The outdoor warning sirens are one tool Dane County Emergency Management utilizes as part of our severe weather warning system. They are intended to be heard outside, and should not be relied upon to be heard inside a structure. Outdoor warning sirens should not be your primary source of alert for tornado warnings. Instead, NOAA weather radios, smart phone apps, and/or local broadcast media should be your primary sources of severe weather alerts.
If you hear an outdoor warning siren, refer to one of the previously mentioned severe weather alert sources to confirm the siren activation, and seek shelter immediately as appropriate. If you believe the siren has been activated in error based on the lack of supporting information from other severe weather alerting sources, please call 608-255-2345 option 6, and report the location of the siren.
In the event of a Tornado Warning, the siren activation is a three-minute steady tone. This also includes monthly tests. The sirens in the warning area will only sound once, at the onset of the warning, and no 'all clear' signal will be sent. Sirens are tested the first Wednesday of every month at approximately 12:00pm, weather permitting. Occasionally, a siren site will communicate an error message to the controlling software. When that happens, our siren repair contractor will conduct testing to troubleshoot the issue and administer repairs as necessary. This process may necessitate a brief audible test of the siren to confirm its operational status. Because of the urgent need for this testing, the very short duration of the audible test, and the intrusive nature of a large area notification, Dane County Emergency Management does not notify area residents prior to audible testing.
Dane County Emergency Management will not conduct testing during threatening weather or after dark. Please contact Dane County Emergency Management at 608-266-4330 during normal business hours if you have questions regarding this process.
There are 141 outdoor warning sirens in the Dane County system. The sirens are located in the most densely populated areas of the County. As the outdoor component of the warning system, the sirens have a very important role; they are an effective means of alerting people who are outside and within range.
Click on the map to see a larger version of the image.
The circles on the map indicated the estimated OUTDOOR effective range of the sirens. The ranges are shown for planning and comparison purposes only. These ranges do not necessarily represent the actual audibility of any given siren.
There are a number of factors that affect the range of the siren. First of these is sound output. Very simply, some sirens are designed to be louder than others. A louder siren will have a greater range.
Atmospheric conditions also affect siren range. Wind speed and direction, air stability, and relative humidity all affect the distance that the sound will travel. Your ability to hear the siren will change as these conditions change. It is very possible that from your location, in some cases you will be able to hear the siren, while in other cases, you won’t.
Topography and background noise levels will also affect your ability to hear the sirens. Hills, trees, and buildings can be barriers that block the sound. High background noise levels from highways or industrial areas can mask the sound of the siren. These conditions will effectively limit the warning range of the siren.
Even with these limitations, sirens can be a very effective source of warning, if you are outdoors and within range of the siren.
National Weather Service Storm-Based Warnings
The National Weather Service implemented Storm-Based Warnings in October of 2007. Prior to 2007, the National Weather Service issued and disseminated tornado, severe thunderstorm, and flood hazard warnings using geo-political (typically county) boundaries. Storm-based warnings are based on the threat area of the storm itself, which usually does not recognize county boundaries.
Storm-based warnings are a substantial improvement over the old, county-wide warning method. Storm-based warnings provide more specific information about the location of the severe storm and the direction it is tracking. It also reduces the likelihood of unnecessarily alarming those outside the threat area. Especially in geographically large counties like Dane County, by issuing warnings based on the specifics of the storm, the National Weather Service can substantially reduce the area being warned. Here is a link to a fact sheet with more information on storm-based warnings.
Storm-Based Siren Activation
Beginning in 2011, Dane County began a two year project to upgrade the outdoor warning siren control system in order to allow for storm-based activation of the County’s outdoor warning siren system. Storm-based activation was fully implemented in 2013. Following a quiet severe weather season in 2013, the storm-based activation of the sirens was first employed in June of 2014.
With storm-based siren activation, the only sirens sounded are those with warning coverage in the Tornado Warning area determined by the National Weather Service. This reduces the likelihood of needlessly alerting people that are not at risk, and also provides certainty that you are in the warning area when you hear the sirens.
