The City of Duncan Outdoor Warning Siren System consists of 28 high power warning sirens in the city and a siren at each of the four city lakes. Please note that the lakes are now independent of each other for siren activation so a siren can be sounded individually or in a group of affected lakes.  These sirens are controlled via radio and are always in communication with the central siren computer located in Emergency Management’s Emergency Operations Center at City Hall. The system is designed to provide an automated warning to anyone in city limits that may be outdoors during the approach of severe weather. This includes tornado warning or high winds above 70 MPH. It is important to note that these sirens are meant for outdoor warning and depending on your proximity to a siren, may not be heard indoors. The use of weather warning applications on your smart phone and/or NOAA Weather Radio (tune to 162.550 MHZ) are recommended for indoor warning.  

Residents may sign up for Duncan Alert Emergency Notifications. This system will notify subscribers of severe weather and other local emergencies by sending a text or voice call to your provided phone number. You may visit https://www.duncanok.gov/244/Emergency-Notifications to sign yourself up for Duncan Alert Emergency Notifications or call 580 251-7757 to be added to the list.

Redundant severe weather warning capability is recommended by the National Weather Service to keep you informed in a weather emergency! 

How Do These Sirens Work and When Are They Activated

70+ MPH Wind or Tornado Warning:

When a Tornado Warning is issued by the National Weather Service that affects the city limits of Duncan and/or Duncan lakes, the city sirens and/or lake sirens are automatically activated by the central siren computer in the Emergency Operations Center. The sirens will sound a wailing sound which rises and falls in pitch for a period of three minutes. When this sound is heard, you should seek tornado shelter immediately. If you wish further information, check your local media sources (example: kswo.com), NOAA.gov, local radio stations, or NOAA Weather Radio (tune to 162.550MHZ). 

Please do not call 911 unless you have an emergency to report. 

Additionally, the Emergency Management Emergency Operations Center will also sound the Outdoor Warning Siren System for radar indicated winds over 70 MPH or if trained weather spotters spot a tornado. If possible, 15 minutes of warning time will be provided. 

The signal for Tornado Warning is a rise and fall in pitch for a period of three minutes. 

The system may sound a tornado warning signal multiple times before or during an emergency. 

A few things to Note: 

Sirens will sound in city limits for a warning that affects any portion of the city limits. Do not depend solely on any mechanical or electronic device to provide lifesaving warning. Always be weather aware and keep yourself informed. Severe weather can occur without warning and before a warning can be issued to the public in time. 

All-Clear:

When the emergency is clear of the area and no longer poses a threat to the city or city lakes, the All-Clear signal is sounded. This is a steady pitch sound that is sounded for three minutes. This signal is sounded to alert those in a shelter that it is safe to exit. Before exiting your shelter, ensure the signal you have heard is a steady signal for three minutes and not an additional tornado warning signal. 

The signal for All Clear is a contact pitch for three minutes.

Siren Testing

Keeping the siren system operational is a top priority of the Emergency Management team. 

Daily testing by the central siren computer in the EOC takes place three times a day and is completely silent. The tests check the siren system for proper voltages, charging, radio comms, and more to ensure the siren is ready for activation. Realtime siren status are displayed on a computer screen in the EOC and is also accessible remotely at any time. 

Weekly testing of the siren system is fully automated. Weather depending, each lake siren is activated sequentially beginning at 11:59 a.m. every Monday. The City of Duncan sirens will follow at noon. This audible test is canceled in the event severe weather is expected and a silent test is done instead.

For the audible test, the computer runs an abbreviated testing sequence consisting of 1.5 minutes of All-Clear followed by 1.5 minutes of the warning signal. Substitutions may be considered if additional tests are required. 

The system monitors siren voltage and current, battery levels, rotation, charger status, line voltage and communications strength. These conditions are communicated back to the central activation point and relayed to the Emergency Management Director for immediate maintenance or repair, if needed. 

Audible tests are important to ensure the system is working properly. During audible testing, the battery back-up is tested to ensure proper power is available to sound the system for multiple warnings. During the test, residents should recognize and understand the different siren signals, listen to audio levels for their location, and familiarize themselves with their specific tornado shelter plan of action. 

 Remember:

 The signal for Tornado Warning is a rise and fall in pitch for a period of three minutes. 

The signal for All Clear is a contact pitch for three minutes.

It is important to note that these sirens rotate and project sound 365 degrees. The volume of the siren varies with the direction the siren is pointing during this rotation. It is not the volume of the siren that indicates the signal. It is the pitch of the siren sound.

Additional Warning Capability

Lightning Warning:

Automated Lightning Detection and Warning has been implemented at Abe Raizen and Jess Welch Sports Complex, Fuqua Park West, and the Simmons Center (locations at additional City of Duncan parks, City of Duncan area lakes, and Heritage Trails are planned to have this capability in future). These lightning warning sirens sound a distinct hi-low tone and then broadcast a voice message: "Lightning Warning. Cloud to ground lighting is expected in the area. Seek shelter.”  Voice instructions are given to take shelter indoors. Indication of approaching lightning is made from a central lightning detector. Lightning within a 10-mile radius can strike in city limits. Therefore, lightning 10 miles or closer activates the lightning warning siren. Take shelter even if the sky seems clear. Lightning is dangerous. If you hear thunder, go indoors. Wait 30 minutes after the last lightning strike before resuming outdoor activity. Lightning sirens do not activate between the hours of 11 p.m. and 6 a.m. to mirror the city ordinance for park operation hours.

ALWAYS BE WEATHER AWARE DUNCAN!

If you have any questions, please call City of Duncan Emergency Management at 580 251-7757 or email: EMDUNCAN@duncanok.gov