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Friday, 5 February 2016

Assessing Past and Future Convective Storm Environments using the HAILCAST Model

(Jennifer Bruneau, Masters Student, University of Manitoba, Winnipeg, MB)

Severe convective weather poses a threat to society as it can lead to loss of life and has the potential to cause significant damage to property (including cars, buildings, and cropland) (Tippett et al., 2015). In a changing climate it is important to assess how the convective storm environment has changed in the past and how it may change in the future: as such, the two objectives of my research are to first look at how the convective storm environment has changed over a historical period and to assess the nature of changes to future convective environments. Both of these proposed objectives will be carried out using the HAILCAST model; HAILCAST will be run for a historical window (1971 to 2000) and a future window (2041 to 2070) using output from the NARCCAP regional climate model (RCM) simulations which are driven with the NCEP Reanalysis II data. The domain of this study is that of the Changing Cold Regions Network (CCRN) (western Canada, east of the continental divide), parts of eastern Canada, and all areas east of the Rocky Mountains in the United States.

This is the first time the HAILCAST model is being used to directly examine changes in historical and future convective storm environments instead of using proxy data to infer these changes. Proxy data are typically used because RCMs are considered to have spatial and temporal resolutions too coarse to accurately simulate convective storm environments (Kapsch et al., 2012). However, many authors that have explicitly examined past and/or future convective storm environments using high resolution RCMs have found their output to be reliable (Gensini, Ramseyer, & Mote, 2013; Mahoney et al., 2012; Sanderson et al., 2015). In particular, Fan, Bradley, and Rawlins (2015) acknowledge that fine-resolution RCMs are capable of resolving climate change over complex terrain, simulating extreme events, and representing mesoscale weather processes (such as convective storms). Further, the HAILCAST model is reliable in assessing where and when hailstorms and severe convective storms are likely to occur because it yields various useful severe storm parameters such as hail size, cloud top height, updraft duration, and profiles of updraft velocity.

Jennifer applied for CatIQ's Canadian Catastrophe Conference's Student Delegate Program.