No, the Outdoor Warning Sirens aren’t just for tornados, they are all-hazard which means they can be sounded for several types of severe weather criteria, as well other emergency situations as deemed necessary by the Office of Emergency Management.

What are the criteria for siren activation?

The City of Carrollton Office of Emergency Management operates the Outdoor Warning Siren System in accordance with the North Central Texas Outdoor Warning Siren Framework.

This document and a list of participating cities can be found on the website of the North Central Texas Council of Governments website: North Central Texas Council of Governments - Outdoor Warning Sirens (nctcog.org). To view the actual Framework document, click on “Outdoor Warning System Framework” above the list of participating jurisdictions. This non-binding Framework leaves the final decision on activating the siren during any specific circumstance to the local emergency manager.

However, in an effort to provide a general consensus on siren activation throughout the North Texas Region and to assist our media partners in explaining why a jurisdiction is activating sirens, the Framework recognizes the below criteria for siren activation:

1. The National Weather Service issues a Tornado Warning for areas in and around the City of Carrollton.
   
   
2. Trained storm spotters have reported a tornado in the City of Carrollton, or in a neighboring jurisdiction with the potential to affect the City of Carrollton.
   
   
3. The National Weather Service issues a Severe Thunderstorm Warning with the possibility of damaging winds in excess of 70 mph for areas in and around the City of Carrollton, and such wind speeds have been confirmed on the ground and/or produced damage. 
   
   
4. Observed hail of 1.5" in diameter or greater (size may be adjusted for areas or events where large numbers of people are outdoors or based on time of day).
   
   
5. Other emergency situations as deemed necessary by the Office of Emergency Management.

Will sirens always be activated any time one of the severe weather criteria (tornado, wind, hail) is met?

The siren system will always be activated in the event of a tornado threat to the City, regardless of time of day. However Emergency Management Staff in Carrollton uses discretion and may not activate the sirens for hail and high winds during the overnight hours. This is because sirens are meant to be heard outdoors only, and to alert people to go inside and seek more information.

If most people are already in their homes late at night, they are already where they need to be for high winds and hail. Activating the sirens might bring more people outside to look at what is going on rather than sending people inside where they are safe. During a tornado warning we need people to be in their tornado safe room in their house. If we can wake a few people up and get them to safety, that is what we want to do.

This type of flexibility in activating the sirens for non-tornadic severe weather threats is allowed under the Regional Outdoor Warning System Framework, and is critical to ensuing our emergency management staff has the discretion to do what is deemed best for the residents of Carrollton in any one circumstance.

The Outdoor Warning Siren system is tested at 1:00 PM on the first Wednesday of every month.

Regular monthly testing is critical to maintaining the performance of the siren system, so our philosophy is to test unless there is a valid reason not to. The test may proceed under mostly cloudy skies, as long as there is no rain or severe weather in the forecast.

The test will be cancelled if there are rain showers or storms in the area, or if severe weather is in the forecast for later that day.  

No, the siren system is designed to be heard only by those outdoors. This is because the construction of many buildings can make it difficult for the sound of the siren to penetrate inside the structure.

After all, we don’t want to be kept awake inside our houses by the sounds of cars and other things outside!

Many other factors can also affect whether a siren is heard in one specific spot at a specific time, such as the topography of surrounding structures and landscape and even the temperature, humidity of the air, and direction of the wind.

So, with all of these factors, the siren system is meant only to alert those outdoors that they need to go indoors.

Go inside a sturdy structure immediately and seek more information from radio, television or other sources such as the City's social media feeds on the nature of the threat and the action to take.

If you are already inside and are able to hear the sirens, DO NOT go outside to look around!

Will the sirens be activated constantly while there is a threat?

No. Carrollton’s siren system is battery powered via solar panels, so we are careful to manage use to ensure sirens can be activated multiple time in between charging opportunities.

Since each real activation of the sirens runs for three minutes, our procedure is to wait for five minutes after the first activation ends and then reassess the threat.

If the threat persists, we will sound the siren again, and repeat this pattern until the threat has passed.

