After July temperatures in June, what next?

An area of high pressure stalled over B.C., then drifted slowly over the Prairies

After July temperatures in June, what next?

We are now just over halfway through the year, and it is shaping up to be a very interesting year weather-wise. Since it is the start of a new month, it is time to do our monthly weather summary across the Prairies, then look ahead at the different forecasts. But before we dig into that data, we must first touch on the early record-breaking heat wave that has impacted much of Western Canada.

There is not enough room to list all the temperature records that were broken — there were a lot. Instead, I will give a brief explanation of what occurred and highlight a couple of extreme weather records that were broken. Off the coast of Alaska, a large cold low developed. The flow around this low helped to spin off an area of high pressure that slowly moved into B.C., stalled for a couple of days, then drifted eastward across the Prairies, slowly weakening as it went. Think of this high as the opposite of the upper-level lows we often see stalling out over our region.

High pressure is associated with sinking air, which helps boost temperatures in two ways. First, sinking air usually means clear skies, and with the sun angle currently at its most intense, this results in a lot of solar energy. The second feature of sinking air is that the air is compressed as it reaches the ground. This heats the air further. Put these two things together with the slow movement of the high and we get record-breaking heat.

The several records I do want to talk about are the all-time Canadian heat records that were broken in Lytton, B.C., about 160 km southwest of Kamloops. The old record was 45 C, set at Yellow Grass and Midale, Sask., both southeast of Regina, back in 1937. Not only did Lytton beat the record, but utterly smashed it, and not just once, but on three consecutive days. On the third day Lytton hit an astonishing 49.6 C, which broke the original record by nearly 5 C. Usually when a national record is broken it is by a few 10ths of a degree or maybe a full degree, not 4.6 degrees! Even more impressive (if that is the right word) is that Lytton — or what is left of it after fires nearly destroyed the community — now holds the world record for hottest temperature ever recorded north of 50 degrees latitude, according to world weather temperature record expert Maximiliano Herrera.

With two June heat waves this year, I think it is safe to say that June was a warm month across the Prairies. All major centres reported above-average temperatures for the month. The warm spot compared to average was Calgary, which came in at 3.3 C above average. The cold spot, if I can use that term, was Regina, which came in 1.7 C above average. Looking at absolute temperatures, the hot spot was Winnipeg, with a mean monthly temperature of 17.9 C, which is what Winnipeg would normally expect to see in July. The cold spot was Edmonton with a temperature of 16.8 C.

Precipitation, as is usually the case when it is hotter than average, was below average across most locations. With most of our summer rainfall coming in the form of thunderstorms, amounts can be variable over short distances. In Alberta, all three centres were dry, reporting amounts that were between a third to a half of their long-term averages. Saskatchewan saw below-average amounts in the Saskatoon region, with near-average amounts in Regina. Across agricultural Manitoba the Winnipeg region reported dry conditions, with amounts coming in at less than half the average. To the west, Brandon recorded slightly above-average amounts thanks to a heavy thunderstorm earlier in the month. These same thunderstorms help to push Dauphin’s rainfall total to within about 10 mm of average.

Who called it?

Overall, it was a hot and dry month across the Prairies. Looking back at the forecasts I would say that the winner for June would be NOAA. Its forecast called for “above-average temperatures from June through August with below-average precipitation over the western and central Prairies and near average over Manitoba.” Not too bad!

The big question is, will we continue to see heat waves and dry weather in July and August, or will cooler and wetter weather move in? Starting off with the almanacs (which were way off in June), the Old Farmer’s Almanac calls for a slightly warmer-than-average and dry July, followed by a very warm and wet August. The Canadian Farmers’ Almanac looks to be calling for cooler- and wetter-than-average conditions as it mentions unsettled and stormy conditions with the odd mention of cool.

Moving on to the weather models: last month’s winner, NOAA, forecasts a continuation of above-average temperatures, with the warmest readings over far-western regions. Western regions are also forecast to see below-average rainfall, with amounts closer to average as you move eastward. The CFS model calls for above-average temperatures in both July and August. This model is also forecasting below-average precipitation. The final weather model, CanSIPS, is calling for a very warm and dry July followed by a warm August, but with precipitation near to slightly below average. Not the best forecasts by any of the computer models.

My forecast — or guess, as I like to say — is leaning toward the computer models. I would not be surprised if we see at least one more heat wave this summer, possibly another record-breaking one. So, warm and dry is what I am going with, while crossing my fingers that we all get a few timely thunderstorms. Until next issue, keep cool and hope for rain for those who need it.

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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