On the episodic nature of derecho-producing convective systems in the United States

Abstract

Convectively generated windstorms occur over broad temporal and spatial scales; however, one of the larger-scale and most intense of these windstorms has been given the name 'derecho'. This study illustrates the tendency for derechoproducing mesoscale convective systems to group together across the United States -forming a derecho series. The derecho series is recognized as any succession of derechos that develop within a similar synoptic environment with no more than 72 h separating individual events. A derecho dataset for the period 1994-2003 was assembled to investigate the groupings of these extremely damaging convective wind events. Results indicate that over 62% of the derechos in the dataset were members of a derecho series. On average, nearly six series affected the United States annually. Most derecho series consisted of two or three events; though, 14 series during the period of record contained four or more events. Two separate series involved nine derechos within a period of nine days. Analyses reveal that derecho series largely frequent regions of the Midwest, Ohio Valley, and the south-central Great Plains during May, June, and July. Results suggest that once a derecho occurred during May, June, or July, there was a 58% chance that this event was the first of a series of two or more, and about a 46% chance that this was the first of a derecho series consisting of three or more events. The derecho series climatology reveals that forecasters in regions frequented by derechos should be prepared for the probable regeneration of a derecho-producing convective system after an initial event occurs.

Corridors of Warm Season Precipitation in the Central United States

“…In a 15-yr climatological study of derechos (large-scale convectively induced wind storms), Bentley and Sparks (2003) showed that more than half occurred in groups lasting several days. Ashley et al (2005) found similar results when using a larger derecho dataset and more conservative criteria for delineating derecho groupings. Approximately 62% of derechos were members of a series, with most series involving two or three derecho events (ϳ24% of series contained four or more events).…”

Reconstruction of a meteotsunami in Lake Erie on 27 May 2012: Roles of atmospheric conditions on hydrodynamic response in enclosed basins

“…As a result, very few meteotsunami events have been reported in the Great Lakes to date. Thus, the use of remote sensing observations such as radar radial velocity as well as next‐generation atmospheric and hydrodynamic modeling systems are crucial to improve our ability to understand the mechanisms that cause meteotsunamis and how their frequency and intensity might change with increasingly frequent strong convective events [ Bentley and Sparks , ; Ashley et al ., ]. As enclosed basins, the Great Lakes may pose a unique set of conditions with regard to meteotsunamis, and the ability to detect these extreme storms and predict the hydrodynamic response is crucial to reducing risk and building resilient coastal communities.…”

Climate extremes in the United States: recent research by physical geographers

“…affirmed the patterns proposed by these earlier studies in their analysis of derechos. Another interesting finding is the tendency for derechos to group together in families in time and space (Ashley, Mote, & Bentley, 2005;Bentley & Sparks, 2003).…”