Category: Forecasts

Seasonal Long Weekend Ahead

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Seasonal weather will be in place over southern Manitoba as the last long weekend of the summer arrives. Conditions will be fairly dry except for a disturbance rolling through on Saturday night.

Friday
22°C / 8°C
Chance of morning showers, then clearing

Saturday
23°C / 14°C
Mainly sunny; showers or thunderstorms likely overnight

Sunday
23°C / 10°C
Morning showers or thunderstorms then clearing

All in all it’s going to be a lovely weekend with most of the chances for precipitation outside of “plan-ruining” hours. Today we’ll see a chance for some morning showers – or perhaps even an isolated thunderstorm – as a cold front passes through the Red River Valley. Winds will shift to the north behind the front and temperatures will climb to around 22°C under increasingly sunny skies for the afternoon.

Tonight will be clear with a low of around 8°C.

Saturday will be a very pleasant day with mainly sunny skies and a high near 23°C. Winds will shift to southerly through the day, but remain relatively light at 20–30km/h. Some cloud will begin streaming into the Red River Valley ahead of an approaching low pressure system that will move through on Saturday night.

Storm-total precipitation amounts forecast by the GDPS for Saturday nights storm.
Storm-total precipitation amounts forecast by the GDPS for Saturday night’s storm.

This system will be compact and intense with strong dynamics associated with it. Showers and thunderstorms will spread into the Red River Valley overnight on Saturday – likely not until late overnight. It’s unclear if much of a severe threat exists with these storms, although it does look like they could be fairly strong. Rainfall amounts will be dependent on the timing and intensity of convective activity, but in general it looks like 10–20mm of rain is likely, with isolated amounts approaching 50mm possible in worst-case scenarios.

The activity will continue into Sunday morning and clear out by mid-day. The rest of Sunday will be quite nice with clearing skies and temperatures climbing to around 22°C. Sunday night will be mainly clear with temperatures dipping near the 10°C mark.

A Beautiful Holiday Monday

For the upcoming holiday Monday, it looks like another pleasant, seasonal day with highs near 21 or 22°C and mainly sunny skies. The pattern looks to hold for much of the remainder of the week, where conditions look dry and the possibility of some warmer weather returns near week’s end.

Have a great weekend!

Summer Returns

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After an early blast of fall-like weather earlier this week, Winnipeggers will be pleased to hear that summer will quickly return to Southern Manitoba.

Wednesday
24°C / 13°C
Warming up with some afternoon cloud

Thursday
27°C / 15°C
Mainly sunny. Off-chance of a late-day shower

Friday
23°C / 9°C
Morning cloud with gradual clearing

There’s little to say about the weather heading our way the next few days. Today will be a pleasant day with highs near 24°C with some afternoon cloud and winds gradually increasing out of the south to 20–30km/h. Temperatures will dip to around 13°C tonight with partly cloudy skies.

Tomorrow will be a warmer day across the region with highs near 26 or 27°C. A cold front will begin working its way through western Manitoba through the day and push into the Red River Valley overnight. Despite ample surface moisture, stronger mid-level dynamics remain further north in the Interlake, so it’s likely that the front will be relatively unimpressive through the Red River Valley, but there will still be an off-chance of some isolated strong thunderstorms. In general, showers will be much more likely along the front as it pushes eastwards. Temperatures will drop into the mid-teens Thursday night in Winnipeg with a small chance of showers.

Friday will be a cooler day thanks to the cold front that will push through on Thursday. Highs will be limited to the low 20’s and the day will start off with cloud that will then gradually clear throughout the day. The low on Friday night will drop back into the high single-digits.

Fall-Like Weather Blasts Southern Manitoba

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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.

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

Tuesday
19°C / 10°C
Mainly sunny

Wednesday
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 Low Brings Cooler and Unsettled Weather

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A major low pressure system developing in the United States and forecast to lift northwards into the Eastern Prairies through the weekend will bring generally unsettled weather ahead of a more cohesive area of precipitation that will move through on Saturday night.

Friday
22°C / 15°C
Mostly cloudy with a chance of scattered showers

Saturday
19°C / 15°C
Mostly cloudy

Sunday
23°C / 15°C
Rain ending in the morning; sunny breaks with a risk of strong-to-severe thunderstorms thereafter

Perhaps the single most important thing to keep in mind with today’s forecast is the fact that weather models have little consensus on what’s going to happen over the next few days other than the fact that there will be a large low pressure system that will impact an area somewhere between the Rocky Mountains and the Great Lakes.

That being said, it looks like the next several days will bring mixed weather to Winnipeg. Today will see a chance for scattered shower activity as a weak shortwave rolls across the Red River Valley, but nothing nearly as bad as what hit the city last night, where up to 80mm of rain fell in a rapid deluge through portions of the city that resulted in wide-spread flooding through the hardest hit areas.

Temperatures will climb to around 21 or 22°C this afternoon with a light wind out of the north. Tonight will be mainly cloudy with fairly light winds and a low near 15°C.

Saturday: The Low Approaches

Tomorrow will see mainly cloudy skies with a high of just 19 or 20°C. Winds will pick up out of the northeast to 30-40km/h as the main low pressure system for the weekend strengthens and lifts northwards through the Dakotas. By supper time, rain with the chance for embedded thunderstorms will spread through North Dakota into Southern Manitoba, reaching Winnipeg later in the evening.

The RDPS is forecasting an intense convective complex with substantial rainfall amounts on Saturday night. Who knows if it's correct.
The RDPS is forecasting an intense convective complex with substantial rainfall amounts on Saturday night. Who knows if it’s correct.

The rest of Saturday night will be quite rainy with 10-20mm of rain likely across most of Southern Manitoba with localized amounts in excess of 30-40mm due to embedded convection in the precipitation shield. Some models, such as the RDPS pictured above, want to produce upwards of 50-75mm of rain, although at this point that’s likely overdone and a symptom of what’s known as “convective feedback” in the model, something that ends up causing the model to produce too much precipitation when there is widespread convection occurring. Temperatures will drop to around 15°C again with winds out of the northeast at around 30km/h.

More Unsettled Weather on Sunday

The weather on Sunday will likely improve as the low pressure system lifts through the Red River Valley and pushes off to our northeast. Rain will taper off in the morning and Winnipeg will be left under mostly cloudy skies in what’s known as the “dry slot” — the area behind the cold front located between the frontal precipitation and wrap-around precipitation denoted by descending dry air aloft. The high will climb to around 22°C with some strong northeasterly winds becoming light in the afternoon.

Significant instability associated with the low pressure system will be in place, and even with temperatures climbing only into the low 20’s, it will be enough when coupled with the significant moisture in place to present a risk for strong-to-severe thunderstorms. We’ll have more information in the comments on Sunday.

Things will begin to clear out on Sunday night as the temperature drops to around 13°C.

Into next week looks fairly benign with temperatures gradually returning towards normal by week’s end. There will be a couple cool nights in the coming week with overnight lows dipping into the single-digits.

We’ll be keeping an eye on this system as it develops; slight alterations in the track of the system could dramatically impact forecasts, so if any changes are needed we’ll note them below in the comments. All in all it will be a mediocre weekend followed by an improving week.