 April 2, 2000 56 years

Big Sandy Aitkin March 26, 2012 March 31, 2000 59 years

Bemidji Beltrami April 2, 2012 April 6, 2010 76 years

Leech St. Louis April 2, 2012 April 6, 2010 77 years

Vermilion St. Louis April 2, 2012 April 6, 2010 93 years

Perhaps the bill in the MN-Legislature to advance the date of the Fishing Opener to May 5th this year will provoke a movement to make a permanent change to an earlier date so there will be no more conflicts with Mother’s Day weekend.

Weekly Weather Potpourri:

Wednesday afternoon and evening brought 13 tornadoes to the Dallas-Fort Worth area of Texas, some that were large and destructive. Hundreds of homes and buildings were damaged, but no fatalities were reported thanks in part to timely warnings from the National Weather Service. Hail damaged more than 100 aircraft at the DFW Airport. It was the first outbreak of tornadoes this month, following 223 reports of tornadoes during March nationwide.”

Also, I hope you’ll listen in Friday morning on The Daily Circuit at 9am when I will visit with Kerri, Tom & Paul Douglas to talk more about Thursday’s “Integrated Warning

Team” meeting, the Texas tornadoes and more severe weather.


  • Ann

    I admit, whenever I hear a siren, I check my phone or computer to see if I’m in the “polygon” before I do anything else. I developed this habit because I’m usually *not* in the polygon and want to make sure I actually need disrupt whatever I’m doing and go downstairs.

    I typically keep a close eye on my phone or computer when severe weather is predicted or the sky looks stormy. Obviously, I’m a weather nerd, so I’m usually doing that anyway. 🙂

  • Steve Scott

    During a siren test there are two different types of tone patterns sounded for one minute each. The first is a continuous tone, this is called ‘alert’. The second is a wavering tone called ‘attack’. These tones date back to the implementation of Civil Defense protocols in the 1950s for natural disasters & the possibility of nuclear attack.

    Certain cities, such as St. Cloud use the attack cycle for actual warnings. Most, though use the alert cycle for any kind of warning. Most MN cities use sirens with rotating internal mechanisms & large projector horns to produce their signature tones. A handful of MN cities have purchased electronic sirens that are, more or less, high powered speaker systems that can sound vocal information.

    Knowing where your community’s sirens are located is important to the safety of you & your neighbors. Anytime a siren fails to activate for a test or weather warning, you should contact your city’s Emergency Management Coordinator. If you’re uncertain of how to contact this person, city hall is a good alternative.

  • CHS

    Not sure you’ll get this comment on-air today with Keri, but my 2 cents has been this: Living ‘near’ Dakota County has made the warning sirens entirely MEANINGLESS to my neighborhood. Dakota County maintains a siren on the border with St. Paul, and their policy of issuing county-wide severe thunderstorm warnings is major disservice to the residents of the West Side and Cherokee Park neighborhoods. After an entire summer of listening to the sirens sound for thunderstorms in Rosemount, no one cares anymore. I’d rather have no siren than what we have.

    I sincerely hope that through the efforts being discussed that a standardized approach to the warning sirens comes forth to bring some sanity to warning siren protocols.

  • Dan

    I check to see if it’s not 1 PM on the first Wednesday of the month and if I see any inclement weather. If it’s not Wednesday I (now know that) “sirens mean severe weather is imminent or already occurring. Take cover immediately, then seek additional information from radio, TV, smart phones etc.”

    Thank you.