General Policy for Activating Outdoor Warning Siren Systems for Severe Weather: Survey of Emergency Managers

Abstract

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 online survey developed by the authors was distributed by the International Association of Emergency Managers (IAEM) to its membership in fall 2012. More than 500 respondents answered the 31 question survey. Survey results showed a wide disparity in siren policy for warning on weather-related hazards. Among jurisdictions with outdoor warning systems, more than 90% activate sirens for tornadoes, 38% sound sirens for severe winds, and 21% for hail. Specific criteria for warning on wind and hail vary by jurisdiction. Local decision making plays a significant role when sounding the sirens; of those emergency managers (EMs) who regularly sound sirens for tornadoes, 30% may choose not to sound sirens during a National Weather Service (NWS) tornado warning. Nearly half of EMs (45.5%) may activate sirens before an 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 for severe weather are complex, with local systems designed and used for warning on only the greatest threats to the immediate area.