Typical tornado warning events, for example, require us to activate the siren system two to three times.

When you activate the sirens, do you have to turn them all on, or can you turn only some of them on?

We can activate all twenty-six sirens throughout the City at once if we need to, however we can also activate the sirens just by County as well.  

The City of Carrollton resides in three Counties (Dallas, Denton, and a small portion of Collin County). This is important, as we have seen many instances where the National Weather Service will issue a warning based on the county lines, so either the Dallas County portion of Carrollton is under the warning but the Denton County section is not, or vice versa.

In these cases, we activate the sirens only in the portion of the City in the affected County in an effort to avoid over warning. We can also activate the sirens by quadrant (based on George Bush going east and west and Josey Lane going north and south), or individually if needed for a more localized event.

The system is configured this way to allow for maximum flexibility in warning our residents and to avoid disturbing those who do not need to be warned.

Do the sirens have different tones for different threats?

No, the sirens have only one tone: a steady wail. The sirens do rotate however, so the wail will rise and fall as the siren spins.

There is no all-clear siren signal. If you hear the sirens going off that means there is still a threat in the area.

If there is no all clear signal and there can be periods of quiet between activations, how do I know when the threat has passed and it is safe to come out of my safe place?

You should always keep a battery powered  weather radio or a standard AM/FM radio in your safe place. Use this to monitor the situation and to learn when the threat has passed and it is safe to come out.

Why do I hear sirens when there is nothing from the City about them being activated on social media?

The cities bordering Carrollton also have siren systems and can be heard far into Carrollton, depending upon weather and wind conditions. Examples are the City of Dallas, Addison, Farmers Branch, Irving, Coppell, Lewisville, The Colony, and Plano.

There have been many times when one of these cities activated their sirens for a threat facing them, but Carrollton did not need to activate.

The best way to see if the sirens you are hearing are Carrollton’s is to monitor the City’s social media accounts and webpage. Siren activations are published as quickly as possible during emergency situations.

What should I do if the City said the sirens went off near me but I didn’t hear anything, or I noticed that a siren near me that worked before is definitely not working now?

If you know the Carrollton Outdoor Warning Siren system was activated and you did not hear it (outdoors, not indoors), please let the City know as soon as possible so the issue can be investigated and maintenance performed if needed.

The best way to notify the City is by calling the City of Carrollton Resolution Center at 972-466-3000 during regular business hours.

 
Part of Carrollton was included in a Severe Thunderstorm or Tornado Warning box issued by the National Weather Service (NWS), why did/didn't you activate the sirens?

Often times the National Weather Service will issue a tornado or severe thunderstorm warning box that contains only a small portion of Carrollton, or the box is overdrawn for a large part of the DFW area to be safe but it is clear the main threat will not affect Carrollton.

• In these cases, the City's Emergency Management staff communicates directly with the National Weather Service forecast desk to determine if any part of Carrollton is truly in the threatened area.
  
  
• If the threat is clearly going to miss the City, staff may hold off on siren activation, even if part of the City is technically within the warning box.
  
  
• It's possible a resident may receive an alert on their phone or by other news methods that they are within a warned area, but not hear the sirens.
  
  
• The warnings that come to your phone or other mobile devices are triggered only by whether or not your current location is within the warning box issued by the NWS.
  
  
• Staff will always err on the side of caution when a threat is near the City, but if our partners at the NWS confirm it will miss us, we also want to be responsible in our non-use of warning systems so as to avoid the “cry wolf” effect as much as possible.

There were high winds in excess of 70 mph and/or large hail over 1.5”, why didn’t the sirens go off?

This is especially common at night. If it is overnight, City staff likely will not sound sirens for hail or high winds as specified in the North Texas Siren Framework. This is an example of the authority of each local jurisdictions to adjust the criteria based on their own specific philosophy and needs.

In order to be safe from high winds and hail, residents typically just need to be indoors, not in a tornado safe place. So if most people are already indoors at night or early morning, we judge that we are likely to get more people going outside to see why the sirens are going off at that time of day then we are to get to go indoors.

Sirens will always be sounded for a tornado threat however, regardless of time of day.