Valuable severe weather dataset collected by students

The NSSL/CIMMS Severe Hazards Analysis and Verification Experiment (SHAVE) are collecting hail, wind damage and flash flooding reports through phone surveys from now through mid-August.  This is the sixth year of the project, logging more than 29,000 hail reports, 5500 wind reports and 9300 flash flood reports since the project began.

SHAVE reports, when combined with the voluntary reports collected by the NWS, creates a unique and comprehensive database of severe and non-severe weather events and enhances climatological information about severe storm threats in the U.S.  Some NWS forecast offices use SHAVE data to assist in verifying their warnings.

Largely student led and run, the SHAVE team makes phone calls along the path of a target storm.  People who answer the calls are questioned about hail size, wind damage and flash flooding that occurred over the past 60 minutes.  The phone data is blended with radar information on Google Maps to create a database on the storm for research.

NSSL/CIMMS researchers are using the SHAVE datasets as verification for multi-radar, multi-sensor detection algorithms and techniques, dual polarized radar, and a system that automatically detects supercell thunderstorms.

Because SHAVE leans heavily on students, it gives them rich opportunities for professional development and leadership.  It has also led to year-round undergraduate research assistantships and research projects for over half of the participants.  Between 2006-2011, 26 students have worked for SHAVE.

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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.

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