Outdoor warning sirens - part 1: the role of the EMA during severe weather

Recently I had the honor and pleasure of sitting down with several individuals from the Memphis/Shelby County Emergency Management Agency (MSCEMA), including Mr. Bob Nations, Director; Mr. Levell Blanchard, Deputy Director; Mr. Tommy Thompson, Outdoor Warning Siren Coordinator; and Mr. Keith Butler, Dispatcher and "technical guy" for the EMA's many electronics and communications systems.  I also was fortunate to tour the EMA's Emergency Operations Center in Midtown. The purpose of the meeting was to discuss the outdoor warning siren system in Shelby County, learn more about how their systems and processes work during severe weather, and perhaps find out if any changes to the warning process were in the works.  I came away impressed with both the responsibility and recent accomplishments of the EMA personnel.

This is the first in a 3-part blog series on the outdoor warning sirens in Shelby County.  This first entry examines the role of the EMA during severe weather, including the sounding of the sirens.  The second installment will focus on the intent of outdoor warning sirens, what they are designed to do, and NOT to do. The answers may surprise you. We'll conclude with a look at the future of warning technology, including sirens, in part 3.

Photo credit:
MSCEMA.org

One of the most visible (or audible perhaps) roles of the EMA is the sounding of outdoor warning sirens. I've discussed the policy of sounding the sirens previously on this blog, but the bottom line is this: currently, all sirens in Shelby County sound continuously throughout the duration of a Tornado Warning if any part of Shelby County is included in a National Weather Service-issued Tornado Warning.  That means if Millington is under a tornado warning, Collierville's sirens sound (more on how this works below).  Click here for a map of siren locations in Shelby County or click here for a list of all sirens..

Though the siren system was originally designed to warn the public of air raids during World War II, then nuclear fallout during the Cold War, the practice of using sirens to warn of severe weather dates back decades, well before the NWS began issuing polygon warnings that didn't encompass entire counties. That NWS policy change occurred in 2007.

The EMA Emergency Operations Center (EOC) is staffed by dispatchers around-the-clock, handling all sorts of calls for emergency response.  Their busiest period is typically during severe weather. In the EOC, a computer running weather messaging software is constantly ingesting bulletins from the Memphis NWS office via satellite (with internet backup) and processing them for any watches and warnings.  (Backup systems are also in place in case of a failure of the primary computer, including Weather Radio, statewide emergency communications, and local broadcast television.)  In the event of a watch or warning, a pop-up on the dispatcher's terminal immediately displays the text of the alert.

Photo credit: metrolic.com

If the alert received by the dispatcher is a Tornado Warning for any part of Shelby County, the dispatcher will then activate the sirens throughout Shelby County - except Bartlett, Collierville, and Germantown - using two different systems.  The three municipalities named are responsible for activation of the sirens in their own jurisdictions. Telephone calls are placed from EMA to dispatchers in each of these three suburban cities to make them aware of the warning.  Bartlett, Collierville, and Germantown will typically also sound their sirens based on the information they receive.  The sirens sound countywide until the expiration time of the warning or the cancellation of it, should the NWS cancel the warning prior to the original expiration time.  All of Shelby County must be clear of any Tornado Warnings before the sirens will be shut off.

Stay with us later this week as we examine the use of outdoor sirens in part 2 of this 3-part blog series.

----
For weather information for Memphis and the Mid-South, where and when you need it, visit MemphisWeather.net on the web, m.memphisweather.net on your mobile phone, download our iPhone or Android apps, or visit us on Facebook or Twitter.