NWC REU 2018
May 21 - July 31



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Seasonal Evaluation of Storm Life Cycles in the CONUS from 12 Years of Radar-Based Storm Tracks

Aodhan Sweeney


What is already known:

  • Forecasters in a given region may be familiar with characteristics of storms local to them (for example summer storms in Florida) but not in a location on far away from where they work.
  • Previous knowledge on storm properties typically comes from case studies of specific storms as opposed to a statistical analysis of all storms in a given time period.
  • Storms are potentially dangerous events, and it is in our best interest to know more about their general trends to help mitigate their risk.

What this study adds:

  • A large-scale statistical study that describes storm characteristics (mean direction, speed, spatial expanse, lifetime) over the continental United States within a 12 year period from January 2000 - December 2011, allowing for less reliance on anecdotal or case study experience.
  • An equal area map of the continental United States showing relative storm frequency, with a filtering to show frequency for different seasons.
  • This study corroborates many previously expected results for storm properties (such as a higher frequency of storms in summer than winter).


While there is considerable knowledge of the global distribution of precipitation, lightning, and severe weather, little is known about the statistics of storm life cycles responsible for these phenomena. Previous studies have used long-term and large-scale data related to severe storms, but never for a survey on the trends of these storms over the CONUS. An objective, long-term study that looks into basic characteristics such as duration, path, speed, or the geographic/diurnal/seasonal variability of storms would shed light on their fundamental trends over the CONUS. A question that may arise is ”why has this type of survey not yet been done?”. This is due to two reasons: 1) lack of a suitable storm tracking algorithm capable of identifying and stitching storms for this type of project, and 2) no single dataset with complete radar composites over a sufficiently long period. With a specific tracking algorithm generated for this project and the availability of storm track data in the MYRORSS (Multi-Year Reanalysis of Remotely Sensed Storms) database, a primary survey was conducted. Storm activity was found to reach its maximum over the Southeastern United States and showed signatures of orographic forcing in the west. Statistical trends showed consistency across seasons in average lifetime and direction of storms, but variation among average speed and spatial expanse.

Full Paper [PDF]