A picture is worth 1,000 words. Below is a radar map view of the storm-based Tornado Warning issued by the National Weather Service on June 18, 2014 at 7:57 AM.
Below is a map showing the sirens selected for activation in the same storm-based Tornado Warning:
Should I be able to hear the outdoor warning sirens in my home or business?
Are the outdoor warning sirens sounded county-wide for a Tornado Warning?
Can the outdoor warning siren loudness be turned down for the monthly tests?
Does Dane County use different siren sounds for different types of warnings?
Does Dane County sound the outdoor warning sirens for an “All-Clear” after the threat has passed?
NO! The sirens are the OUTDOOR component of the warning system. The siren system is not designed to alert people who are indoors. The sound from the sirens simply does not penetrate into buildings such that the sirens would be a reliable means of indoor warning. This is especially true in buildings with closed windows and interior background sounds such as television, air conditioning, appliances, etc. If you are inside, with the windows closed, the TV on or the air conditioner running, you will probably not hear a siren if it sounds, even if you are within the effective outdoor range. If you are sleeping, an outdoor siren will probably not wake you up. You are setting yourself up for a potentially dangerous situation if you are relying solely on an outdoor siren as your only source of warning.
This is not a new phenomenon. To illustrate, in a 1956 report submitted to Congress, the Federal Civil Defense Administration, stated, “Although satisfactory outdoor warning devices may be installed, there is still the problem of how to warn people in homes and other buildings from which the outdoor devices may not be heard.”
Thankfully, indoor warning is no longer the technical problem it once was. There have been great advances in indoor and mobile warning since 1956. Dane County Emergency Management recommends that people take advantage of these advances (smart phone apps, NOAA weather radio, broadcast media) and have alternate, redundant means of receiving warning information.
The siren system is designed to notify people who are outdoors that they need to seek shelter immediately and refer to an alternate severe weather alerting resource (smart phone apps, NOAA weather radio, broadcast media) for detailed storm information.
The outdoor warning sirens are activated as a result of storm-based warnings issued by the National Weather Service. Each time a new tornado warning is issued for any part of Dane County, the sirens will sound in the warning area for one 3 minute, steady-tone cycle.
While the National Weather Service is responsible for issuing severe weather warnings, they do not decide when and how local siren systems will be activated. Dane County’s siren system is operated by the County, and County policies determine when and how the sirens will be activated (storm-based). The primary activation point of the siren system is the Dane County 911 Center, with backup capabilities in the Dane County Emergency Management office.
Dane County’s siren system is activated using a storm-based method. The sirens are not sounded countywide. With storm-based siren activation, the only sirens sounded are those with warning coverage in the Tornado Warning area determined by the National Weather Service. This reduces the likelihood of needlessly alerting people that are not at risk, and also provides certainty that you are in the warning area when you hear the sirens.
The sirens in Dane County are tested between noon and 12:05 on the first Wednesday of every month from March through November. The sirens are not tested in the winter months.
Unfortunately, no, the sirens cannot be turned down. The sirens are either on or off. They cannot be turned down or be made less intrusive for tests.
No, in all cases, the siren activation is a three-minute steady tone. This includes monthly tests and actual warning activations. A few communities in Dane County still use the siren for local purposes such as a noon whistle or fire calls. Those signals are different. In all cases, however, the warning signal is a three-minute steady tone.
No. The sirens in Dane County are never sounded for an “All-Clear.”
Don't wait for the sirens to sound. If you see severe weather or are warned by TV, radio or cell phone alert to take cover, do so immediately.
Yes, tornados can and occasionally do form before public warnings can be issued. In some cases, storm damage reports are the first indication that a tornado has developed. This is especially the case with weak, short-lived tornados. Tornados of this nature can be on the ground, potentially causing damage before the rotation is indicated on radar and before an official tornado warning is issued.
If you see a threatening storm – high wind, large hail, heavy rain, lightning – take shelter. Don’t wait for a warning to be issued. Sometimes, your own observation might be the first indication of hazardous weather.
Please contact Dane County Emergency Management if you have a question about the siren system that is not answered here.
