Prairie Forecast: Large Hudson Bay low dominates

As the weather models correctly predicted, a large and extremely strong area of low pressure formed over Hudson Bay during the last forecast period, bringing the expected cool and unsettled weather to the eastern half of the Prairies. Over the western half of the Prairies a weak upper-level ridging brought, for the most part, sunny and dry weather along with seasonable to warm mid-summer temperatures. For this forecast period, it looks like the Hudson Bay low and the western upper ridge will continue to be the main driving forces.

The Hudson Bay low as of Wednesday (July 12), is spinning over Hudson Bay — and is literally the size of Hudson Bay. This low is forecasted to begin retrograding back to the west, then drop southward into northern Ontario over the weekend. This means the eastern half of the Prairies will continue to be under the influence of this low. Meanwhile over the western half of the Prairies, the upper ridge will continue to bring nice summer weather, at least until the end of the week. Around Monday (July 17) the weather models show an area of low pressure forming over central Alberta which could result in some unsettled weather to end this forecast period.

Alberta

Alberta’s weather will be under the control of the weak upper ridge. The combination of the weak flow, smoke from forest fires, and regions of high surface moisture make for a bit of a tough forecast for temperatures. Temperatures look to be seasonal with daytime highs to be the mid-20s and overnight lows falling into the 12 to 14 C range. Areas that see heavier smoke will be cooler while those with bright sunshine will likely be a bit warmer. There will be enough energy around to trigger short-lived afternoon thunderstorms on any given day.

By July 17 the weather models show an area of low pressure spinning up over central regions. Confidence in this is not that high, so watch for updates over the weekend. Should this develop, expect cool showery weather for central and northern regions from the 17th to the 19th. In the extreme south, the southerly flow ahead of this system will bring hot weather into the region, with daytime highs pushing into the low 30s.

Saskatchewan

Much like we saw in the last forecast, this region will continue to be sandwiched between the two main weather makers. As the Hudson Bay low drops southward from July 12 to 16, cool air will try to push in from the east. Expect seasonable summer temperatures to start off, but as the low drops southward, temperatures will cool toward the low 20s by the weekend. The coolest temperatures will be over eastern regions. Don’t expect much in the way of precipitation, with maybe the odd shower or thundershower in eastern regions over the weekend as the coolest air slides by.

For the start of the week of July 17, temperatures will warm back up into the mid- to upper 20s ahead of the developing Alberta low. This low looks to lift northeastward by July 19, bringing the chance of showers or thunderstorms as it tracks by.

Manitoba

It looks like Manitoba will see the worst weather during this forecast period — unless you like cool, windy, unsettled weather. As pointed out, the Hudson Bay low is forecast to drop southward into northern Ontario over the next several days, finally moving off to the east late in the weekend. Most of the cool unsettled weather will remain in northern Ontario, with more northern and eastern regions of Manitoba seeing the best chance of showers and thundershowers. The best chances for precipitation will be late on Thursday and then again on Sunday. Temperatures will be seasonably cool with daytime highs in the 20 to 25 C range — warmer in the west, and cooler in the east and north.

To start the week of July 17, the upper low looks like it will finally move off to the east and Manitoba will warm back up to more seasonable temperatures. There are some indications of unsettled weather moving in around the 19th or 20th as an area of low pressure forms to our southwest — but that is a long way off, so watch for updates.

— 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.