NWC REU 2011
May 23 - July 29



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Investigation of Radar Variables and Near Surface Environments for Developing a Surface Hail Fall Product

Sarah Mustered, Kiel Ortega


What is already known:

  • Surface hail fall poses a significant threat to life and property, but the processes that affect hail size and spatial distribution are not well understood.
  • Current hail products focus on hail detection aloft.
  • A gridded surface hail product is needed to better track severe hail events.

What this study adds:

  • The addition of NSE data to radar variables did not stratify hail size categories.
  • Use of high spatial resolution verification data will require more novel searching and matching techniques.
  • While addition of NSE data did not stratify the hail sizes, it did highlight certain parameter spaces which are more (or less) conductive to large hail production.


In 2006, the Severe Hazards Analysis and Verification Experiment (SHAVE) was formed to collect high resolution severe weather reports. The resulting dataset is a detailed and accurate record of surface hail fall. Currently, the exact processes that determine the size and distribution of hail at the surface is relatively unknown. While there are numerous products that address the presence of hail cores aloft, a gridded surface product is missing. The benefit of a gridded surface product is a more accurate understanding of surface hail size at any particular location. In this study, we incorporated the near surface environment (NSE) from the 20 km RUC analysis and existing radar products with SHAVE hail reports to determine if the NSE could be a beneficial component of a surface hail fall product. We found that the current resolution and reliability of the NSE data is too low for the addition of NSE variables to add significantly to the accuracy of the existing radar products.

Full Paper [PDF]