The General Use of Outdoor Warning Siren Systems for Severe Weather: A National Survey of Emergency Managers

Outdoor warning siren systems are used to warn on a variety of threats, but exactly how and when sirens are used varies widely among jurisdictions. To better understand how siren systems are used for weather warning applications, an on-line survey developed by the authors was distributed by the International Association of Emergency Managers (IAEM) to its membership in fall 2012. A total of 383 respondents completed the 31 question survey.

Survey results showed that a large majority (71%) of emergency managers (EMs) operate siren systems with three-quarters of EMs utilizing additional warning systems. The siren policy for warning on weather-related hazards varies widely among jurisdictions, with over 90% warning on tornadoes, 38% for severe winds and 21% for hail. Specific criteria for warning on wind and hail vary by jurisdiction. Nearly half (47.1%) of EMs also warn on non-weather hazardous events. Local decision-making plays a significant role when sounding the sirens; of those EMs who regularly sound sirens for tornadoes, 30% may choose not to sound the sirens during a National Weather Service (NWS) Tornado Warning. Nearly half of EMs (45.5%) may activate sirens before a NWS warning is issued. Nearly two-thirds (65.4%) of EMs have the ability to sound subsections of their siren network, and nearly the same percentage (62.7%) have multiple sound options available on at least some part of their siren network. Overall, the policy, application and operation of outdoor warning siren systems are complex, with local systems designed and used for warning on only the greatest threats to the immediate area.