Last week’s forecast got off to a rough start. The area of low pressure that pushed through the eastern Prairies ended up as a large upper level low. Because those are slow to move out, they can affect systems trying to move east by backing them up or forcing them to take a different path. So, while the overall pressure pattern across the Prairies was still slack as forecasted, the details got all messed up.
Also of interest, even though the overall pattern wasn’t that warm, we still saw some hot temperatures.
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Looking at this forecast period, and as we near the end of meteorological summer, it’s still looking like summery temperatures will stick around. Along with those warm temperatures we will continue to see the chance of thundershowers and storms.
We start with a weak trough of low pressure over the eastern Prairies that is slowly pushing an upper ridge eastward out of the region. This trough has been the focus of scattered thunderstorms and looks to continue this over the next couple of days. Over the western Prairies we are starting with high pressure building in from the west. This may trigger a few thunderstorms as it pushes in before bringing several days of quiet weather.
Over the weekend the weather models are showing an area of low pressure developing over Montana, tracking due north through Alberta and then either stalling out over the Northwest Territories on Monday or tracking eastwards. There’s uncertainty the behaviour of this low, which could have a significant impact on the weather near the end of this forecast period.
This system will bring a good chance of clouds, showers, thunderstorms, and cooler temperatures to parts of Alberta and northern Saskatchewan. Over the eastern Prairies, the southerly flow ahead of this low will bring warm temperatures with a small chance of thunderstorms late in the weekend as a warm front from the low lifts northwards. Quieter and more seasonable temperatures look to be on tap for the first half of next week as the flow across the Prairies becomes more westerly.
Alberta
High pressure is forecasted to build in from the northwest over the next couple of days. Ahead of this high the weather models are showing a weak trough of low pressure being pushed southwards. This system will bring the chance of showers and thunderstorms with the best chance being over central and western regions. Temperatures will be a little cooler on Wednesday before warming up on Thursday and Friday under plenty of sunshine. Expect daytime highs to be in the low twenties on Wednesday, warming into the upper twenties to around thirty degrees by Friday.
Over the weekend, an area of low pressure is forecasted to develop over Montana and lift northwards. It looks like most precipitation accompanying this low will be over western and northern regions on Saturday and Sunday. There is the possibility of a secondary area of low pressure spinning up over north-central Saskatchewan on Sunday. Should this happen, eastern regions could see some measurable precipitation on Monday.
The weather models are not sure what will happen with this low as they have been showing it both stalling out over Great Slave Lake and being more progressive and sliding off to the east. Should it stall, the flow around the low will push cool unstable air into the north half of the province. Most days would a mix of sun and clouds with the chance of afternoon showers and thundershowers. Daytime highs will be in the upper teens with overnight lows dropping to around 8 C. If it doesn’t stall, temperatures will be milder with less chance of clouds and showers. Further south, skies should be sunny to partly cloudy with daytime highs in the low twenties and overnight lows in the 10 C range.
Saskatchewan and Manitoba
This region will continue to see scattered thunderstorms over the next couple of days as weak areas of low pressure ride up the western side of the departing upper ridge. The main focus looks to be over eastern Saskatchewan and western Manitoba on Wednesday with the weather models showing the possibility of some severe storms. This activity will push into southern and central Manitoba on Thursday and bring with plenty of clouds and a good chance of showers and occasional thundershowers. With the clouds and precipitation, expect daytime highs to only be in the low twenties.
By Friday Saskatchewan will have cleared out with Manitoba clearing out during the day. Over the weekend a fairly strong southerly flow will develop ahead of the Alberta low. This will bring sunny, hot, and windy conditions with daytime highs pushing thirty degrees and overnight lows only falling into the mid teens. The weather models are hinting at a secondary area of low pressure developing over north-central Saskatchewan on Sunday. Should this materialize, there will be the chance of late thundershowers or storms over central Saskatchewan and over much of southern and central Manitoba.
On Monday the flow across the Prairies is forecasted to become westerly. This will bring sunny to partly cloudy skies along with seasonable temperatures. Expect daytime highs to be in the low to possibly mid twenties with overnight lows falling to around 10 C.
— Daniel Bezte is a teacher by profession with a B.A. (Hon.) in geography, specializing in climatology from the University of Winnipeg. He operates a computerized weather station near Birds Hill Park, Man. Contact him via email with your questions and comments.Â
