Maxiumum Wind-Hail Tag Line on Severe Thunderstorm Warnings - March 1

Beginning March 1, 2010, the NWS office in Riverton along with all NWS offices serving the central U.S. will be appending a tag line to severe thunderstorm warnings (CYSSVRRIW) and follow-up severe weather statements (CYSSVSRIW).

The tag line is a concise code which identifies maximum hail size and wind speed expected for a given warning. Inclusion of this information at the end of these products represents an effort to respond to partner requests from the emergency management community as well as several societal impact groups.

For instance, one specific application concerns the activation of emergency alert sirens. Local area sirens are typically alarmed for tornadoes only. Decoding this tag line will facilitate the capability for local area emergency managers to activate sirens for particularly dangerous severe thunderstorm events when conditions exceed user defined thresholds (for example, wind speeds greater than 90 mph).

The maximum wind-hail size tag line is an experiment which will be evaluated from March 1, 2010 through October 1, 2010. During this period, we encourage comments or suggestions for improvement using the electronic survey provided at the link below. Your feedback will help us determine product usefulness, whether modifications are needed, and whether this will become a permanent addition to our warning format.

An online customer feedback survey is available at:

A service description document for this experiment is available on-line at:

A map showing affected offices is on-line at:

Additional questions or comments may be directed to: or

Return to News Archive is the U.S. government's official web portal to all federal, state and local government web resources and services.