Wednesday Brings Showers and Thunderstorms to the Red River Valley

Southern Manitoba will see showers and thunderstorms today as a low pressure system moves into the province.

Winnipeg will see increasing cloud today as a low pressure system pushes a warm front into the province. The initial batch of showers with isolated thunderstorms will spread eastwards along a warm front into the Interlake this morning. This area of rain will likely will stay north of the Trans-Canada Highway, but there will be a small chance of scattered (thunder)showers further south through the day. With all the cloud cover over the region, highs will be seasonal despite the push of warmer air. Winnipeg should see a high near 18°C with breezy southerlies near 30 gusting 50 km/h.

The thunderstorm threat will increase this evening as a cold front begins working its way across southern Manitoba. This may end up being one of the first organized severe weather threats of the season for southern Manitoba. Going over the MIST ingredients:

  • Moisture: A southerly fetch ahead of the warm-sector trough will draw moisture northwards. Dew points will rise into the low teens along a narrow strip ahead of the trough.
  • Instability: Marginal mid-level lapes rates will limit instability despite the surge of low-level moisture. MLCAPE values will likely climb into the 500 to 1000 J/kg range by the end of the day.
  • Shear: A 60 kt jet overriding the frontal boundary will produce 50 to 65 kt of 0-6km bulk shear. While high, it’s not unreasonable for thunderstorm development.
  • Trigger: Convection will focus along a cold front as it destabilizes the low-level inversion inhibiting surface-based convection.
Most forecast models show a line of thunderstorms moving through the Red River Valley this evening as the cold front pushes through.

All in all, it looks like there’s a good chance of marginally severe thunderstorms developing on Wednesday evening. Strong shear will support the development of multicellular thunderstorms that may grow upscale along the front into a line of showers and thunderstorms as the evening progresses. These thunderstorms will initiate near the Saskatchewan border and then progress east-southeast across the Red River Valley through the evening. Some of these thunderstorms may become severe with primary threats being large hail and/or damaging wind gusts. The convection will clear out in the evening with breezy northwest winds of 30 gusting 50 km/h picking up behind the cold front. Temperatures will dip to a low near 7°C.

Thursday and Friday will bring variable cloudiness as a developing storm system slowly intensifies. A ridge of high pressure extending from Nunavut southwards through the province will keep things seasonably cool and dry. Tonight’s northwesterly winds will slowly taper off through the day on Thursday, with light winds expected on Friday.

Long Range Outlook

More cloud is on the way for the weekend with temperatures remaining in the mid-teens. Forecast models diverge on Sunday with American models suggesting a broad area of rain lifting northwards into southern Manitoba while the Canadian models keep things further south. With the strength of the ridging over Manitoba, I’m inclined to side with the Canadian models at this point, but we’ll certainly be keeping an eye on things to see how they develop.

Today’s seasonal daytime high in Winnipeg is 20°C while the seasonal overnight low is 5°C.

Warm And Unsettled Conditions Ahead

Several disturbances tracking across the southern Prairies will bring warm temperatures, variable cloudiness, and several chances for showers or thunderstorms.

Winnipeg will start the day with cloudy skies, but skies will clear a bit later this morning. After that, a truly summer-like day lies ahead as temperatures climb to a high near 24°C with light southerly winds. The city will see a chance of showers or thunderstorms late in the day as a cold front moves through. Skies will clear for the first half of the night as temperatures head to a low near 10°C. A low in Saskatchewan will spread cloud back into the region through the second half of the night, though.

Tuesday morning will kick off with a good chance of showers with a small chance of thunderstorms as a disturbance rolls through. After it moves through, skies should clear out fairly quickly leaving much of the day with sunny skies. Daytime highs will be cooler than today, but still pleasant at a seasonal 19°C with light winds. Temperatures will dip to a low near 6°C on Tuesday night under clear skies.

Showers with the risk of thunderstorms will move though the Red River Valley early Tuesday morning.

On Wednesday, Winnipeg will see increasing cloudiness as a low pressure system approaches from Saskatchewan. Southerly winds will strengthen to around 30 gusting 50 km/h, drawing mild air northwards. How warm it gets in the city will largely depend on how long the sun manages to shine. Around 21°C looks most likely, but if skies cloud up earlier in the day, temperatures may end up a bit cooler than that. Scattered showers and thunderstorms will develop on Wednesday evening as the low pressure system moves through. That activity will move out overnight with temperatures dropping to a low near 9°C with light winds.

Long Range Outlook

Looking ahead, it appears that southern Manitoba will be entering a rather unsettled period as a large-scale upper pattern shift occurs. The city will see numerous chances for showers or thunderstorms through the latter half of the week and the weekend. By next week, depending on how things develop, Winnipeg may see itself launch into summer with humid conditions pushing northwards into the region. While there’s some uncertainty depending on how things evolve through the weekend, it does appear that things are finally shifting gears and heading towards summer!

Today’s seasonal daytime high in Winnipeg is 19°C while the seasonal overnight low is 5°C.

Cloudy Skies, Seasonal Temperatures, More Thunderstorms?

Plenty more cloud cover lies ahead for Winnipeg this weekend as another warm front lifts northwards into the province and brings another round of showers and thunderstorms.

Winnipeg will see a bit of sunshine today with some breaks in the clouds expected throughout the day. Daytime highs will climb to a near-seasonal 19°C with light winds courtesy a ridge of high pressure moving through. Winnipeg will see a chance of showers later today as a weak upper-level disturbance rolls through. Temperatures will dip to a low near 8°C tonight with mixed skies continuing through the night.

