Cool Weekend, Warming Next Week

Cool weather will persist across Southern Manitoba this weekend as the region remains under the influence of an unseasonably cold outbreak of Arctic air. Temperatures will continue to slowly moderate, however things will be generally mixed through the weekend with a fair amount of cloud and slight chance of precipitation. The real warm-up will build into the region next week, returning us to summer-like weather.

13°C / 4°C
Mainly sunny

14°C / 5°C
Mainly cloudy

14°C / 5°C
Mixed skies

Today will be the nicest day that the area has seen in a while thanks to a westerly wind which will help dry out the low-levels and clear out the cloud that has been so persistent over the past week. Thanks to that, mainly sunny skies will be seen in Winnipeg and throughout much of the Red River Valley with westerly to southwesterly winds up to around 20km/h. Temperatures will remain cool, however, as the wind will be outflow from the colder air mass slumping to our south; highs through the Red River Valley will sit near the 13°C mark.

Tonight will see mainly clear skies with a little bit of cloud working in from the northwest late in the overnight period and a low near 4°C.

Cool, Mixed Weekend

Saturday will be a mainly cloudy day as a weak trough of low pressure swings through the Red River Valley. While no precipitation looks likely, there will be a slight chance of some isolated, light shower activity. The temperature will climb to around 14°C for a high temperature in the valley.

Skies will begin to clear overnight as the trough slides off into Ontario and winds back to northwesterly, although another slightly cool shot of air will be moving in behind the trough so some cloud with a chance of showers or drizzle in the lee of the lakes is likely. Lows will be near 4 or 5°C in Winnipeg & through the Red River Valley.

Sunday will bring mixed skies with a chance of drizzle or showers in the lee of the lakes. The high will once again be near 14 or 15°C while the overnight low drops to a repeat 5°C.

Warmer Weather Next Week

The NAEFS is forecasting above-normal temperatures across Southern Manitoba in the 8-14 day outlook.
The NAEFS is forecasting above-normal temperatures across Southern Manitoba in the 8–14 day outlook.

Manitobans will be repaid for their patience with the cold weather – if medium-to-long-range enesemble models are to be believed – with a hurried return to summer-like conditions. Both Canadian and American models show an upper-level ridge building eastwards across the Prairies next week brining significantly warmer air with it.

850mb temperatures will climb early next week from the –2°C or so they sit at this morning over Winnipeg to around 10°C. This warming aloft will translate to significantly warmer temperatures down here where we live, with daytime highs moving from low-to-mid teens up to the low 20’s.

The weather also looks fairly dry through the warm-up, although by week’s end there looks to be a chance of showers or thunderstorms as a low pressure complex tracks eastwards through the Prairies & Northern Plains of the United States.

Coldest Weather of the Week Still Ahead

Unfortunately, this week’s plunge into terrible cold for September is far from over, with cooler temperatures still set to work their way into Southern Manitoba. The growing season will be at risk for a tragically early end with frost a slight possibility over the next couple nights here in the Red River Valley.

Calgary, AB and its surrounding areas have been hit particularly hard by this early-Fall oubreak of cold weather, with up to 25cm of snow causing all sorts of problems, including broken tree branches as shown in this picture taken in NW Calgary. Credit: @jpaint (Twitter)
Calgary, AB and its surrounding areas have been hit particularly hard by this early-Fall outbreak of cold weather, with up to 25cm of snow causing all sorts of problems, including broken tree branches as shown in this picture taken in NW Calgary. Credit: @jpaint

The weather story for the Red River Valley over the next few days is dominated by a rather significant high pressure system slumping southwards through Alberta. The 1034mb or stronger high is a result of a large outbreak of cold air from the high Arctic and while the high center is sliding down the foothills of Alberta, the system covers the entire Prairies.

This means that substantially below-normal temperatures[1] accompanied by brisk northerly winds will persist for much of the rest of the week before slightly milder air finally pushes across the Prairies as the high pushes southwards into the United States.

12°C / 2°C
Mixed skies; drizzle possible overnight.

