Prairie Weather (Rural Roots Canada) – Rain and frost for Alberta; sunshine on the eastern prairies this weekend.
Thursday is the calm before the change. A large area of high pressure sitting over Quebec, paired with the upper ridge still overhead, keeps Saskatchewan and Manitoba mild and mostly dry into Friday. Alberta sees the biggest swing of the three provinces. A potent low pushes in off the Pacific by Friday and works through the province Saturday, bringing rain, gusty winds, a real drop in temperature, and an end to the warm, sunny stretch producers have enjoyed the past few days. Saskatchewan and Manitoba get grazed by the edges of that system this weekend but largely hold onto drier conditions than Alberta will see.
Here’s how it looks on the weather map. You can see the Low off the Oregon coast break up as it makes landfall, then re-form over Alberta, producing rain in the central and northern parts of the province, and showers in the southeast:
WATCH FOR FROST: The average first fall frost date runs from around September 14 in the far northwest of the province to as late as September 23 in the far south, a nine-day spread across Alberta alone. The Peace has already been living on borrowed time for over a week, and now the rest of the province is reaching that average date right as an actual autumn system moves in behind this weekend’s low. Frost risk isn’t theoretical anymore; it’s arriving on schedule.
HARVEST UPDATE: Alberta sits at 22.8 percent combined as of the September 15 crop report, well behind the 57.5 percent five-year average, with the south furthest along at 46 percent and the Peace still at just 13.4 percent. Sprouting and disease pressure are starting to show up as mature crops keep getting rained on. Saskatchewan is at 32 percent as of September 14, also well off its 71 percent average, with quality grades slipping across peas, lentils, durum and barley due to excess moisture. Manitoba leads the pack at 43 percent as of the September 23 report, but the southwest has taken the hardest hit from recent rain, and there is more on the way.
Thursday
Peace Region
Thursday is a quieter day ahead of the upcoming change in the weather. Conditions will stay generally dry through the region. This is close to your last mild, workable day before the weekend system moves in, so treat it as a priority day for combining or getting canola out of the swath. High temperatures run in the mid to upper teens.
Alberta
Sunny to partly cloudy and mild under a retreating ridge of high pressure, one of the better days left in this stretch for both south and central parts of the province. Highs in Alberta reach the upper teens to low 20s, with some southern areas nudging into the mid-20s. Make use of today’s favourable weather. The pattern changes fast from here.
Saskatchewan
Aside from a few lingering thunderstorms over the far northeast early in the morning and thick fog in the southeast, the day will be mainly sunny, quiet, and mild. Highs generally run low to mid-20s. A good day for fieldwork nearly everywhere. This is what it looked like near Paradise Hill as the fog cleared out Thursday morning:
Manitoba
A weak disturbance riding along the front of the upper ridge brings a chance of cloud and a few showers, mainly southern Manitoba and the Interlake. Fog becomes a real concern overnight into Friday morning, with the Red River Valley likely seeing the worst of it, though most of southern Manitoba carries some risk. Winds stay light, which is exactly the setup that lets fog linger, so don’t count on an early start to fieldwork Friday if you’re in an affected area. Highs hold in the low to mid-20s ahead of the overnight fog.
Friday
Peace Region
This is where the weather turns. A potent low arrives and starts delivering double-digit rainfall totals to parts of the region, along with gusty winds and the chance of an embedded thunderstorm. This isn’t a passing shower system; it’s the real deal, so get anything exposed, whether that’s swathed canola or equipment, squared away before conditions deteriorate. The temperature change will be dramatic, with afternoon temperatures landing in the 5 to 7 degree range. Perhaps the only bit of good news to come out of this saturated atmosphere is that all of that moisture will prevent temperatures from reaching the freezing mark overnight.
Alberta
Cloud builds through the day as the same system pushes in from the west, with showers increasingly likely across western and northern parts of the province and an isolated thunderstorm possible over central and southeastern Alberta. The rest of southern Alberta holds onto drier, milder air longer into the day before conditions start to change. Highs still reach the upper teens to low 20s ahead of the front, but this is the end of the warm spell for Alberta.
Saskatchewan
While conditions deteriorate to the west, southern Saskatchewan sits in the warm sector ahead of the approaching Alberta low, and some western areas could approach 30 degrees, more than 10 degrees above average for late September. It won’t be record territory, but it’s a genuinely unusual reading for this point in the calendar. If you’ve got anything that benefits from a hot, dry day – spraying, desiccating, running the combine on tougher grain – today is likely your best shot before temperatures come back down and the weather changes going into the weekend.
Manitoba
The disturbance responsible for Thursday’s fog and showers largely clears out, and Manitoba holds onto mild, mostly dry conditions through the day. Highs run high teens to low 20s. Enjoy it. The next disturbance is already lining up for the weekend.
WEEKEND RAIN
The maps below show where it will rain on the weekend, and how much can be expected:
Courtesy: Pivotal Weather
Saturday
Peace Region
The low is now working through the region in earnest, bringing periods of rain, at times heavy, and widespread cloud cover for most of the day. It won’t be just wet; it will be cold, with highs remaining at or under 10 degrees. This is your wettest, coolest day of the outlook window, so plan around it rather than trying to push through it.
Alberta
Widespread cloud and periods of rain or showers move through central and northern Alberta as the low lifts northeast through the province. Southern Alberta sees less precipitation but still picks up increasing cloud and the chance of a few showers later in the day. Highs drop noticeably behind the system, generally settling into the low pre-teen double digits.
Saskatchewan
The low lifts northeastward into north-central Saskatchewan today, but the track keeps the bulk of the precipitation well north of the main agricultural belt. Northwestern Saskatchewan carries the best chance of measurable rain, while most southern and central regions stay relatively dry, aside from the odd scattered shower. Widespread rainfall is not expected across the core growing areas. Highs will range from 15 to 20 degrees.
Manitoba
Warm, moist air pushing north ahead of the Alberta low could trigger a few showers or an isolated thundershower across southern and central Manitoba, but most of the province stays dry. The rainfall shown on the map above will fall before sunrise. Regional highs hold reasonably close to seasonal values, in the mid to high teens.
Sunday
Peace Region
This is where the frost risk becomes real. Early Sunday morning, the sky is expected to be mainly clear, as high pressure starts rebuilding behind the departing low. This will allow temperatures in the Peace Region to drop to between 0 and -2. This will produce a light frost. Whether a killing frost occurs remains to be seen. It could be a sleepless night for producers with unharvested crops. During the day, temperatures will only reach 11 to 12 degrees, rather than bouncing back to earlier-week warmth.
Alberta
In central and southern Alberta, there will be frost…the question is where, and how serious. West of Highway 2, temperatures will fall to the 0 to -3 degree range early Sunday morning. There will be a light frost in many areas, but whether a killing frost develops remains to be seen. A return toward sun develops as high pressure rebuilds from the west. Highs recover somewhat but land closer to seasonal values than the unusual warmth seen earlier in the week, generally in the mid teens.
Saskatchewan
Conditions turn mainly sunny to partly cloudy as high pressure builds back in from the west. Temperatures ease toward seasonal values with highs generally in the mid-to-high teens.
Manitoba
Conditions improve further as high pressure builds in from the west, bringing mainly sunny to partly cloudy skies. Temperatures settle back toward seasonal levels for late September, with regional highs generally in the mid-to-high teens. Prior to the clearing, there will be some early morning rain in southern Manitoba. Whether it’s possible to get onto the fields during the day may depend on how much rain happens overnight. If the map above is correct, the rainfall could be significant east of Portage La Prairie, with lesser amounts to the west.
