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For parts of the Central Plains, Pembina Valley and Red River Valley, it was one of the hottest days so far this year Tuesday, with temperatures soaring into the mid to upper 30s. The reason? A very hot and moist airmass from the southern U.S. was pushed into the region by a strong upper southerly flow.
"We have already had a number of days when temperatures have surpassed 30 degrees, and we are just past mid-June," noted CMOS Accredited Weathercaster Chris Sumner. "We typically see our hottest weather in July and August, but yesterday was yet another taste of that, but several weeks early."
The following data is courtesy of Environment Canada and the Manitoba Ag Weather Network:
Morris - 37.6
Kane - 37.4
Altona - 37.3
Carman - 37.0
Elm Creek - 36.8
Starbuck - 36.0
Winnipeg - 35.7 (record high)
Elie - 34.0
Portage - 31.4 (humidex was 40)
All temperatures in Celsius
Sumner noted, because of a nearly stationary frontal boundary draped over southcentral Manitoba, there were significant temperature differences only a relatively short distance between points.
"For example, Morden reach 37 degrees yesterday, but Clearwater, which is about 100 kilometers away, maxed out at 32," explained Sumner. "Five degrees is a pretty substantial difference in that relatively small geographical space. As you moved westward, and got further west of that boundary, temperatures dropped further, with highs 10 to 12 degrees cooler than the Red River Valley."
And what about all of those storms we were supposed to see Tuesday afternoon and evening?
"Areas right along that frontal boundary did see some thunderstorm development, and there were a handful of Severe Thunderstorm Warnings issued, but they were west of our region, which makes sense, because that front was the trigger to initiate those storms," said Sumner. "Because that front hardly moved yesterday, we were lacking a trigger in our region. On top of that, the atmosphere remained capped in our neck of the woods, meaning the air aloft was warmer than the air below, in atmospheric terms, and because of that storms could not develop."
According to Sumner, a slight severe thunderstorm risk returns to the area today, with that frontal boundary slowly marching eastward, providing that necessary trigger.
"Ample fuel remains in the atmosphere today, with warm, humid conditions in the mix for one more day," he added ."As we look ahead to Thursday and beyond, lingering instability from the slow progression of this frontal boundary may lead to showers Thursday morning and early afternoon, with temperatures coming back down to seasonal, around 22 to 24."
As for the weekend, Sumner is keeping an eye on the progression of an upper-level low moving northward out of the U.S. Rockies.
"This system will bring Southern Manitoba the best chance that we've had for quite a while for widespread shower and rainfall activity," he said. "Saturday and Sunday, at this point, seem the most likely days to see that, but there is still uncertainty regarding how this system will evolve and track, both impacting how much rain and where it may fall."
Along with that, temperatures are expected to be slightly below seasonal for the weekend, before turning warmer next week as upper level ridging returns to the region, and warmer air moves in.