Another Storm on the Way

Wednesday will be a brief reprieve from the showery weather before a fairly potent low pressure system spreads more rain & thunderstorm activity across Southern Manitoba tonight into tomorrow morning and brings dreary weather for Thursday with strong northwesterly winds.

23°C / 13°C
A few sunny breaks; rain overnight.

19°C / 6°C
Rain and drizzle tapering off mid-day. Risk of a thunderstorm. Windy.

19°C / 5°C
Mainly sunny.

Today will be a fairly pleasant day with mostly cloudy skies and a high near 23°C or so. There’s a slight chance of an isolated shower or three through the Red River Valley, including Winnipeg, but for now it looks like the activity should mainly remain to our west over southern Saskatchewan and southwest Manitoba.

Tonight, an inverted trough extending NW from a low pressure system moving through the Dakotas will spread rain with the risk of thunderstorms eastwards into the Red River Valley. Rain will likely start sometime after 1AM and persist until mid-morning Thursday. The temperature will dip to around 13°C.

The Canadian RDPS is one of the models rather bullish on higher precipitation amounts Wednesday night.
The Canadian RDPS is one of the models rather bullish on higher precipitation amounts Wednesday night.

Rainfall totals for tonight are still uncertain; the general agreement is for between 10–20mm, however if substantial elevated convection develops as much as local amounts of 40–50mm may be possible. The low end of precipitation forecasts produce only around 5mm of rain.

I feel fairly comfortable with 10–20mm of rain tonight, but we’ll reassess the elevated convection potential later today and update if necessary. We’ll try and have an update fairly early this afternoon.

Unpleasant Thursday

Thursday will be quite an unpleasant day as Winnipeg moves onto the back side of the low pressure system lifting northeastwards into Ontario. The bulk of the rain should taper off mid-day, but brisk northwesterly winds building to 30–40km/h will accompany cloudy skies and a high struggling to climb into the upper teens. It’s also fairly likely drizzle will persist after the main area of rain moves out, making for a generally dreary day.

Skies will clear out for the evening, although there may be some cloudy periods through the first half of the night with some cloud moving off of Lake Manitoba, and temperatures will drop to a chilly 5 or 6°C.

Fall-Like Friday

Friday will be fairly pleasant, albeit cool, with mainly sunny skies and a high near 19 or 20°C. Winds will be fairly light through the day.

Friday night should bring clear skies and a low near 5 or 6°C.

A Look Ahead to the Weekend

The upcoming weekend is looking fairly good with unpleasant weather staying to our north. It’s looking like plenty of sun is in store with daytime highs in the ballpark of the seasonal 21°C mark and overnight lows moderating by the end of the weekend.

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.  ↩

Cooler Weather Pushing In

A cold trough pushing into Manitoba will bring showers today and with cold air building over the province, showers may turn to flurries tonight as temperatures drop. The arrival of cooler air will mark a notable regime change which will leave us in a stagnant pattern with slightly below-normal temperatures.


7°C / -2°C
Becoming mainly cloudy; showers in the afternoon.

5°C / -2°C
A mix of sun and cloud; becoming cloudy in the evening.

2°C / -4°C
Mostly cloudy; scattered flurries.

Today will bring increasing cloud this morning which will give way to afternoon showers as a trough slumps through Southern Manitoba. The chance for showers will be very high through Winnipeg & the northern Red River Valley, but through the southern half of the Red River Valley it seems like the showers will be more scattered in nature. Our daytime high of around 7°C will be a couple degrees below our seasonal average of 9°C, and it’s only going to go downhill from there.

Areas that may see lake-effect showers or flurries on Friday night.

Areas that may see lake-effect showers or flurries on Friday night.

We’ll see the showers die off through the evening hours, but it won’t be the end of things; as temperaturs drop in the evening, lake effect showers or flurries will develop in the lee of Lake Winnipeg and Lake Manitoba. Here in Winnipeg it seems like we’ll just see a slight chance of seeing showers or flurries overnight, however to the west and east of the city it looks quite probable.

