TJ23.2 Do hailstorms and tornadoes really 'rest on weekends'?

Tuesday, 8 January 2013: 2:00 PM
Room 5ABC (Austin Convention Center)
Sandra Yuter, North Carolina State Univ., Raleigh, NC; and M. A. Miller, M. D. Parker, P. M. Markowski, Y. P. Richardson, H. E. Brooks, and J. M. Straka

It has been argued that there is an unnatural propensity for hailstorms and tornadoes to 'rest on weekends' in a statistically notable way. This is attributed to claims that there are fewer aerosols in the atmosphere on weekends than week days. Based on solid statistical, meteorological, and observational grounds, rather, it is shown that 1) this minimum is absent when different time periods are used or when "tornado days" are considered rather than counts of individual tornadoes, 2) a lack of integrating concepts about storm dynamics and associated microphysics has led to overly generalized arguments, and 3) aerosol averaging over broad geographical regions is inappropriate for assessing their influence on tornadoes. We find that hailstorms and tornadoes do not, in fact, rest on weekends, and we present a number of physical arguments for why a weekly cycle would not be expected anyway.
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