As we work our way slowly into fall, we are starting to see a more fall-like pattern beginning to develop — especially when it comes to overnight lows. While the upcoming forecast does not look like we see a big fall cooldown, there is more and more deviation developing between different runs of the forecast models, which means a little more uncertainty with this forecast.
With that said, the overall weather pattern is not looking that complicated over the next week. We start off this forecast period with an area of low pressure dropping southeastward out of the Northwest Territories while the persistent ridge of high pressure over the western Prairies begins to rebuild. As the low moves east, it will bring slightly unstable conditions to parts of Saskatchewan and much of Manitoba along with seasonable temperatures, while the western ridge will bring plenty of clear skies and above-average temperatures to Alberta and most of Saskatchewan.
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Over the weekend the low over the eastern Prairies will have moved off and the western ridge is forecasted to begin pushing eastward and amplify, thanks to a trough of low pressure forecasted to dig along the West Coast. This is where a little uncertainty starts creeping into the forecast. The models show the ridge of high pressure becoming quite amplified as it builds into Saskatchewan and western Manitoba. This would bring a strong southerly flow to these two provinces along with well-above-average temperatures to start the week of Sept. 18. As the upper ridge slowly pushes eastward, the trough of low pressure along the B.C. coast will start to move inland bring unsettled and much cooler temperatures to Alberta.
Alberta
Most of Alberta will see partly cloudy skies on Wednesday along with a few scattered showers as the area of low pressure over the Northwest Territories begins to drop to the southeast. Temperatures will be seasonable with daytime highs ranging from the low 20s in the south, cooling to the mid-teens in the north. The influence of this low will clear out of the province by Thursday as the upper ridge begins to rebuild across the region.
The upper ridge will bring sunny to partly cloudy skies right through the weekend along with warm temperatures. Expect daytime highs to be in the upper 20s in the south with low to mid-20s over central and northern regions. Overnight lows are forecasted to be in the low teens.
As the upper ridge pushes eastward, the tough of low pressure off the coast will push eastward, bringing an end to the above-average temperatures by Monday over the northern half of the province and by Tuesday in the south. Temperatures will drop back down into the mid-teens under cloudy to partly cloudy skies with overnight lows falling into the mid-single digits. With the passage of the trough, widely scattered showers can be expected on Monday and Tuesday.
Saskatchewan
This forecast period will start off with the Northwest Territories low bringing a mix of sun and clouds over central and northern regions on Wednesday and Thursday along with some scattered showers. Daytime highs will be mildest in the south and west, with temperatures pushing into the upper teens to low 20s. By Friday the low will have pulled off to the east and the regions will begin feeling the effect of the building upper ridge. Expect southerly winds to increase, which will help boost daytime highs into the low to mid-20s early in the weekend. As the upper ridge amplifies, temperatures will warm even further, with some weather models hinting at daytime highs pushing into the upper 20s to even the low 30s by early next week.
Uncertainty exists with just how amplified the upper ridge will become, which in turn will control how quickly it moves and just how warm it might get. Current indications are that the well-above-average temperatures will continue through most of the week.
Manitoba
After a couple of cool nights which brought some scattered light frost to a few regions, Manitoba will see a nice seasonable day on Wednesday with daytime highs in the low 20s. This nice weather will be interrupted by the Northwest Territories low as it slumps southeastward into northern Ontario by the weekend. This low is expected to bring a mix of sun and clouds to southern and central regions on Thursday and Friday, along with maybe the odd shower. It looks like the system should be out of the region by Saturday, but there a chance it may linger into early that day. Temperatures will be seasonably cool with daytime highs in the upper teens with overnight lows falling to the 4 to 8 C range.
By Sunday it looks like the western ridge will begin to impact the region. Expect sunny skies and increasing southerly winds along with warming temperatures. These sunny and warm conditions look to last right through the week of Sept. 18 with daytime highs by early in the week possibly pushing into the upper 20s, with maybe a few locations over western regions flirting with 30 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.
