First severe thunderstorm threat of the season ahead for Saskatchewan


Summer is approaching rapidly and as the warm temperatures settle over the Prairie Provinces, it brings with it the threat of severe weather. According to ECCC, the main threats will be large hail, torrential downpours and damaging winds. This severe weather setup does not seem very good for intense supercells and should mostly favour multicell storm modes. Therefore, tornadoes are not expected out of this system.

Simulated reflectivity (radar) for the next two days

Above animation shows several rounds of storms firing in Montana and moving north across southern Saskatchewan on Tuesday and Wednesday. A ridge (see below) will be bringing warm-moist air from the Gulf of Mexico to parts of Saskatchewan and Manitoba. This moist airmass, combined with significant upper-level forcing, will bring a threat for severe thunderstorms to parts of Saskatchewan tomorrow into Wednesday night.

NAM 12km 500mb geopotential heights


The trough will not be moving very fast downstream (to the east) and therefore several rounds of severe thunderstorms may be possible over the next 48hrs in the same area. For these reasons, SLIGHT risks for severe thunderstorms have been issued by the Storm Prediction Center for Tuesday and Wednesday, which extends into southern Saskatchewan:


Tuesday May 19, 2020

Day 2 convective outlook issued by the US Storm Prediction Center

Wednesday May 20, 2020

Day 3 convective outlook issued by the US Storm Prediction Center

From the Prairie and Arctic Storm Prediction Centre (Canada):


"LOOKS LIKE A GOOD CHANCE FOR A ROUND OF ELEVATED CONVECTION MONDAY NIGHT MOVING OUT OF MONTANA INTO SOUTHERN ALBERTA AND SOUTHWESTERN SASKATCHEWAN WITH THE POTENTIAL FOR ISOLATED STRONG TO SEVERE THUNDERSTORMS. THAT ACTIVITY WILL WEAKEN AND PUSH OFF TO THE NORTHEAST ON TUESDAY, THEN ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS IS POSSIBLE AGAIN OVER THE SOUTHWESTERN CORNER OF SASKATCHEWAN ON TUESDAY NIGHT. AGAIN, ISOLATED STRONG TO SEVERE THUNDERSTORMS MAY BE POSSIBLE. A MARGINAL RISK OF THUNDERSTORMS EXISTS ON TUESDAY AFTERNOON OVER THE SOUTHWESTERN CORNER OF THE PROVINCE, HOWEVER RISK IS VERY MARGINAL AND DEPENDENT ON ENOUGH HEATING AND MOISTURE POOLING, WHICH IS FAR FROM A GUARANTEE AT THIS TIME OF YEAR. "