U.S. Hail Frequency and the Global Wind Oscillation

Vittorio A. Gensini, John T. Allen

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Changes in Earth relative atmospheric angular momentum can be described by an index known as the Global Wind Oscillation. This global index accounts for changes in Earth's atmospheric budget of relative angular momentum through interactions of tropical convection anomalies, extratropical dynamics, and engagement of surface torques (e.g., friction and mountain). It is shown herein that U.S. hail events are more (less) likely to occur in low (high) atmospheric angular momentum base states when excluding weak Global Wind Oscillation days, with the strongest relationships found in the boreal spring and fall. Severe, significant severe, and giant hail events are more likely to occur during Global Wind Oscillation phases 8, 1, 2, and 3 during the peak of U.S. severe weather season. Lower frequencies of hail events are generally found in Global Wind Oscillation phases 4–7 but vary based on Global Wind Oscillation amplitude and month. In addition, probabilistic anomalies of atmospheric ingredients supportive of hail producing supercell thunderstorms closely mimic locations of reported hail frequency, helping to corroborate report results.

Original languageEnglish
Pages (from-to)1611-1620
Number of pages10
JournalGeophysical Research Letters
Issue number3
StatePublished - Feb 16 2018


  • GWO
  • climate
  • convection
  • extremes
  • hail
  • thunderstorms


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