ERA5-Based Significant Tornado Environments in Canada Between 1980 and 2020

This study uses ERA5 close-proximity soundings and associated convective parameters to characterize significant tornadic storm (F/EF2+) environments between 1980 and 2020 in parts of Canada. It is shown that ERA5 convective parameters are suitable to represent observed parameters, based on radiosonde comparisons. Results indicate that the eastern Canadian Prairies have nearly double the lifted condensation level with higher level of free convection compared to eastern Canada (southern Ontario/Quebec). Eastern Canada has more a humid boundary layer and free troposphere that can lead to warmer cold pools, favoring tornadogenesis. Central Canada (Manitoba) has the largest mixed-layer (ML) convective available potential energy (CAPE) mainly due to a combination of regional differences in low level moisture and steeper mid-level lapse rates in western Canada. Central continental U.S. and Canadian regions appear to have the highest (most negative) convective inhibition, leading to more explosive initiation. Mean bulk wind shear and storm relative helicity (SRH) increases from west to east, with eastern regions being significantly larger. The supercell composite and significant tornado parameters are generally less than U.S. magnitudes, particularly in western Canada, and would require recalibration for more practical use in Canada. Overall, western Canada significant tornadic storms are associated with more low-level looping hodographs and dominated by thermodynamic influences compared to larger wind influences in eastern regions. This is likely due to more spring, late summer, and autumn events that typically have well-developed synoptic systems (stronger wind shear) with overall less buoyant energy in eastern regions. This study identifies the meteorological conditions associated with strong tornadoes in parts of Canada with brief comparisons to other regions of the World. The main findings suggest that western Canada (Prairies) events are more dominated by the thermodynamic environment compared to eastern Canada that has more wind shear. Western regions tend to have more wind direction changes in the lower atmosphere compared to eastern regions. These differences may partially be due to eastern regions having more events in spring and autumn, where large scale weather systems tend to be more developed but with less thermal instability. All of these results suggest that strong tornadoes can occur in various environments within Canada, particularly similar to the U.S., however, some commonly used tornado forecasting indices may require recalibration to suit western Canadian environments. Strong tornado environments in western Canada are more influenced by thermodynamics versus stronger wind shear in eastern Canada SCP and STP parameters require recalibration for western Canada, likely through wind shear term adjustments The six Canadian regions identified have statistically different strong tornado environments, given the convective parameters used