Standardizing the Definition of a "Pulse" Thunderstorm
Miller, Paul W. ; Mote, Thomas L.
Isolated, short-lived thunderstorms forming in weakly forced environments are referenced through a surplus of terminology. Further, the language used to describe the strongest, severe-weather-producing subset of these storms is applied inconsistently, posing a communication hurdle for the effective dissemination of hazardous weather risks. The term "pulse thunderstorm" was originally coined to describe an anomalously strong airmass thunderstorm often associated with a larger convective complex. However, recent applications of ?pulse? have evolved to also describe nonsevere, single-cell storms, and both uses can currently be observed within research, operational, and educational texts. This paper reviews the history of the term ?pulse,? performs a content analysis on nearly 1,500 pulse-referencing Storm Prediction Center (SPC) convective outlooks (CO) and mesoscale discussions (MD), and summarizes the deficiencies with the contemporary disorganized convection nomenclature. The larger CO sample (n = 997) establishes that temporal trends in ?pulse? references model traditional expectations whereas the detailed MDs (n = 458) showcase examples of pulse-related terminology. The MD content analysis reveals that 1) the term ?pulse? frequently appears in conjunction with severe-weather-related language and 2) that pulse-related words (e.g., brief, isolated) are equally represented in multicell-referencing MDs. In the interest of effective communication and reproducible research, the definition of ?pulse? is proposed to be standardized according to the term's original (i.e., severe, multicellular) meaning. Further, thunderstorms forming within synoptically homogeneous air masses in the absence of large-scale dynamical lift are suggested to be termed ?weakly forced thunderstorms.? By corollary, pulse storms represent the subset of weakly forced thunderstorms associated with severe weather.
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