Prairie Weather (Rural Roots Canada) – Big weather transition this weekend, with rain and snow on the way

On Thanksgiving weekend, Alberta gets rain and snow,  while Manitoba and especially Saskatchewan, get walloped with heavy rain.   (weather forecasters don’t use the word “walloped” lightly).    A vast majority of the harvest has been completed, but those who still have work to do will want to take advantage of the benign weather Thursday and Friday, before this weekend’s big weather change.  That change will bring wet weather, from which the fields may not quickly recover.

This map shows expected snowfall up until Sunday evening:

A strengthening Pacific trough/low is expected to develop over the northern US this weekend and lift northeast into Saskatchewan/Manitoba late Saturday into Sunday — this brings a risk of heavy rain (locally 30–50+ mm), strong winds and, where colder air wraps in, wet heavy snow in  much of Alberta and western/north-central Saskatchewan.   The snow is expected on the weekend, after the ridge of high pressure that has maintained sunshine moves east.

Rain is also expected in many of the same areas, in addition to the snow.   The map below shows areas that can expect rain, also up to Sunday evening.  Note the above mentioned heavier rain for southeastern Saskatchewan and parts of Manitoba:

Also on the map above, check out what looks like a doughnut on the bottom left side.  That’s a cutoff low in the eastern Pacific that feeds the moisture into the Western US, British Columbia, the Canadian prairies.   This feed of moisture from the southwest, plus an influx of colder air from the north is what will produce this weekend’s snow in Alberta and Saskatchewan.

Thursday

Alberta, Saskatchewan, Manitoba

High pressure both at the surface and aloft will keep the sky clear, and the weather dry across the prairies Thursday.   A few sprinkles of rain can be expected in the northern forests of Saskatchewan and Manitoba, due to a weak disturbance.  Rainfall amounts will be minor.    Highs in Alberta and in the southern halves of Saskatchewan and Manitoba should reach the low to mid teens.   In the northern halves of Alberta and Saskatchewan, highs will remain in the high single digits.

Friday

Alberta, Saskatchewan, Manitoba

Conditions remain ideal for field work Friday, with continued sunshine across the prairies, and warm weather.  In Alberta, expect highs in the 15 to 20 degree range…same for most of Saskatchewan.   However, there is a chance for even warmer weather,  with highs in the low 20s from Moose Jaw to Rosetown.   Southwestern Manitoba will see highs in the 15 to 20 degree range, with highs of 10-15 elsewhere.   A low develops in northwestern Alberta, and this will help the weather change course over the weekend.

Saturday

Alberta

The low that develops in northwestern Alberta Friday, strengthens and moves eastward toward Saskatchewan.   As it does, it will drag a rather strong cold fron across northern and central Alberta.   The front will bring wet weather.   By the afternoon, expect rain between Calgary and Edmonton.   In the foothills and mountains of central Alberta, as far north as Grande Prairie, there will be snow. Snow showers are also expected in northern Alberta, as the circulation around the Low draws cold air into the region.  In southern Alberta, a westerly wind should keep the area dry, but if there is a southward deviation in the track of the cold front, showers cannot be ruled out during the day.    Rain will develop in the south later in the day as the front reaches the area during the evening.  Due to the cold front, northern Alberta’s high temperatures will remain in the single digits, cooler at higher elevations.   If the front goes along it’s expected path, southern and southeastern Alberta could warm to the high teens.

Saskatchewan

The low and front that causes such an abrupt change in Alberta’s weather on Saturday will have the same impact in norhtwestern Saskatchewan, bringing rain to the area.   Central and southern Saskatchewan will not be affected by this system on Saturday, but another low in the northern US bears watching.    It may bring some rain across the border into southwestern Saskatchewan late in the day.   Another impact of the low is that on its east side, it will draw some very warm air into southern Saskatchewan.   Expect highs across the area to reach the low 20s.   Immediately south of Regina,  temperatures could even climb to the high 20s.

Manitoba

The Low crossing the northern prairies is not expected to have much impact on agro-Manitoba.   Rain from the low will stay to the north.  However, a Low pressure system in Montana will bring rain to southern Manitoba on Sunday.   Before that, on Saturday, it will bring a surge of warm, humid air into the region.  Expect increasing cloud and showers late Saturday, with a risk of thunderstorms in the warm sector. Rainfall could be moderate to heavy in places.  High tempeatures across most of Manitoba will reach the high teens.

Sunday

Alberta

Active weather continues across Alberta Sunday with rain and snow.   Field operations will be limited.   Don’t get stuck in the mud!    It will be cooler with showery conditions in the foothills and southeastern zones.  There is a chance for mixed precipitation (rain, wet snow) in higher elevations and some southern and eastern parts of the province where cold air is stronger.   This map shows the moisture expected on Sunday alone:

On the map above, blue is where snow is expected.  Green is rain.   It is entirely possible the area of snow will expand eastward beyond what is shown on the map.   The map has rain for the Lethbridge area.   Don’t be surprised to see some snow there as well.  The amounts don’t look like much, and this is not a heavy precipitation day for Alberta.   However, south of Edmonton, expect wet weather through most of the day.   It will be a cold day across Alberta, with highs in most areas ranging from 0 to 5 degrees.

Saskatchewan and Manitoba

The Montana low crosses the border, and brings heavy rainfall to southern Saskatchewan and across southern Manitoba Sunday.  The wind will be strong as the storm moves through.  The map below shows rainfall amounts expected Sunday alone:

The dry area near Boissevain in southern Manitoba is the location of the centre of the Low Sunday afternoon.   It’s expected to be a strong low (989 mb), with a tight pressure gradient, so there may be enough wind to blow the rain sideways.    It will be surprisingly warm on the east side of the low.   Despite the rain, temperatures could climb into the high teens across southern Manitoba.

Confidence in the above forecast is medium to low.   Any shift in the tracks of either or both Low pressure systems could alter our expectations.    This is Thanksgiving weekend and there will be a lot of travel.   Farmers and travellers alike are urged to consult up to date forecast from Environment Canada before heading out.

Harvest:

Until this weekend, the weather across most of the prairies has been ideal for harvest, and the numbers have been impressive.  A few days ago, Olivia Taylor posted this story on the 2025 harvest.  And while I can’t take credit for it, it has been a pleasure giving farmers good news over the harvest season.