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Abstract A localized tornado and severe hail climatology is updated and enhanced for eastern Colorado. This region is one of the most active severe weather areas in the United States because of its location immediately east of the Rocky Mountains, intrusions of Gulf of Mexico moisture into a dry climate, and various small-scale topographically forced features such as the “Denver Cyclone.” Since the 1950s, both annual tornado and severe (≥1.0 in.; 1 in. = 25.4 mm) hail reports and days have been increasing across the area, but several nonmeteorological factors distort the record. Of note is a large population bias in the severe hail data, with reports aligned along major roadways and in cities, and several field projects contributing to an absence of (E)F0 tornado reports [on the (enhanced) Fujita scale] in the 1980s. In the more consistently observed period since 1997, tornado reports and days show a slight decreasing trend while severe hail reports and days show an increasing trend, although large variability exists on the county level. Eastern Colorado tornadoes are predominantly weak, rarely above (E)F1 intensity, and with a maximum just east of the northern urban corridor. Severe hail has a maximum along the foothills and shows a trend toward a larger ratio of significant (≥2.0 in.; ≥50.8 mm) hail to severe hail reports over time. Both tornadoes and severe hail have trended toward shorter seasons since 1997, mostly attributable to an earlier end to the season. By assessing current and historical trends from a more localized perspective, small-scale climatological features and local societal impacts are exposed—features that national climatologies can miss. 

Abstract Eastern Colorado is one of the most active hail regions in the United States, and individual hailstorms routinely surpass millions of dollars in crop loss and physical damage. Fifteen semistructured interviews with eastern Colorado farmers and ranchers were conducted in the summer of 2019 to gauge perceptions of the severity and vulnerability associated with hailstorms, as well as to understand how forecasts and warnings for severe hail are received and acted upon by the agricultural community. Results reveal a correspondence between perceived and observed frequency of hailstorms in eastern Colorado and highlight financial losses from crop destruction as the greatest threat from hailstorms. In contrast to the National Weather Service defining severe hail as at least 1.0 in. (25.4 mm) in diameter, the agricultural community conceptualizes hail severity according to impacts and damage. Small hail in large volumes or driven by a strong wind are the most worrisome scenarios for farmers, because small hail can most easily strip crop heads and stalks. Larger hailstones are perceived to pose less of a threat to crops but can produce significant damage to physical equipment and injure livestock. Eastern Colorado farmers and ranchers are avid weather watchers and associate environmental cues with hailstorms in addition to receiving warning messages, primarily via alerts on mobile telephones. Hailstorms elicit feelings of dejection and anxiety in some respondents, whereas others accept hailstorms as part of the job. Increasing awareness of the agricultural perceptions of hailstorms can help the meteorological community direct hail prediction research efforts and improve risk communication to the agricultural sector. 

Abstract Severe convective storms along the Front Range and eastern plains of Colorado frequently produce tornadoes and hail, leading to substantial damage and crop losses annually. Determination of future human exposure from these events must consider both changes in meteorological conditions and population dynamics. Projections of EF0 + tornadoes (on the enhanced Fujita scale) and severe [1.0+ in. (25.4+ mm)] hail reports out to the year 2100 are computed using convective parameter proxies generated from dynamically downscaled GFDL Climate Model, version 3 (GFDL CM3), output by the WRF Model for control and future climate scenarios. The proxies suggest that tornado and hail days in the region may increase by up to one tornado day and three hail days per year by 2100, with the greatest increases across northeastern Colorado. Using a spatially explicit Monte Carlo model, projected future frequency and spatial changes in tornadoes and hail are superimposed with population projections from the shared socioeconomic pathways (SSPs) to provide a range of possible scenarios for end-of-century human exposure to tornadoes and hailstorms. Changes in hazard frequency and spatial distribution may amplify human exposure up to 117% for tornadoes and 178% for hail in the region by 2100, although specific results are sensitive to uncertain combinations of future overlaps between hazard spatial distribution and population. Findings presented herein not only will provide the public, insurers, policy makers, land-use planners, and researchers with estimates of potential future tornado and hail impacts in the Front Range region, they also will allow the weather enterprise to better understand, prepare for, and communicate tornado and hail risk to eastern Colorado communities.