For the areas that do see precipitation tonight, it may be the first snowfall of the season. While there won’t be much snow and it likely won’t stick, it would not be surprising at all if there were some white flakes falling from the sky tonight. Most areas will see partly cloudy skies tonight save for those underneath the lake-effect cloud and precipitation. Lows will dip to around –2°C with areas under cloud a little bit warmer.

Saturday will be a cool day with a high around 5°C under a mix of sun and cloud. More cloud will push into the Red River Valley late in the afternoon or in the evening as a system diving southwards through Saskatchewan into SW Manitoba spreads some cloud into the Red River Valley. No precipitation is expected at this point for Saturday. Saturday night will be quite cool under partly cloudy skies and lows near –4 or –5°C.

Sunday will bring more cloud into Winnipeg & the Red River Valley as more cool air and instability builds into the Red River Valley. Temperatures will be even cooler than Saturday with highs of only 2–3°C which will make what’s falling out of those clouds more likely to be of the frozen variety than the liquid. Again, not much accumulation is expected, but it may be the first snowfall of the season for many places.

Looking Ahead

We’ll be into a much cooler pattern through the next week with daytime highs sitting near 4 or 5°C through much of the week. It looks like we’ll see a disturbance mid-week bring a chance of showers for most of Southern Manitoba, but nothing in the way of significant (or measurable) accumulations is on the way.

Cooler Weather Settling In

After a windy day yesterday, Southern Manitoba will see cooler weather through the remainder of the week as a fairly seasonal air mass sits anchored over the region. While cool, things will remain dry as any showery weather remains locked up in Central Manitoba & the Northern Interlake.

The Next Few Days


16°C / 3°C
Some cloudy periods.

16°C / 3°C
Partly cloudy.

10°C / 2°C
Increasing cloud, cooler.

Today and tomorrow will be essentially carbon copies of each other. Highs will sit around 16°C with overnight lows near 3°C. Winds are expected to be fairly light both today and tomorrow. Both days will have some cloud around; today we’ll see some cloud pushing up from North Dakota through the Red River Valley while tomorrow we’ll see some cloud slumping southwards from the Interlake. While there may be some light shower activity with the cloud pushing southwards from the Interlake, at this point the entirety of it is expected to remain west of the Red River Valley in the Riding Mountain region slumping southwards into SW Manitoba.

Things will cool off a bit on Friday in the Red River Valley as an intensifying low pressure system in South Dakota/Minnesota draws cooler air from the north into the Red River Valley through the day. Any rain this system produces will remain south of the Canada/U.S. border in the Dakotas and Minnesota. We’ll see some cloud push into the Red River Valley through the day thanks to this system. Exactly who will see cloud and who won’t will be tough to call; the cloud will likely have quite a sharp edge thanks to a strong deformation zone. It will be fairly safe to say that places such as Steinbach and areas SE will end up overcast by day’s end while areas west of Winnipeg, such as Portage la Prairie, will likely remain fairly sunny. Here in Winnipeg we’ll likely sit somewhere near the edge of the edge of the cloud by day’s end.

Looking to the Weekend

The weekend looks fairly quiet over much of Southern Manitoba. Benign weather will dominate over SW Manitoba, things should remain fairly calm over the Red River Valley and the SE portion of the province will see a shot of getting some rain.

An area of rain looks to push northwards out of North Dakota and Northern Minnesota as a developing low lifts NE out of Minnesota on Friday night. The area of rain will have a very sharp edge on it’s northwestern flank thanks to the aforementioned strong deformation zone. Most models are keeping all of the rain in the United States, however some higher-resolution long-range and medium-range models are starting to creep the system a little further west and introduce some rain activity into SE Manitoba on Saturday, likely through the Sprague region. At this point, I’d say that the region has just a slight chance of some rain.

The Red River Valley looks to remain completely clear of the rain for this system with mostly clear skies and cool-to-seasonal temperatures.