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OEM Reviews Outdoor Tornado Warning Siren Malfunction for August 28, 2020

8/28/2020
Joseph Pleasant; Public Information Officer

Software malfunction caused Outdoor Tornado Warning Sirens to continue to sound after Tornado Warning expired.

The Nashville Office of Emergency Management reviewed the tornado siren system following the severe weather that moved through Davidson County Friday afternoon.

According to a review of the system, sirens in a polygonal area designated within a Tornado Warning area sounded at 12:47pm when the National Weather Service (NWS) issued the Tornado Warning.

The NWS terminated the Tornado Warning at 1:07 p.m.

The upgraded Polygonal Outdoor Tornado Warning Siren System is fully automated. The sirens are activated when the NWS issues a tornado warning. The system is designed to automatically terminate the sounding of the sirens when the NWS terminates a warning as it did on Friday afternoon.

However, a review found that a radio connection to 3 to 4 sirens in the warning area failed to shut off the sirens.

During that time the sirens continued a cycle of sounding for three minutes then having seven minutes of silence, before they sounded again.

OEM Dispatchers became aware the sirens were still sounding and began a manual override to deactivate the sirens.

Dispatchers were then able to manually shut of the sirens still sounding.

OEM is working with the NWS as well as the contractor that installed the upgraded system to address this issue to keep this type of malfunction from happening in the future.

OEM Completed Polygonal Outdoor Tornado Warning System in 2020.

The upgraded system included updating technology on 93 existing tornado sirens across Davidson County. OEM also added 20 new siren sites to expand the coverage footprint into more rural areas of Davidson County, bringing the total to 113 sirens.

The former Tornado Warning System operated with an all call warning system. That meant when one tornado siren activated because of a tornado warning all the sirens activated across the county despite where the specific tornado warning is identified in the county.

The upgraded Polygonal Alerting Tornado Siren System cost about $2.1 Million and was funded by Metro Nashville Government in the current 4% budget.

When the sirens are activated:

  1. Go inside and seek additional information on the weather via weather radio, local news etc.
  2. If you're in the path of the storm, go inside a sturdy building to the lowest level, away from exterior walls Stay away from windows.
  3. Cover your head
  4. If there is no building available, and the storm is on top of you, find a ditch or low-lying area
  5. Lay down and cover your head
  6. Wait until the storm passes, then go safely