MANITOBA: Thunderstorm Forecast for Tuesday, June 20, 2023
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FORECAST DISCUSSION
Southern Manitoba is set to experience what will likely be the most expansive and strongest severe weather risk of the season thus far on Tuesday evening. Storm development is expected to initiate around the Brandon and Portage La Prairie region during the evening hours, with further development anticipated to the northeast throughout the Interlake region.
Based on the projected atmospheric conditions, it is highly likely that these storms will rapidly intensify and reach severe levels, carrying the potential to generate hail as large as baseballs, wind gusts up to 115 km/h, and possibly even a tornado.
Some uncertainty remains regarding the exact timing, as models indicate later evening development. However, the environment is most favourable earlier in the day, benefitting from daylight heating, which would further enhance the storm intensity.
We contemplated introducing a 'significant' risk zone in South-central Manitoba primarily for the hail threat. However, due to timing considerations, we opted to maintain a strong risk level. Instead, we have designated a hatched region on the map to highlight the areas with the greatest potential for significant hail.
Severe activity is expected to persist into the overnight hours, similar to Monday night. During this time, the Winnipeg region and areas to the east could encounter some severe weather. However, it appears that the overall threat, including the tornado risk, will decrease significantly, transitioning more toward a damaging wind risk.
TORNADO RISK
Regarding the tornado risk, a widespread risk of one or two tornadoes extends from Brandon through Portage La Prairie and into Pegus. Although we contemplated introducing a 'several' risk zone, our confidence is not sufficient, so we chose to indicate the strongest tornado risk with a hatched region in South-central Manitoba. While we are fairly confident that at least one tornado will occur within the hatched region, it is not guaranteed.
Surrounding regions, including Virden, Russell, Dauphin, and Winnipeg, have an isolated tornado risk. However, the likelihood is questionable at best, considering the late timing when the storms are expected to impact these areas.
