Winnipeg will see a reprieve from the below-normal temperatures this weekend as the ridge of high pressure that’s brought the cooler weather shuffles off to the . In its place, a southerly flow will return warmer air to the region with temperatures climbing back to near the seasonal mark.
Over the next few days, no significant weather is expected in Winnipeg or the Red River Valley. Today will start off with some lingering cloud that will clear out through the day. Temperatures will climb to a high of around 13°C with a light southeasterly wind. Expect a low near 0°C under clear skies tonight.
Saturday will bring mainly sunny skies, light southeasterly winds and a high near 16°C. Saturday night will see a low near +2°C with a bit of cloud cover.
The RPDS weather model is forecasting highs climbing above 15°C in Winnipeg on Saturday afternoon.
Sunday’s high will also be near 16°C, however with a few more clouds than Saturday. The temperature will drop to 7°C or so on Sunday night with increasing cloudiness overnight.
Temperatures will be stuck well below-normal for late April through the remainder of the week as a stationary long-wave trough locks Manitoba into a pool of cold Arctic air. To make lemonade of it, skies will at least be quite sunny and winds light making things comparatively pleasant to how the week started.
The next two days will be very similar and very quiet weather-wise. Both today and tomorrow will bring mainly sunny skies, light winds and high temperatures near +5°C. Tonight will be another brisk evening with a low near –7°C while tomorrow night will bring slightly warmer temperatures with a low near –3°C. All of these temperatures are well below normal, though. Daytime highs will be about 8°C below normal[1], a far cry from the 10–15°C above normal we saw last week, and overnight lows will be 4–8°C below normal.[2]
The 500mb wind pattern Wednesday morning shows a highly amplified ridge over Alberta & the Western Arctic diving into a very deep trough over Manitoba & Ontario.
By Friday, the stagnant ridge-trough pattern that has set up over North America will begin to break down. Throughout the day, Southern Manitoba will increasingly come under the influence of a trough of low pressure stretching from a low tracking through South Dakota to a low lifting through Alberta. Out ahead of the South Dakota low, it’s likely that some flurries will develop along the US border in southwestern Manitoba and spread east along border regions through the day. At this point, it looks highly probable that any flurry activity will remain south of Winnipeg. That being said, Winnipeg will see increasing cloud cover and a fairly cool high of just 4°C. Clouds should clear out Friday night with a low near –4°C.
Long Range: A Shift To a Wetter Pattern?
The long range forecast is a little tricky at this point, however we can break it down into two categories of uncertainty: timing and weather pattern. The second there’s a fair amount of confidence in; the timing, however, is a lot more difficult. The current long-wave weather pattern over North America is known as a blocking pattern. These weather patterns are very stable configurations of the jet stream and other upper-level features that result in stagnant weather patterns; these can be stretches of hot, dry weather in the summer[3] or long periods of well below-seasonal temperatures.[4]
Weather models are quite good at forecast what sort of weather pattern may develop when the blocking pattern breaks down, however they are generally quite poor at the actual timing of the break-down. This is because to shift these very stable features, significant changes in the long-wave pattern have to develop across huge distances, and those changes can be very difficult to forecast accurately.
That being said, we should start to see our current weather pattern break down this weekend, driven by an approaching low that will drive a wedge into the elongated upper ridge over the west coast as well as the retrogression of an upper-level low[5] from Ontario. As this happens, cool weather will blanket much of the Prairies – although it won’t likely be any cooler than we’re seeing now – and it looks like there will be an increased chance of precipitation through the Southern Prairies, perhaps even multiple low pressure systems coming through.
All to say it’s going to go from cool and dry to cool and, quite likely, unsettled through the coming weekend. Looking even further ahead, it does look like next week we’ll see a return to seasonal temperatures.
Normal daytime highs for late-April in Winnipeg are around 13°C. ↩
Normal overnight lows for late-April in Winnipeg are around 0°C. ↩
This happens when an area gets stuck underneath a cold trough; this is what’s happening over Manitoba right now. ↩
A low pressure system “retrogrades” when it’s motion becomes opposite that of the usual motion; in our case, it’s when a low moves from east to west instead of west to east. ↩
This week’s weather will be significantly cooler than what we experienced last week as a upper-level system to our east pulls down chillier air from the north.
