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OEM Completes Upgrades to the Tornado Warning System

7/1/2020
Joseph Pleasant; Public Information Officer

New Polygonal Alerting Tornado Siren System is fully operational

The Nashville Office of Emergency Management in conjunction with Federal Signal, Commtech Radio and Metro Information Technology Services completed upgrades to the existing Tornado Warning System.

The new Tornado Warning System will operate on a Polygonal Alert model. This model will provide warnings to a focused polygonal alert area based on information coming directly from the National Weather Service.

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

However, the growl test scheduled for the third (3rd) Monday of every month will be discontinued. If there is a test of the system outside of the regularly scheduled test OEM will notify the public.

The upgraded Polygonal Alerting Tornado Siren System cost about $2.1 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.

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

Tornado Warning Siren