Unsettled Monday, Then A Return to Calmer Conditions

Today will be rather unsettled across the Red River Valley as a trough of low pressure moving through the regions supports scattered showers and thunderstorms. After it passes, though, an omega block begins to develop, bringing more settled weather to the region.

Today’s main weather will be two rounds of showers that move through the Red River Valley. The first round will be early this morning, a continuation of showers and thunderstorms that developed in Saskatchewan last night and have pushed eastwards overnight. There is a chance we’ll also see some embedded thunderstorms with this band as it moves through. General morning rainfall will be around 5-10mm in many areas, but due to the convective nature of the precipitation there will be significant variability, with some areas potentially seeing nothing and others seeing higher amounts.

The second wave of showers will develop in the afternoon as a second low pressure centre moves through the region. This band will likely be more focused that the morning activity and primarily impact areas south of the bulk of the morning activity.

Aside from the rain, conditions will be fairly cloudy, although there may be an odd sunny break between the two batches of showers. Temperatures will be mild with a high near 19°C, but winds will be breezy out of the southeast at around 30 km/h. Temperatures will dip down to around 8°C tonight with clearing skies and winds flipping around to the northwest at 10-20 km/h.

Tuesday and Wednesday with both be much sunnier days with north to northwesterly winds. Tuesday will bring a high near 18 or 19°C with temperatures then dropping to a low near 7°C. Wednesday has quite a bit of uncertainty regarding the daytime high. The developing omega block will be pumping warmth across the western Prairies towards Manitoba, but an upper-level low will be moving westwards from Eastern Canada, pushing cooler temperatures into Manitoba from the east and northeast.

This will create a fairly sharp temperature difference somewhere across the southern part of the province, and with a relatively quick change from 19-20°C in the warm air to around 5°C in the cold air. Winnipeg looks to lie in the middle of this zone, with a high likely near 14°C, but a minor shift of this boundary to the north or south would substantially change the expected high temperature.

Long Range

The weather will continue fairly quiet through the remainder of the week with the cooler temperatures mid-week giving way to highs back near 19-20°C for Winnipeg by Friday. The weekend looks mild, but a chance for showers returns to the region on Sunday.

Winnipeg’s seasonal daytime high is currently 18°C while the seasonal overnight low is 4°C.

Temperatures will be seasonably cool in the Red River Valley through the remainder of the week with the chance of showers returning to the region.

Today will be fairly pleasant, all things considered, with a fair amount of sunshine until cloud cover moves in through the mid- to late afternoon ahead of a low pressure system lifting northeastwards out of the Northern Plains. Temperatures will climb to around 20°C this afternoon.

Tonight will bring showers and/or thunderstorms to Southern Manitoba, however the exact distribution of the precipitation remains a little uncertain. Two features will support rainfall: the main upper low which will track through WestMan & the Interlake and a secondary shortwave that will lift through North Dakota. What begins as a large line of rain will likely focus towards these two features overnight. This means that here in the Red River Valley, amounts will likely be less, or even non-existent, compared to areas to the west/north or south/east. The primary chance for rain will occur between around 9PM to 4AM. In heavier showers, 15-25mm of rain could be seen, while many places will likely see 5-10mm. Again, here in the Valley, we may escape with little precipitation, depending on how things develop. Expect a low near 12°C.

Thursday will bring mixed skies with a high once again near 20°C. The day will be otherwise fairly unremarkable. Expect more cloud and a low near 11°C. All in all a pleasant first day of school!

Friday will see another disturbance move across Southern Manitoba, bringing another chance for some scattered showers under mainly cloudy skies. Sunshine should start poking out through the afternoon as skies become more mixed behind the disturbance. Expect a high near 18°C. Skies will clear overnight as temperatures dip to around 9°C. Some lake-effect showers are possible overnight in the lee of both Lake Manitoba and Lake Winnipeg as cool northwest winds roll over the warm lake surface.

Long Range

The weekend is looking fairly dry with variable cloudiness and daytime highs in the upper teens or low twenties. Sunday will likely be windy out of the south. Overnight lows will continue near 10°C.

Winnipeg’s seasonal daytime high is currently 20°C while the seasonal overnight low is 8°C.

After a warm but windy day in Winnipeg & the Red River Valley today, the weather will turn unsettled for the weekend as multiple low pressure systems move through the province.

Today will be a warm and windy day over the Red River Valley. Temperatures will climb to a high near 27 or 28°C while strong southerly winds develop over the region ahead of a strengthening low pressure system in Saskatchewan. Winds near 30 km/h this morning will strengthen to 40 gusting 60 km/h by midday. That should be as strong as they get, however there is a slight chance that winds may reach as strong as 50 gusting 70 km/h.¹ We should see plenty of sunshine, although by the second half of the afternoon some cloud cover will begin working into the region.

Tonight will be mild with plenty of cloud cover and windy conditions continuing. Winnipeg will see a chance of showers or thunderstorms overnight as the first weak impulse of many moves through. Expect a low near 18°C.

Saturday will bring fairly cloudy skies, albeit with a few sunny breaks likely in the morning, and a chance of showers or thunderstorms as a cold front pushes into the Red River Valley, slowing down and stalling out through the day. Winds will start out around 30 gusting 50 km/h and then taper off as the front moves into the valley. Temperatures will reach a high near 26 or 27°C.

Any shower or thunderstorm activity will slowly move towards the southeast through the evening, however may only barely make it east of the Red River Valley by morning.

Sunday brings with it some uncertainty, but will likely be a wet day. For the first time in quite a while, we’ll be dealing with a Colorado Low moving through North Dakota and into northwestern Ontario. This system will push the front that passes through on Saturday back to the northwest, developing an area of rain that stretches from South Dakota all the way through Manitoba. How far west the rain will push remains an uncertainty; many models suggest the rain pushing northwest of Winnipeg with anywhere from 20-40 mm likely² while others keep the entire area of rainfall just to the southeast of Winnipeg.

In either of those outcomes, it’s still quite likely that areas to the south of Winnipeg, particularly in the southern Red River Valley³ will see accumulating rain along with breezy winds out of the northeast.

Temperatures will be cooler on Sunday with a high near 22°C. The rain should taper off by Monday morning with temperatures dipping to a low near 12°C.

Extended Forecast: Labour Day Monday

Monday will be a fairly cloudy day with cool conditions left in the wake of the Colorado Low. Winds will be breezy out of the north as temperatures climb to a high near 19°C. There will likely be a continued chance of showers, but nothing to the extent of what will be seen in places on Sunday. Monday night looks to bring another chance for showers or thunderstorms ahead of yet another disturbance moving into the region.

Winnipeg’s seasonal daytime high is currently 21°C while the seasonal overnight low is 9°C.