Cool weather will prevail on Monday under a stiff northerly flow
Monday
Today will be cool, cloudy, and precipitation-y. We’ll see some mixed showers and flurries throughout the day as a strong low pressure system exits our region. High temperatures will be in the mid single digits, meaning that even if it does snow it won’t stick around for long. Winds will be gusty due to the departure of that weather system, with values from the northwest of 40km/h gusting to 60km/h.
Tuesday
Tuesday will remain cool and breezy, but we will see some sun! High temperatures will be in the upper single digits under mainly sunny skies. Winds will be northerly at 20-30 km/h, making it feel on the chilly side.
Wednesday
Wednesday will be slightly cooler than Tuesday as more cool air pours in from the north. High temperatures will be in the mid to upper single digits, but skies will remain mainly sunny. Winds will be northerly at 20-30km/h once again
Long Range
The long range forecast suggests that this cooler pattern will stick around for at least the rest of the week. A persistent trough is expected to remain parked just to our east, meaning that cool air will be continually pumped into southern Manitoba during the short to medium-term. However, in the longer range this pattern is expected to break-down, ushering in a return of more seasonal conditions.
The unseasonably warm weather that’s been in place over Southern Manitoba will remain for a couple more days before a big shift in the weather pattern behind a low pressure system passing through on Sunday that will bring cooler air back to the region for next week. The shift in conditions will be quite a shock to the system after a pleasant stretch of above-normal temperatures looks to be replaced with the potential of a return to…snowier conditions.
Today will be a fairly pleasant day in the Winnipeg area. On Wednesday we had mentioned the possibility that today might be another very windy day but, thankfully, it looks like the system that guidance suggested would be a bit of a trouble-maker has ended up weaker and further north than it appeared earlier in the week. As such, we’ll see slightly warmer temperatures with a high near 18°C with somewhat breezy northwesterlies developing to around 30 gusting 50km/h. Tonight will bring mainly clear skies and a low near 3°C with light winds.
Saturday is looking like another beautiful day as warm air surges northwards ahead of Sunday’s low pressure system. Winds will be a bit breezy out of the south to southeast at around 20–30km/h in the morning but will likely taper off a bit into the afternoon, making for an exceptionally pleasant sunny afternoon with a high near 20°C and fairly calm winds. Unfortunately, it’s all downhill from there. Cloud will move in on Saturday evening and through the overnight period as a low pressure system pushes northwards out of the Central Plains of the United States. Expect a low near 6°C.
Sunday Brings Showers & Transition to Cooler Weather
Forecast 1000–500mb Thickness Sunday into Monday
Sunday will mark the transition into a cooler air mass as a fairly complex pattern change gets underway. The weather will be dominated by two primary features: a low pressure system lifting north-northeast out of the Northern Plains of the US and a shortwave moving into Manitoba from Saskatchewan. The two systems will undergo a complex merging and look to stall out a bit over Northern Ontario. This stalling out will resulting in an amplification of the long-wave trough developing over the region resulting in a plunge of colder air southwards over the Eastern Prairies. This is reflected very nicely in the above graphic which shows the forecast 1000–500mb thicknesses[1] plunging behind the low pressure system.
So what does that mean for Sunday? Well, there’s a bit of ambiguity as to what will happen here in Winnipeg as a lot will depend on the exact timing of and how the two systems merge. We’ll definitely see cloudy skies, likely see a very good chance of showers through the day. Precipitation will fall as rain for most of the day, but likely switch over to snow sometime in the early evening. Snowfall amounts won’t be big, however a couple cm are certainly possible.
The high on Sunday will be near 10°C with a slight northwesterly breeze. Temperatures will drop just below freezing on Sunday night. Rainfall totals of 5–10mm are possible with 2–3cm of snow possible on Sunday night.
Long Range
Heading into Monday, it looks like the Red River Vally will see flurries, highs near the freezing mark and blustery northwest winds. After that, the rest of the week looks fairly quiet with little in the way of precipitation expected. Daytime highs through much of the week will be more than 5°C below the seasonal values of 11–12°C.
The 1000–500mb thickness is the distance, or thickness, between the 1000mb level (near-surface) and 500mb level (averages around 18,000ft and is often considered the steering flow for weather systems). Higher thickness values correlate to warmer temperatures and lower thicknesses correlate to colder temperatures. ↩
