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Forecast: A fall heat wave approaches

Covering the period from September 16 to 25, 2019

This map shows the total amount of precipitation that fell across the Prairies over the 30 days ending Sept. 11 as a per cent of the long term average. Most of Saskatchewan and Manitoba have seen near- to above-average rainfall while a good portion of Alberta has seen near- to below-average amounts.

The first half of last week’s forecast played out pretty well; we did see rain move through early in the week, followed by a second system on Thursday and Friday. What didn’t pan out were the milder temperatures with the second system. Lucky for us, the weather models didn’t do quite as well for the second half of the forecast — so we haven’t seen much frost just yet.

This forecast period will begin with a strong ridge of high pressure over the central part of North America and a strong, stationary low spinning up well to our west. This setup will bring the first fall heat wave to our region with plenty of sunshine along with warm temperatures. Daytime highs from Monday to Wednesday are forecasted to be in the mid- to upper 20s and I wouldn’t be surprised if we see a few low 30s. Along with the heat will also come humidity, with humidex values pushing into the low to mid-30s. Anytime we get heat and humidity there is always the potential of seeing some thunderstorms.

The ridge of high pressure is forecast to break down starting on Wednesday as the western low begins to push to the northeast. The current track of this low takes it into Saskatchewan on Thursday and then through north-central Manitoba on Friday. This track would mean southern and central regions remain on the mild side, with daytime highs in the low to mid-20s and overnight lows around 12 C. We will likely see a mix of sun and clouds, with the best chance of showers over western regions and northern regions due to their proximity to the low.

Over the weekend a weak area of high pressure will build in, bringing sunny skies and mild temperatures. The weather models then show an area of low pressure tracking southeastward across northern Manitoba. This system could trigger a few showers or thundershowers sometime on Sunday as a cold front drops southward behind the low. Cool high pressure is then forecast to move in during the first half of next week, bringing sunny skies along with the chance of some frost.

Usual temperature range for this period: Highs, 12 to 22 C; lows, 2 to 10 C.

About the author

Co-operator contributor

Daniel Bezte

Daniel Bezte is a teacher by profession with a BA (Hon.) in geography, specializing in climatology, from the U of W. He operates a computerized weather station near Birds Hill Park.



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