On Saturday, a low pressure system over North Dakota will slowly lift a warm front north into the province. While Winnipeg may see a bit of sunshine in the morning, skies will cloud over through the day. Winds will be out of the northeast at 10 to 20 km/h. The cooler northeast winds will keep highs near-seasonal despite the advancing warm air.

Thunderstorm Threat Returns to Southern Manitoba Saturday Night

On Saturday night, a low pressure system will begin its trek from southwestern North Dakota towards Lake of the Woods. As it lifts northeastwards, elevated convection will once again fire north of the warm front, spreading showers and thunderstorms through a portion of southern Manitoba. This instability will persist into Sunday with the potential for showers and thunderstorms continuing through much of the day.

Given elevated convection 36+ hours out, there’s still a lot of the details that remain unclear. Early indications are that another round of severe thunderstorms will be possible; guidance suggests a fair amount of instability and strong shear to help the elevated convection organize. Right now it looks most likely over the southern Red River Valley into southeastern Manitoba. It’s early, though, and that could easily shift over the coming days. We’ll be keeping an eye on it. Given the extensive cloud cover and proximity of the warm front, Saturday night will remain mild with a low near 14°C in Winnipeg.

Forecast MUCAPE values reveal the substantial instability forecast to develop over southern Mantioba as a warm front lifts north on Saturday night.
Forecast MUCAPE values reveal the substantial instability forecast to develop over southern Mantioba as a warm front lifts north on Saturday night.

The instability continues through Sunday with a chance of showers or thunderstorms for Winnipeg. It won’t be an all-out rainy day and most of the precipitation should end up north of the city. Winds will be out of the northeast at 15-20 km/h for much of the day. As the low passes in the afternoon, winds will shift northerly to 30 gusting 50 km/h. Temperatures should reach a high near 18°C, but much warmer temperatures will be in place just to the southeast on the other side of the warm front where highs near 30°C are possible, so areas closer to the US border, particularly southeast of Winnipeg, will see much warmer highs. Given the large change in temperatures across the front, if its position ends up a bit further north then Winnipeg could see a much warmer high.1

While Winnipeg will see near-seasonal temperatures on Sunday, it may end up being a scorcher over southeastern Manitoba.
While Winnipeg will see near-seasonal temperatures on Sunday, it may end up being a scorcher over southeastern Manitoba.

The cloud cover will remain as the precipitation moves off to the east on Sunday night. Temperatures will dip to a low near 9°C as cooler air pushes south behind the low.

Long Range Outlook

Monday will bring more cloud to Winnipeg with a slight chance of showers as a weak low pressure system moves through the region. Temperatures will be much cooler with a high in the low to mid-teens. The remainder of the week will bring mixed to cloudy skies and seasonal to slightly below-seasonal temperatures. Another batch of rain looks possible in the second half of the week. After a dry first two thirds of the year, it seems like Winnipeg may finally be beginning to catch up on its precipitation deficit!

Winnipeg’s seasonal daytime high is currently 18°C while the seasonal overnight low is 6°C.

  1. That said, it’s not particularly common for warm air to push further north than expected at this time of year.

Showers and Thunderstorms Move Into Southern Manitoba Wednesday Evening

A low pressure system over the American Plains will bring widespread showers and thunderstorms to southern Manitoba tonight.

More unsettled weather is on tap for southern Manitoba tonight as a warm front lifts northwards through the Northern Plains. Under increasing or mostly cloudy skies today, the Red River Valley will see temperatures climb to a high near 18°C. Winds will persist out of the northeast near 15-20 km/h.

The main event will begin this evening and persist through the night. As the warm front approaches the province this afternoon, showers will blossom over the Red River Valley and southeastern Manitoba. As the night progresses, the activity will organize along a southwest-northeast line parallel to the warm front, gradually shifting eastwards. Most areas in the Red River Valley will likely see showers and/or thunderstorms through the night. Given the convective nature of the rain, accumulations may be highly variable, but most1 areas should see 10-20 mm with the potential for over 40 mm in areas where thunderstorms linger for longer. Some gusty winds are possible in thunderstorms but will otherwise remain in the 10-20 km/h range. Temperatures will dip to a low near 14°C this evening then slowly rise to around 16°C on Thursday morning.

Forecast models have generally good agreement with the convective activity tonight, but amounts will likely be more variable than represented here.
Forecast models have generally good agreement with the convective activity tonight, but amounts will likely be more variable than represented here.

As this system departs on Thursday, it will leave behind abundant cloud cover with winds shifting out of the northwest at 15 to 25 km/h. Winnipeg may see a bit of light rain or drizzle in the morning, but things should dry out for the afternoon. Temperatures will be near-seasonal with a high near 19°C in Winnipeg. There’s a slight chance of some more showers or thunderstorms on Thursday afternoon and evening, but it will likely to remain in southeastern Manitoba and the southern Red River Valley. Skies will remain mostly cloudy on Thursday night with a low near 9°C.

Friday will bring a bit of sunshine as skies become mixed in the afternoon. Temperatures will be a tad warmer with a high near 21°C. Wind will remain light, making for a pleasant afternoon. Temperatures will dip to a low near 9°C on Friday night with mixed skies.

Long Range Outlook

Looking ahead to the weekend, another low pressure system is forecast to develop over the northern Plains. This system will will spread more cloud cover into to the region alongside a couple more chances for showers or thunderstorms.

Winnipeg’s seasonal daytime high is currently 19°C while the seasonal overnight low is 6°C.

  1. Again, given the variable nature of the precipitation, some areas may see nothing while nearby areas receive heavy rainfall.