Prairie Weather (Rural Roots Canada) – Hot, humid, and sometimes stormy. This week’s forecast reflects a change in the weather pattern, and just in time. The welcome rainfall of the spring and early summer provided the moisture needed to get the crops in production. However, what many say is needed now is a period of warmer, drier weather, to help the crops thrive. And that’s exactly what we’re going to get. In fact, there are long term signals that dry and warmer than average weather will persist through the rest of July.

The hottest day of the week is expected to be Wednesday, with temperatures across the prairies exceeding 25, easily reaching 30 in much of Saskatchewan and Manitoba, and in parts of Alberta, temperatures could rise beyond 35 degrees in the afternoon. This map shows expected temperatures in the late afternoon on Wednesday. The areas in bright red show highs between 35 and 40:

RELATED: Hail Report: Crop Damage Claims Reach 1,500 for June 17-23

The hot air being is being drawn into Western Canada by an upper ridge of high pressure centred in California. The flow of hot air will also contain substantial moisture. It will be sticky, as high humidity will make it feel even hotter. High humidex values are forecast for eastern Alberta and southern Saskatchewan on Thursday, for southern Saskatchewan and central and southern Manitoba on Friday, and for southern Manitoba on Saturday. With the humidity, it will feel hotter than 40 degrees. There will be warnings and advisories from Environment Canada.

This is not to say there won’t be rain. There will, but most of it will come from thunderstorms, rather than from organized Low pressure systems. So, rain totals will be relatively small, but storms, especially in Saskatchewan and Manitoba during the times of high humidity, could be both frequent and severe.

As mentioned, the warmer weather is coming at the perfect time. Not only are the fields green, but the rivers are full. The Bow River, on July 6:

The Bow, like many other prairie rivers, is running high, but not overflowing, and within its normal range for early summer:

Courtesy: rivers.alberta.ca

The warmer weather is also coming at the perfect time for delayed crops. Crop reports from Alberta and Saskatchewan indicate, that after a strong start, the growth of several crops has been delayed by the persistent cool, wet weather. The sunnier, warmer weather of this week is very much needed.

Prepare for a hot week, especially in Alberta, where 30-degree readings are expected each day in parts of the south.

Monday:
Anticipate hot weather in much of Alberta and Saskatchewan, with high humidity. Thunderstorms are expected in extreme southern Manitoba. Highs will reach the mid-twenties across the prairies, but in Alberta, highs of 30 are likely in most areas.

Tuesday:
The hot weather continues, especially in Alberta and Saskatchewan, where highs above 30 will be common. Highs of 25-30 are likely in Manitoba, where afternoon showers and thundershowers are possible from the Interlake to the US border.

Wednesday:
This is the hottest day of the week, and, so far, for the year. And it’s the day the fun begins, with the upper ridge from California breaking down, destabilizing the atmosphere. Expect afternoon thundershowers to pop over the Alberta foothills and drift eastward. The storms will weaken as they cross central Alberta, from Didsbury northwest to the Peace. There is a chance these storms would become severe, with hail, and possible tornadoes.

Thursday:
The atmosphere, especially in Saskatchewan and Manitoba will start to feel “juicy” – hot, with high humidity. Thunderstorms may become severe over the central prairies, again with hail and possible tornadoes. It will again be uncomfortably humid for many, with humidex values making feel hotter than 40.

Friday:
The severe thunderstorm threat moves slightly eastward, and on Friday, we can expect severe thunderstorms in the southeastern prairies. A low pressure system in northern Alberta will generate some steady rain along the Alberta, Northwest Territories boundary, and that rain will extend to another Low in central Manitoba. The agricultural south will remain hot and dry – for the most part. Showers are possible in central Alberta before sunrise, with afternoon isolated thunderstorms possible along the Alberta foothills, and in southern Saskatchewan.

Saturday and Sunday:
By Saturday, the severe thunderstorm threat will likely be strongest in southeastern Manitoba and northwestern Ontario. A new Low forms in southern Alberta Saturday, generating showers and thundershowers. By afternoon, the greatest rain threat will be between Rosetown and Swift Current, as the Low moves toward Saskatchewan. By Sunday, the Rosetown rain will have moved into southern Manitoba, and another weak low forms in west central Saskatchewan. Showers will wrap around that low, and reach central Alberta by the afternoon. 30 degree highs are possible both Saturday and Sunday in southern Alberta, with the rest of the prairies likely to reach the mid-twenties.

There have been several references above to the humidex. It’s a term not used much in western Canada, where the weather is commonly dry, and humidity is low. The term is used frequently in eastern Canada. It refers to how warm it feels when humidity is high on a hot day. Want to know more? This is from Environment Canada’s glossary:

COMPARE TO LAST WEEK: Prairie Weather this Week: July 1