12°C / 1°C
Mixed skies

13°C / 5°C
A few clouds

Today will be a windy day with moderate northerly winds to around 30km/h and a high of only 12°C or so. Skies will be fairly mixed, although it will become more consistently cloudy this evening as cooler air begins working into Southern Manitoba aloft and the lakes begin producing more cloud. By late-evening a slight chance of drizzle will work its way into Winnipeg as north/northeasterly winds bring in cloud streamers off the south basin of Lake Winnipeg. Drizzle or showery weather is more likely near the Portage La Prairie region where Lake Manitoba, under slightly colder air and more favourable wind profiles undergoes more vigorous lake-effect activity.

Temperatures will drop to around 2°C or so, however it’s possible that the temperature drops to the freezing mark with some frost in some of the rural areas in the Red River Valley, depending on where cloud vs. clear skies set up.

Thursday will bring mixed skies again, although the winds should be a bit lighter than today. The high will once again be around 12°C. There will be more cloud from the lakes on Thursday night and a slight chance for some drizzle down-wind of the lakes as we head to a low of around 1°C. Once again, it’s possible some areas see the temperature drop to the freezing mark in rural regions, depending on cloud cover.

Friday will bring a shift in the weather as the high finally slumps to our south and westerly winds work their way in. We won’t see the temperature move much during the day thanks to the fact that, despite the shift in wind, southern Manitoba will still be under the influence of outflow winds from the high. The westerly winds should clear things out, allowing for our sunniest day of the week.

A disturbance will then begin diving southwards from the Northern Prairies on Friday night, spreading cloud ahead of it and slightly milder temperatures aloft. As a result, temperatures will likely be a little warmer on Friday night with lows near 5°C.

Improving Conditions for Next Week

Looking ahead, things look to begin gradually improving on the weekend. Saturday will bring some sun and cloud alongside a slight chance for some shower activity as a weak disturbance trundles through. On the backside of the system lake-effect showers/drizzle will again be possible on Saturday night. Temperatures will likely be limited to the low teens on Saturday.

Sunday will be a nicer day. At this point it looks like it will likely be a mainly sunny day with a high in the mid-teens. There’s some discrepancy in models right now with some models suggesting a mainly cloudy day, others mainly sunny. We’ll have to wait and see what exactly pans out for the day.

The NAEFS 8-14 day temperature anomaly forecast is calling for above-normal temperatures in Southern Manitoba.
The NAEFS 8–14 day temperature anomaly forecast is calling for above-normal temperatures in Southern Manitoba.

Into next week, it looks like we’ll see a return to summer weather as a surge of warm air spills eastwards across the Prairies. The NAEFS[2] is calling for above-normal temperatures in the 8–14 day outlook, which will be a welcome relief after this very early cold snap. Models are suggesting that next week will be relatively dry, with the potential for rainfall near the end of the week.

  1. Normal temperatures for around August 10th in Winnipeg are highs of 19°C and lows of 7°C.  ↩
  2. North American Ensemble Forecast System  ↩

Fall-Like Weather Blasts Southern Manitoba

Southern Manitoba will see its first blast of fall-like weather as gusty northwesterly winds draw cool air southwards over the region. Fortunately, it doesn’t look like the cold weather is here to stay and seasonal temperatures are expected to return by week’s end.

15°C / 7°C
Mainly cloudy; windy and cool with lake-effect showers possible

19°C / 10°C
Mainly sunny

23°C / 15°C
Mainly sunny

Today will be an unwelcome day for late August as abnormally cold air will move into the province behind the low pressure system that brought 20–40mm of rain to Winnipeg & the Red River Valley Saturday night into Sunday morning. Brisk northwesterly winds to around 30–40km/h will usher in this cooler air and will restrain our daytime high to just the mid-teens. Additionally, the abnormally cool air aloft and favourable wind profiles will combine to produce lake-effect showers that will spread southeastwards towards Winnipeg.

Forecast 850mb temperatures for this afternoon show a trough of cold air anchored over Manitoba.
Forecast 850mb temperatures for this afternoon show a trough of cold air anchored over Manitoba.

