The summer has moved in, but the hot temperatures have moved out!
If you have been following my forecasts and weather articles, you know that it only takes one system to change the overall flow over the atmosphere. That leads to a new weather pattern across a region. We saw this last week when a northern Alberta low moved into Saskatchewan and then intensified as it dropped southeastwards across southern Manitoba.
While the low was not particularly wet, some areas saw upwards of 50 mm or precipitation. But it was the size of the low the impacted the general weather pattern. At one point, the low covered most of Manitoba and about half of Saskatchewan. Something that large ultimately changes the weather pattern.
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Prairie forecast: Potential to turn cool and wet
For this forecast period we are starting off with a large area of high pressure over Ontario and an equally large area of low pressure over the Yukon. The clockwise flow around the Ontario high, combined with the counterclockwise flow around the Yukon low, is creating a widespread southerly flow across the Prairies. This should lead to one more day of warm temperatures across the western Prairies and a couple more days over the eastern half.
When trying to figure out how best to describe this forecast period, the word that stood out for me was ‘muddled.’ There are no forecasted strong areas of low pressure—but on the other hand, there are several areas of low pressure that could become strong. So another tough forecast.
Looking at the big picture we start this forecast period with a generally zonal flow across the Prairies as Arctic high pressure slides across the far northern Prairies and weak low pressure moves by to the south. This will bring sunny to partly cloudy skies and near to slightly below-average temperatures.
By the weekend, a weak area of low pressure is forecasted to move into Alberta and then slowly propagate across the Prairies. This should bring widely scattered showers and thundershowers and near-average temperatures. This pattern of unsettled conditions and near-average temperatures looks to continue right through to the end of the month.
Alberta
We start this forecast period with weak instability over far northern and southern regions as two areas of low pressure slide by with weak high pressure in between. Far southern regions will see a mix of sun and clouds and a few showers or thundershowers. Central regions will see more sun than clouds. Daytime highs will be in the low twenties across most regions.
As the area of high pressure over central regions drifts eastwards, energy from the southern low is forecasted to lift northwards. This should bring partly cloudy skies and the chance of showers and thundershowers to most regions on Friday and Saturday. By Sunday, most of the instability should have moved eastwards to bring some drier conditions as weak high pressure builds back in. With increased sunshine expected, daytime highs should warm back into the mid-twenties to start the week.
Saskatchewan and Manitoba
Arctic high pressure sliding through the far northern parts of both provinces should bring sunny to partly cloudy skies right through to the weekend. Daytime highs should be seasonable with most regions falling to the 20 to 25 C range, depending on cloud cover and smoke. With Arctic high pressure feeding cool air into the region, expect overnight lows to be in the 7 to 11 C range with more northern regions dropping into the 3 to 6 C range.
It looks like there will be an uptick in temperatures over the weekend and the first part of next week as a weak area of low pressure moves eastwards. Along with the warmer temperatures, expect partly cloudy skies and the chance of afternoon showers and thundershowers.
The main energy from the weak low looks to move off into Ontario by Monday, which will allow weak upper-level ridging to build over the eastern Prairies. Should this materialize, expect plenty of sunshine and temperatures warming into the upper twenties by Tuesday or Wednesday.
