CIMMS Researchers Work with Public to Document Hail Size Occurrence

Researchers at the Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) at the University of Oklahoma and NOAA’s National Severe Storms Laboratory (NSSL) are working with the public to document hail size occurrence during severe weather events in central Oklahoma this spring. The Hail Size Discrimination Experiment (HaSDEx) calls upon volunteers of any age and education level (including teachers, families, and classes) to safely observe and report hail size when hail occurs in their areas. A project website (http://www.nssl.noaa.gov/projects/hail07) has been established to input hail observations and to review hail safety and education. Volunteers can spend as little (or as much) time as they wish in making observations. The basic idea is simple: CIMMS and NSSL scientists collect radar data during severe weather events, but they need to know what is happening on the ground. Has hail occurred? If so, what was the maximum size observed? Hail size data are particularly rare, and scientists need as many hail-size observations of them as possible. Storm chasers and emergency personnel also are encouraged to record where and when they encounter hail.

Background: Hail is a form of precipitation that occurs when updrafts in thunderstorms carry raindrops upward into extremely cold areas of the atmosphere, where they freeze into ice. Severe thunderstorms can produce destructive large hail. Nationwide, hail causes nearly $1 billion in damage to property and crops each year.

Significance: This project supports CIMMS and NSSL scientists involved in developing new radar technologies and techniques to determine not only the presence of hail, but the size of the hail falling at any given location. Volunteers provide valuable information that will allow scientists to compare what has been observed on the ground with what the radar has detected. This research supports NOAA’s Mission Goal 3 – Serve Society’s Needs for Weather and Water Information.