Given that, occasional showers are likely in Winnipeg although due to the nature of lake-effect precipitation[1] the precise wind direction will determine whether or not the showers find their way into Winnipeg or whether they end up just north or just south of the city.

The clouds will clear out tonight as temperatures drop to around 7°C.

Tuesday and Wednesday will trend towards seasonal weather. Winds will be relatively light both days while the Red River Valley enjoys mainly sunny skies. Temperatures tomorrow will climb into the high teens while highs on Wednesday will reach the low 20’s. Lows on Tuesday night will bottom out around 10°C while Wednesday night sees more seasonal lows in the mid-teens.

Seasonal End to the Week

Looking ahead to the second half of the week, summer weather returns in full swing. Temperatures heading through the end of the week will see daytime highs in the mid–20’s with overnight lows in the mid-teens. The weather looks fairly dry until Friday when a weak cold front pushing across the province brings the chance for some shower or thundershower activity.

  1. Lake-effect precipitation extends in a very narrow band along the direction of the wind.  ↩

Major Cool Down Begins

A significant change in the weather is underway today as Arctic air blasts southwards, pushing out the pleasant, above normal temperatures we’ve had lately and replacing it with cloudy, cool, windy weather. I hope you enjoyed the last few days, because you probably won’t enjoy the next few.

850mb Temperatures from the GFS

850mb temperatures valid this morning from the GFS model. Warm and cold fronts are depicted.

A cold front, tied to a powerful low pressure system moving through central Manitoba, swept across the Red River Valley overnight, ushering out the warmer temperatures aloft that have given us pleasant temperatures the past few days. In it’s wake is a dramatically different pattern than we’ve seen lately.

Upper troughing will dominate the Prairies as a secondary low, currently spinning up over Montana/Wyoming tracks eastwards and pulls more cold air southwards. This will establish us into a much cooler pattern where cooler, Arctic air is entrenched over the region and it’s significantly harder for us to get those nice warm breaks.

Today we’ll see winds begin to pick up out of the north as temperatures climb to only around 13°C. We’ll get cloudier as the day goes on, and by the late afternoon into the evening some showers will push into the southern regions of the Red River Valley. Further north, we’ll see a chance of showers, however it will be more difficult for any organized precipitation to develop over the northern Red River Valley.

As the aforementioned US low tracks through South Dakota, winds will shift to the north-northeast over the RRV, which when combined with the cooler air being dragged southwards, will bring lake-effect showers into the central Red River Valley. Current model solutions hint that Winnipeg may be in the path of these, however, as usual, the exact wind direction will be crucial in determining where the showers will fall. Temperatures will drop to around +3°C tonight.

Thursday will be a cool day, with northerly winds persisting, cloudy skies and a high of only 7 or 8°C. Lake effect showers will persist in the lee of the lakes, and scattered showers will likely be found throughout the entire Red River Valley. Cold air continues to pour southwards and we’ll drop to near 0°C. Precipitation is…complicated for Thursday night. The GEM-GLB & GFS models are forecasting only around 5mm of rain for Thursday evening over SE Manitoba, including the Steinbach region. Other models, such as the NAM, have a much worse forecast. The NAM spins up the low over the states into a very powerful storm system, which taps into some Gulf moisture over the east-central States and lifts it northwest and slams it into a deformation zone oriented north-south over the Red River Valley. In this outcome, 1-2 inches of precipitation is forecast to fall, some as rain, however much of it as snow. Should we believe the NAM, it would result in many communities east of the Red River waking to find over a foot of snow on the ground! Ensemble forecasts suggest that this is an outlier; most solutions favour a quicker track to the low with less precipitation over the Red River Valley. We’ll keep a close eye on this as it develops, but you should be prepared for the potential for poor travelling conditions on Friday.

Things calm down on Friday as this system leaves the region and we’ll be left with cloudy skies and a high around 10°C. Things look to improve a little bit for the weekend (e.g. we may see the sun), but temperatures will remain locked in the high single digits to low teens as cold, arctic air remains entrenched over the region.