In almost a carbon copy repeat of what happened Saturday afternoon and evening, another round of pop-up thunderstorms rumbled over parts of the Pembina and Red River Valleys Sunday afternoon and evening.

"A trough of low pressure sweeping through Southern Manitoba, along with a cold front, helped kick start those storms alongside daytime heating which led to convection developing," explained CMOS Accredited Weathercaster Chris Sumner. "The storms were scattered in nature, but once again, those places that did have one go overhead saw brief, heavy downpours. Altona received 10mm in less than 30 minutes Sunday night."

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The following totals are for Sunday, July 7th and are courtesy PembinaValleyOnline Rainwatchers, Environment Canada and the Manitoba Ag Weather Network.

South of Morden - 33mm (Sat 30mm, 3mm Sunday)
Altona - 10mm (4/10th)
Snowflake - 4.8mm
Gretna - 2.6mm (about 1/10th)
Emerson - 1.1mm
Windygates - 0.9mm
Rosenfeld - trace
25mm = 1 inch

"Monday will be warm and humid, with yet another chance of late afternoon and evening thunderstorms, very much like what we saw across much of Southern Manitoba Saturday and Sunday," noted Sumner. "Daytime heating could lead to another round of pop-up thunderstorms, but we’re not expecting any severe storms today, but like the weekend, whatever daytime convection does develop, it could lead to brief downpours. We may see a similar scenario play out tomorrow, as well." 

Temperatures Monday and Tuesday will range between 27 and 29 degrees, but feel like the low to mid 30s with the humidity factored in. Hazy skies will also be part of the mix, according to Sumner, with the northwesterly flow aloft tied to the upper level low which has been impacting our region for a while, pushing some smoke into our area, but the expectation is it will stay elevated in the atmosphere, hence the hazy sky today and tomorrow.

"As we look beyond Tuesday, atmospheric ridging settles in, accompanied by surface high pressure, and the stage is set for an extended period of hot and humid conditions," he said. "Southerly winds at the surface, alongside moisture being pulled up from the Gulf of Mexico will have it feeling like the kind of Southern Manitoba Summer we are used to. Wednesday through the weekend, the forecast models are indicating lots of sunshine, hot temperatures and muggy conditions. There’s little chance of widespread precipitation Wednesday through Friday, with highs between 29 and 32, but feeling like the mid to upper 30s most days with the humidity factored in."

He noted we could see a pop-up thunderstorm over that stretch, considering how much moisture is around, and the amount of daytime heating we will be getting. 

"Preventing that from happening will be warm air aloft, or an atmospheric cap, which will inhibit that thunderstorm development, but again could one here or there pop-up in true Summer fashion, for sure."

Averages for this point in July are 26 degrees daytime and 13 degrees overnight.