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OEM Begins Installing New Tornado Siren Sites

4/21/2020
Joseph Pleasant; Public Information Officer NFD/OEM

New Polygonal Alerting Tornado Siren System estimated to be completed in 2020

Starting this week both Federal Signal and Commtech Radio in conjunction with Metro Information Technology Services and Metro Office of Emergency Management will begin the next phase of upgrading Davidson County’s existing Tornado Warning System.

During this phase of the project 20 new Tornado Warning System siren sites will be added around Nashville/Davidson County.

Crews will install the new siren and then conduct a growl test to make sure the installation was successful. The public may hear these growl tests randomly around the county in the coming weeks as new siren sites are brought online.

The growl test will produce an audible sound for about 20 seconds or less. The testing will not activate all sirens, only the siren at the location crews are working.

During this upgrade process the sites will only be tested Monday through Friday if the weather is clear. Most Tornado Warning System Siren sites are at parks, schools and public venues, so the public should expect to hear these tests.

The public may hear multiple test-per site lasting 15 seconds.

If you hear a three-minute tone, tune into local media or radio to ensure there are no tornado warnings.

The regularly scheduled Tornado Warning System testing conducted monthly on the 1st Saturday of every month at noon will continue.

There is a second monthly test of the Tornado Warning System conduced on the 3rd Monday of the month at 7:00 a.m. that will also continue.

During the upgrade process OEM will continue to set off ALL Siren Sites throughout the county for tornado warnings.

After all existing sites are updated the twenty (20) new sirens will expand the coverage footprint into more rural areas of Davidson County, bringing the total to 113 sirens that will then provide a focused polygonal alert based on information from the National Weather Service.

This project is estimated to be completed in 2020.

Please note weather will also play a role in the completion of the upgrades.

The upgraded Polygonal Alerting Tornado Siren System is estimated to cost $1.9 Million and was funded by Metro Nashville Government in the current 4% budget.

Metro first installed Weather Warning sirens in 2003. At that time, weather warnings issued by the National Weather Service (NWS) were for an entire county. Weather forecasting technology has improved significantly since 2003.

Weather warnings are now issued to potentially impacted areas based on the observed track and speed of the storms, without regard to political or geographic boundaries.

These polygonal alerts are defined by boxes drawn on a map and should be familiar to everyone as the odd shapes shown on the radar screen during television weather warning broadcasts.

This upgrade when complete, will make the siren system capable of Polygonal Alerting, and will activate only the sirens located inside the warned area, instead of all sirens county wide.

The alerts will be immediate, and sirens will activate mere seconds after a warning has been issued by the NWS.

Tornado Warning System