Unseasonably warm air will remain in place over Southern Manitoba for another day before a disturbance pushing eastwards across the Prairies brings a chance of rain and more seasonal temperatures for Tuesday. The “cool-down” will be short lived as above-seasonal temperatures are expected to return on Wednesday.
For the 42nd Canadian general election today, weather couldn’t be nicer for late October in Winnipeg. Today will bring plenty of sunshine and light winds with a high near 15°C.1 Temperatures will be cool tonight at around 2°C under increasing cloudiness.
The RDPS shows precipitation pushing into southern Manitoba late Tuesday afternoon.
Tuesday will be a mainly cloudy day with a cool northeast wind limiting our high to a more seasonal 9°C or so. There will be a chance of some shower activity through the afternoon and overnight period as a trough of low pressure pushes across the region, however amounts from the precipitation are expected to be fairly minimal with just a couple mm likely at most. With cloudy skies overnight, the low temperature will be kept a bit warmer at around 4°C.
Wednesday will see a return of the warmer weather. Skies will clear through the morning hours letting the sun work a little bit of it’s late-season magic and bring us towards a high near 11°C with relatively light winds. Expect a low near the freezing mark on Wednesday night under clear skies.
Long-Range Outlook
The second half of the work week looks quite pleasant with mainly sunny skies Wednesday & Thursday and warmer-than-seasonal daytime highs in the low teens. Many weather models show a large low pressure system ejecting northeastwards out of Wyoming on Thursday night and pushing through Southern Manitoba on Friday, bringing a swath of rain across the region. There’s still quite a bit of uncertainty associated with that system, though, so we’ll keep eyes on it as the week goes on and take a closer look at it in our mid-week forecast!
This is 7°C above the seasonal high temperature of 8°C for this time of year.↩
The warmer-than-seasonal warmth in place over Southern Manitoba will last just one more day before a cooler air mass works its way into the region behind a cold front that will push through on Thursday.
Today will bring seasonal weather to Winnipeg & the Red River Valley, albeit with a bit of a breezy wind. Under mainly sunny skies, the temperature will climb to around 15°C, which is nearly 5°C above the seasonal average high of 11°C for this time of year. Winds will pick up through the day and be fairly windy out of the northwest with sustained winds climbing to 30–40km/h with gusts to around 50km/h.
Temperatures will dip to around 4–5°C tonight with skies becoming partly cloudy before morning.
Thursday will be quite an unpleasant day that will see a cold frontal passage that will bring in blustery winds and falling temperatures. The day will start off with partly cloudy skies and temperatures climbing to around 10–11°C by midday. Winds will be windy out of the northwest at around 30km/h with some gustiness on top of that. As the cold front passes through in the afternoon, we’ll see mixed-to-cloudy skies develop with a very slight chance of some showers along the front as it passes through. No significant accumulations are expected. Winds will remain blustery with winds remaining at 30–40km/h with gusts as high as 60km/h.
Looking at the forecast 850mb temperatures, the passage of the cold front on Thursday is quite obvious.
As the front passes through, temperatures will drop to around 6°C in the Red River Valley. They’ll continue to drop as winds taper off and skies clear, heading towards an overnight low near –2°C.
Friday will be a pleasant, but cool, day. Winds won’t be much of an issue and temperatures will climb to around 7°C under mainly sunny skies. The low on Friday night will once again be around –2°C under clear skies.
Unremarkable Weekend Ahead
Looking ahead to the weekend, there doesn’t appear to be much to say about it. Through the weekend temperatures will climb back towards seasonal values with a bit of wind on Sunday. No significant precipitation is in store for the region.
Next week looks to have a bit of variability to daytime highs and a couple chances for rain as a slightly more unsettled pattern develops.
An incredibly abrupt change is in store for Southern Manitoba as a powerful low pressure system is set to blast the near-record warmth out of the region and replace it with unquestionably fall-like weather. As it often is in the shoulder seasons, though, it’s going to be quite the spectacle.
Temperatures have soared into the mid–20’s quickly this morning, rapidly approaching the record high for Winnipeg of 26.1°C set in 1941. A powerful low pressure system to our northwest is approaching, though, and it is going to pack a mean cold front.
Surface analysis valid 12:45PM October 11, 2015
The midday surface analysis shows us three primary features. The first is the frontal wave with warm front across the northern Interlake and cold front draped southwards along the Manitoba/Saskatchewan border. To the southeast of these fronts is the unseasonably warm air mass that is bringing very warm temperatures to the region. The second feature is a low pressure center over central Saskatchewan. The last is a broad cold front that stretches from Central Alberta into Northern Manitoba.
