Originally published on May 15, 2024 on Manitoba Co-operator
By Daniel Bezte
In the last forecast, I stated that it looked like summer like temperatures would move in towards the May long weekend, but there was plenty of time for change. Well, guess what? Things have changed.
Last week’s forecast played out close to what the weather models were predicting, with a couple of exceptions. First, the intensity of the systems was a little stronger than predicted. Second, some annoying upper lows ended up getting trapped or caught up with these systems. If you have followed my weather articles over the years, then you know just what upper lows can do to the weather and weather forecasts.
For this forecast period, well, it’s a bit of a mess. Overall, it looks like we could be stuck in a cool, wet pattern until the end of the month. The weather models show a broad area of upper low pressure developing across much of western and northern Canada over the next week or two. Within this area, there will be several areas of surface low pressure moving across our region. The interplay between the surface lows and the stronger areas of upper low pressure will slow down and intensify the surface lows at times.
The main problem will be exactly when and where these interactions will take place. This means certainty in the overall picture is pretty high, but there’s a fair bit of uncertainty in the finer details, especially later in the forecast. Using the latest model guidance here is the big picture.
An area of low pressure is forecasted to develop over B.C. and move east through Alberta on Thursday. It will slowly intensify as it tracks across Saskatchewan and into Manitoba late Friday. That low is then forecasted to track northwards as it follows the counterclockwise flow around the large upper low.
A second low is forecast to develop over Montana on Sunday and track northeas into Manitoba by Monday as it to tracks northwards in the same upper low. The same counterclockwise rotation will be pulling cool air southwards which will impact temperatures. Daytime highs are forecasted to be a good 5 to 8 C cooler than average for most of this forecast period, especially over the western half of the Prairies.
Alberta
Alberta will see increasing clouds spreading south from the northwest on Wednesday as the first part of a large area of low pressure moves through. Expect showers to develop late in the day on Wednesday from northcentral regions southwards toward the border.
There may be a short break in the shower activity early on Thursday before the main low moves in from B.C. This low is expected to bring plenty of clouds and shower activity for most of Thursday and Friday. With all the clouds and showers, expect daytime highs on Thursday and Friday to be only in the 8 to 12 C range with overnight lows falling to around 6 C.
It looks like it should clear out over the weekend with sunny to partly cloudy skies expected. With the return of some sunshine, expect daytime highs to warm into the upper teens with overnight lows staying in the 6 C range thanks to a cool northerly flow. A third weak area of low pressure is forecasted to move through the province on Monday and Tuesday. This will bring a return to cloudy or partly-cloudy skies and scattered showers.
Saskatchewan
The forecast for this region starts with sunny to partly-cloudy skies with the chance of the odd afternoon shower or thundershower. Temperatures look nice with highs in the upper teens to low twenties.
On Thursday, expect to see increasing clouds as the first piece of energy from the Alberta low pushes through the province. Western regions will see the best chance of showers as the impulse weakens as it moves eastwards. Daytime highs will be about 5 C cooler on Thursday thanks to the clouds.
The main area of low pressure is forecast to move into the region on Friday and bring with it plenty of clouds and showers. Best chances for rain will be over southern regions during the first half of Friday before shifting northwards later Friday and into Saturday as the low lifts. Temperatures will be on the cool with daytime highs only expected to be in the 8 to 12 C range.
It looks like there will be some clearing on Sunday as the low moves out. With the strong, late spring sunshine expect daytime highs to warm back towards 20 C. Extreme southern regions may see some clouds and showers move through on Monday as a low lift northeast out of Montana. Partly cloudy skies and near to slightly below average temperatures should return by Tuesday.
Manitoba
Manitoba is forecast to see the brunt of most systems during this forecast period. This is due to the positioning of the upper low, which allows surface lows to intensify as they get lifted north around the outer edge of the upper low.
After a soggy start to the week, this region should see a bit of a break on Thursday and Friday with partly cloudy skies and daytime highs in the 20 C range expected. Later on Friday, the southern and central parts of the province will begin to feel the effects of a low moving into Saskatchewan. Expect a couple of rounds of showers or thundershowers to move through Friday afternoon and overnight into Saturday morning.
Currently it looks like the low will lift north of the region on Saturday and bring a return of partly cloudy skies on both Saturday and Sunday. Expect daytime highs in the upper teens.
Another area of low pressure is then forecasted to lift northeastward out of Montana on Monday and bring more clouds and showers. This system looks to move fairly quickly with partly cloudy skies returning on Tuesday and Wednesday along with near average temperatures.