Public hail observation program ready for spring

NSSL’s HaSDEx program is live and ready for spring severe weather.  Volunteers within 90 miles of Norman, Oklahoma are invited to document date, time, location and the size of hail through a link online at:

NSSL researchers will merge the reported observations with data from the dual-polarized KOUN radar to investigate the relationship of polarimetric variables to hail size.  The information will be used to refine hail detection algorithms designed to diagnose storm characteristics and intensity and improve warnings for hail producing storms.

HaSDEx volunteers are anonymous and make no long-term commitments.  In the past two years NSSL has logged thousands of reports.

Background: Dual-polarized radars transmit radio wave pulses with both horizontal and vertical orientations to more accurately measure cloud particles and precipitation size, shape and density. This additional information results in improved estimates of rain and snow rates, better detection of large hail location in summer storms, and improved identification of rain/snow transition regions in winter storms. The WSR-88D radars in the NEXRAD network will be upgraded with polarimetric technology beginning in 2010, extending their functionality and effectiveness.

Significance: Enhances public awareness of atmospheric science and severe weather hazards and severe weather safety.