The Frequency of High-Impact Convective Weather Events in the Twin Cities Metropolitan Area, Minnesota

Abstract

Thunderstorms frequently produce brief flooding or minor damage, though far fewer lead to major flooding and widespread or significant damage. Outbreaks of such storms exact large tolls on their victims and can compromise, or completely overwhelm, the emergency response infrastructure. This paper derives empirical frequencies and recurrence intervals of ''high end'' convective weather events in the Minneapolis-St. Paul, Minnesota, metropolitan area from archived tornado, hail, damaging-wind, and high-density daily rainfall data, as well as historical records and accounts. Two classes of high-impact events are analyzed: those with the potential to produce widespread damage or disruption and those virtually certain to do so. Storms in this first class recur within the area, on average, 3 times per year, while the more extreme storms recur every 2-2.5 yr on average. Owing to well-established spatial and temporal inhomogeneities in observed severe weather data, true recurrence intervals are probably somewhat shorter. In the context of ongoing regional population growth, the area is becoming increasingly vulnerable to major damage and potential casualties from these major storm events.

The effect of urbanisation on the climatology of thunderstorm initiation

“…Although many urban precipitation studies have used rain‐gauge data (Blumenfeld, ; Hand and Shepherd, ), remotely sensed, quality‐controlled products may be a better tool to characterize the short‐ to long‐term effects of developed areas on regional hydroclimatology (Dixon and Mote, ; Ashley et al , ; Bentley et al , ). Recent studies on urban rainfall anomalies have used satellite precipitation estimates (Rosenfeld, ; Shepherd et al , ; Hand and Shepherd, ), lightning data (Bentley and Stallins, ; Stallins et al , ; Altaratz et al , ; Gauthier et al , ; Lang and Rutledge, ; Coquillat et al , ), and ground‐based radar data (Dixon and Mote, ; Mote et al , ; Ashley et al , ; Bentley et al , ; Ganeshan et al , ).…”