Important to note is that the low pressure centre has occluded[1] and that there is a trowal developing (visible on the satellite image). This lonely low will trundle along for a little bit, until it can re-attach to the cold front slumping down behind it. The temperature gradient along the northern front is actually quite significant, and as the low re-attaches to that frontal wave, it will rapidly intensify. This low will move east-southeast as the steering flow amplifies and digs the upper-level trough.
While we may warm another degree or two, it’s more or less all downhill from here. Wind will continue to pick up out of the west-northwest late this afternoon to around 30km/h as an area of showers blossoms over Southern Manitoba. Widespread shower activity is likely much of the night as strong cooling aloft results in persistent destabilization of the atmosphere. Winds will remain around 30km/h with gustiness on top of that.
The real story will be when the cold front slams through early tomorrow. More rain is likely with the passage of the front, but winds will be the primary issue. As the cold front passes, winds will shift to be out of the northwest and pick up in speed significantly. Sustained winds will likely reach around 55–65km/h, but very strong gusts are possible; it’s highly likely that Winnipeg & the Red River Valley will see wind gusts to 90km/h, however with very strong winds within the conditionally unstable layer and precipitation very likely, it’s possible that wind gusts exceed 100–110km/h. Winds at these speeds can be hazardous when driving and cause damage to buildings (especially roofs) and trees.
NAM forecast sounding for Winnipeg, valid 12Z October 12, 2015
This forecast sounding for Winnipeg from the NAM shows very strong winds near the surface, with up to 60kt present at the top of the low-level instability.
The strongest winds will begin to subside mid-to-late morning, but strong northwesterly winds of 50km/h gusting to 70km/h will likely be in place for the remainder of Monday. The day will start of with a temperature around 9 or 10°C and see it drop to around 4°C by the end of the day. The bulk of the precipitation should taper off with the winds mid-morning, and when all is said and done, this system will likely produce around 5–10mm of rain over the Red River Valley, although for the northern half, there’s a slight chance of seeing more along the lines of 10–15mm.
Environment Canada has issued a wind warning for the Red River Valley regarding this system with the following discussion:
An intense low pressure system will track across central Manitoba tonight and Monday morning. A strong cold front extending southward from this low will sweep across southern Manitoba tonight. Very strong northwest winds will develop in the wake of this cold front with the strongest winds in the Red River Valley as winds will funnel down the valley. Sustained winds of 60 to 70 km/h with gusts over 90 km/h are likely beginning late tonight and lasting until early afternoon on Monday. Winds will gradually subside Monday afternoon from west to east as this system heads off into Ontario.
Damage to buildings, such as to roof shingles and windows, may occur. Loose objects may be tossed by the wind and cause injury or damage. Be prepared to adjust your driving with changing road conditions due to high winds. Avoid wooded areas to prevent injury from falling trees or branches. Campers should move to sturdy shelters.
Be sure to tie up any loose objects and remove fabric canopies from gazeboes. Bring in any objects that could catch the wind, and maybe flip your trampolines over so the wind doesn’t do it for you. It’s going to be a bit of a busy night and a wild Monday morning, so batten down the hatches!
Occlusion is a part of the natural life-cycle of low pressure systems. In simple terms, it means the low has “detached” from the fronts. ↩
This week will feature near seasonal weather for early October. Temperatures will hover in the mid teens.
Monday
Today will feature mainly cloudy skies with temperatures in the mid teens. There will be a chance of showers throughout the day as a strong upper low sits to our west. Precipitation accumulations are not expected to be significant. Winds will be southwesterly at 20km/h.
Tuesday
Tuesday will be mainly sunny with temperatures once again in the mid teens. A surface ridge of high pressure will be responsible for the sunshine. Winds will be breezy from the north-west at 20km/h.
Wednesday
Wednesday will be mainly cloudy with a chance of rain late in the day. An approaching low pressure system may generate an area of rainfall over southern Manitoba later on Wednesday, possibly bringing light to moderate rainfall accumulations to the region. Stay tuned for further details as we get closer to this event.
Long Range
The long range forecast continues to suggest above normal weather for Manitoba over the next few weeks. The current pattern of above-seasonal weather may be partially the result of the El Nino conditions in the Pacific Ocean. As we push further into the fall, it is expected that the El Nino will begin to exert more noticeable effects on our weather.
