Prairie Weather (Rural Roots Canada) – Strong storms, heavy rainfall for the eastern prairies – cool and wet in the west

A broad pattern change is underway across Canada. The western prairies will continue  to cool, while Eastern Canada heats up. As the clash between cool and warm air masses intensifies over the prairies, low pressure systems are developing , setting the stage for rainfall and thunderstorms, including the risk of severe weather and localized flooding.

A significant system is expected to form over the southern Prairies by Friday-Saturday, drawing in hot, humid air from the south, especially into southeastern Manitoba.

The following map shows expected rainfall totals between Wednesday evening, and midnight Sunday night:

Here is a better look at rainfall amounts expected over the same time period in Alberta:

Thursday

Alberta

Showers or periods of rain will persist across Alberta Thursday, except for the far north.   There will be some breaks in the rain from time to time, especially in southern Alberta during the midday.   The rain will be constant, though, between Athabasca and Peace River,  and will then return to southern regions in the late afternoon and evening.   Thunderstorms can be expected overnight and into Friday morning in the Calgary area west toward Canmore, and in east central Alberta from Slave Lake southeast to Lloydminster.  Funnel clouds are possible in east central Alberta, because of instability and weak wind aloft.  Because of the widespread wet weather, it will be much cooler than average, with highs across most of Alberta in the mid teens.

Saskatchewan

Cloud will continue to build across the grain belt of southern Saskatchewan during the day, with rain moving in from the southwest.   Within this area of rain, there may be thundershowers, some of which may be strong to severe. By midday,  expect rain across southern Saskatchewan, expanding northwest by late afternoon.   Funnel clouds are possible between Meadow Lake and Kindersley.   The weather pattern has changed, and the dry weather anticipated for southern agricultural regions Thursday is no longer expected.  It will be cool, with highs across most of Saskatchewan reaching the 15-20 degree range.

Manitoba

A low pressure system moving from northeastern Manitoba to northwestern Ontario will provide rain to the northern half of the province on Thursday.  Southwestern Manitoba will see thunderstorms developing later in the day, some of which could turn severe, especially near the US border. Main risks include strong winds, heavy rainfall, and possible localized flooding.  These storms in southern Manitoba will be fueled by heat.   Most parts of the agricultural south can expect temperatures to reach the high 20s.   Humidity will be high, and it could be exceptionally muggy in the Red River Valley, where some areas may reach 30 degrees or higher.

Friday

Alberta

South of Edmonton, Friday will be a rainy day across the southern half of the province, as a Low pressure system slides southward in Eastern Alberta, parallel to the Saskatchewan boundary.   Another storm system develops along the foothills.  The rain will be widespread,  with amounts in localized areas reaching 50-75 mm.   The heavier amounts of rain will occur in strong thunderstorms, and if the rain comes down hard enough, localized, brief, flooding is possible.   Because of the wet weather, it will be cool, with temperatures in much of southern Alberta remaining below 15 degrees.    In the foothills it will be even colder, with highs between 5 and 10.    In northern Alberta,  away from the rain, highs will reach the low to mid 20s.

Saskatchewan

It’s a cooler than average day in Saskatchewan, with highs between 15 and 20 degrees.   It will be a day of showers and storms across southern Saskatchewan, fuelled by a low pressure system just across the boundary in Alberta.    Rain will intensify during the day, with thunderstorms expected to last well into the evening, especially in a west-east band just north of Saskatoon.   The northern third  of Saskatchewan will remain dry.

Manitoba

Because of an abrupt change in the weather pattern, the outlook for southern Manitoba has flipped from warm and dry to hot and wet.  It will rain all day long in the interlake and southern Manitoba.  But there’s more….   A developing low pressure system will draw in hot, moist air, leading to a high humidex and oppressive heat in southeastern Manitoba.  Severe thunderstorms are expected, particularly in the southeast and along the US border.  These storms could produce strong winds, torrential rain, hail, and localized flooding.

Saturday

Alberta

As a low pressure system reponsible for the recent rain moves to Manitoba,  the rain in Alberta begins to taper off Saturday.   Only the eastern side of the province can expect all-day rain.   It will be a dry day elsewhere.  However, evapotranspiration and  instability in the afternoon could lead to showers and storms developing over the foothills.  Severe weather is not expected.  There will be a north wind, and the air mass is cool, so most areas will see highs only near 20 degrees at best.

Saskatchewan

It will be another rainy day in the southern half of Saskatchewan, as the Low pressure system that has produced several days of wet weather intensifies as it moves into Manitoba.   Plenty of rain will be hanging back across Saskatchewan,  and isolated thunderstorms can’t be ruled out.   Only the northern third of the province will remain dry.   In some areas, particularly near the Manitoba boundary, the heavier rain will limit high temperatures to the 10-15 degree range, but most of the rest of the province has a good chance to reach 20 degrees.

Manitoba

Manitoba is home to the big weather show of the weekend, as a Low pressure system strengthens in the north, spreading rain back west to Saskatchewan,  and along Manitoba’s western boundary.   Southern Manitoba will experience showers, especially in the afternoon.   A flooding risk remains in areas that received heavy rain Friday. There will be a significant temperature change as the oppressive heat of Friday gives way to much cooler weather Saturday, with highs near 20.

Sunday

Alberta

Sunday will be a dry and sunny day across southern Alberta, with building cloud and afternoon showers returning in central regions.  As always at this time of year, thunderstorms can’t be ruled out, but severe weather is not expected.  The return of dry, stable conditions in the south will bring about a significant warmup.    Temperatures south of the Trans Canada Highway could reach the 25 to 30 degree range.   Elsewhere in Alberta, highs should reach the mid 20s.

Saskatchewan

The agricultural south will remain quiet and dry Sunday.  In central regions, a north south band of showers may develop during the day along a warm front emanating from a Low in the Northwest Territories.  Warm frontal precipitation is characteristically light,  however, storms may be possible, given enough instability.   In southern Saskatchewan, this will only affect areas east of Regina, and late in the day.   Across the province, expect highs from 20-25.

Manitoba

Warm weather is back, especially south of the Assiniboine River, where highs of 25-30 are possible.   It will be only slightly cooler elsewhere in southern Manitoba.   Most of the south will have a sunny, dry day.   However, from the interlake all the way north, and in the Whiteshell, expect rainy weather.   This is due to a strong, but departing Low pressure system just south of York Factory.    We’ll begin to see the backside of this very wet weather system early next week.   It leaves behind saturated ground across much of Manitoba.

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