A Climatology of Extratropical Cyclones Leading to Extreme Weather Events over Central and Eastern North America

1. Introduction

Extratropical cyclones (ECs) play a major role in determining day-to-day weather conditions in the middle latitudes during the cool season. Particularly strong ECs, such as the infamous Superstorm of March 1993 (SS93) (e.g., Huo et al. 1995; Kocin et al. 1995; Uccellini et al. 1995; Alfonso and Naranjo 1996; Bosart et al. 1996; Dickinson et al. 1997; SPC 1999), can have considerable socioeconomic impacts on the regions they traverse due to their frequent association with damaging winds and heavy precipitation (e.g., Salmon and Smith 1980; Gyakum 1983a,b; Uccellini et al. 1984, 1985; Hakim et al. 1995, 1996; Mailier et al. 2006; Dacre et al. 2012). Particularly strong ECs forming over and traversing densely populated regions of central and eastern North America have the potential to lead to extreme weather events (EWEs), defined in the present study as high-impact weather events that are societally disruptive, geographically widespread, exceptionally prolonged, and climatologically infrequent. Figure 1 illustrates the mean sea level pressure (MSLP), 925-hPa winds, and 925-hPa standardized wind speed anomalies associated with SS93 at 0000 UTC 14 March 1993. The areal extent and magnitude of 925-hPa standardized wind speed anomalies associated with SS93 in Fig. 1 are characteristic of the 925-hPa standardized wind speed anomalies associated with SS93 throughout the majority of its 84-h life cycle (1200 UTC 12 March-0000 UTC 16 March 1993), suggesting that SS93 meets the definition of an EC leading to an EWE. This suggestion is supported by the first-place ranking of SS93 on the Northeast Snowfall Impact Scale (Kocin and Uccellini 2004), which classifies SS93 as the highest-impact Northeast U.S. EC since 1950 (NCEI 2018).

ECs forming over and traversing central and eastern North America were extensively documented during the twentieth and early twenty-first centuries (Table 1). Early climatologies of North American ECs were painstakingly created using paper maps and hand analyses (e.g., Saucier 1949; Hurley 1954; Petterssen 1956; Klein 1957). The advent of reanalysis datasets during the late twentieth century allowed the meteorological community to construct comprehensive, long-term...