Hot and Unsettled Weather Continues

Hot and muggy weather will stick around in Winnipeg for a few more days along with more chances for thunderstorms. Some relief is on the way for the end of the week, though, with more seasonal conditions arriving on Friday.

A hot and humid air mass will remain in place over southern Manitoba on Tuesday.

An upper high entrenched over the eastern Prairies means little change is on the way for Winnipeg over the next few days. That said, there is a change on the way. A developing low pressure system over the southern Arctic is beginning to push cooler air into the northern Prairies. As it matures in the coming days, that cooler air will continue to slump southwards through the Prairies. By Friday, this cold front will sweep through southern Manitoba, clearing out the humidity and lowering temperatures back towards more seasonal values.

Before we get to that, though, there will be a few more days of hot and unsettled conditions in the Winnipeg area. The daytime high will reach the low 30s again today, then ease into the upper 20s for the next couple days. That humid air mass will keep overnight lows mild with lows in the 18 to 20 °C range.

Each of the next few days will also continue to bring a risk of thunderstorms across the region. Here in the Red River Valley, scattered thunderstorms are possible today, but not likely until closer to the evening. Much of the activity will stay west of the region on Wednesday, but an isolated thunderstorm is possible. On Thursday, a chance of thunderstorms will develop across the region later in the day as a cold front pushes through.

With the heat and humidity in the region, there will be a risk of severe thunderstorms over the region. That being said, most will likely be non-severe. Any that manage to organize to severe limits will mainly pose a torrential rain and hail threat.

Long Range Outlook

A break from the heat and humidity will stick around for the weekend, a welcome relief for many. Daytime highs will vary from the low to mid-20s this weekend, feeling very comfortable thanks to lower humidity levels. That drier air mass will also allow overnight lows to cool off into the low to mid-teens.

Warmer weather is expected to return next week with daytime highs climbing back into the 30s.

Today’s seasonal daytime high in Winnipeg is 23 °C while the seasonal overnight low is 9 °C.

Warm With Increasing Humidity This Week in Winnipeg

After the scorching heat last week in the Winnipeg region, it might seem like this week will be cooler with highs of only the upper 20s. That slight cooling will be offset by more humidity in the region, with humidity levels possibly reaching downright muggy levels by Friday.

GDPS 2m Dew Point Temperature Forecast valid 00Z June 3, 2023
A extended southerly flow will bring a more humid air mass from the Gulf of Mexico northwards to southern Manitoba by the week’s end.

It will be another unsettled day in the Winnipeg area thanks to a shortwave lifting across the region from the Dakotas. As it moves into the warm and relatively humid air mass in our region, scattered showers and thunderstorms will once again develop. These will persist through the afternoon and into the evening before tapering off.  The city will see a high in the mid-20s give way to an overnight low in the mid-teens.

Heading into mid-week, an upper ridge will begin to build over Central Canada. It will bring warmer temperatures to the region while also supporting a deep southerly flow from the Gulf of Mexico northwards through the American Plains. Daytime highs will rise into the upper 20s, but at the same time, an increasingly muggy air mass will build northwards. Dew point temperatures will increase from around the mid-teens to close to 20 °C by Friday. This will make for very muggy conditions to end the week that will make the highs in the upper 20s feel more like the mid-30s.

Along with the heat and humidity will come some unsettled conditions as well. Isolated to scattered [thunder]showers may be possible as the week progresses.

Long Range Outlook

Very warm conditions will return for the weekend with daytime highs likely climbing into the low 30s. If the humidity remains high, then it would almost certainly result in another heat warning for Winnipeg and the Red River Valley. Again, though, it won’t be completely stable and some showers or thunderstorms will be possible through the weekend.

More settled conditions will return next week as the humidity begins to leave the region. With a drier air mass, highs will hover in the upper 20s with overnight lows in the mid-teens through the first half of next week.

Today’s seasonal daytime high in Winnipeg is 22 °C while the seasonal overnight low is 8 °C.

Summer Warmth Arrives in Winnipeg This Week

After a bit of an unsettled Tuesday, sunnier skies develop over southern Manitoba with high temperatures climbing into the mid-20s!

RDPS 2m Temperature Forecast valid 21Z Thursday May 11, 2023
Temperatures will climb into the mid-20s across southern Manitoba on Thursday.

Warmer weather will arrive in Winnipeg today with daytime highs climbing back to around 20 °C. A weakening upper trough over the region will provide instability for mixed skies with some scattered afternoon showers. The odd shower might end up strong enough for a couple lightning strikes, but no notable organized thunderstorm activity is likely. A few clouds will linger overnight with temperatures heading down into the low teens.

The weather over the next few days will be shaped a building upper ridge over the eastern Prairies. This will settle conditions and push warmer weather northwards. With sunny skies on Wednesday and a bit of cloud on Thursday, temperatures will climb into the mid-20s. In addition to the warmth, dew point values will hover close to 10 °C, making for very comfortable conditions.

Overnight lows will continue to dip into the 10–15 °C range at night. On Wednesday night, there will be a small chance of some showers driven by some weak instability aloft that will persist through the night.

Long Range Outlook

Cloudier conditions will move in for Friday and Saturday in southern Manitoba. A potent low pressure system will spread rain into the northern United States, but a strong deformation zone will keep a sharp cut-off to the rain south of the Canada–U.S. border. The cloud will combine with moderate northeasterly winds to send daytime highs a few degrees cooler; Winnipeg will see daytime highs near 20 °C to wrap up the week.

Sunshine will return ton Sunday as this storm system clears. Temperatures will head back into the mid-20s with the heat persisting into next week.

Today’s seasonal daytime high in Winnipeg is 18 °C while the seasonal overnight low is 4 °C.

Weekend Brings Start to Spring Melt

A strong upper ridge will spread a much warmer air mass into the eastern Prairies this weekend, marking the start of a widespread spring melt.

GOES-16 True Colour RGB Image of the Southern Prairies valid 0019Z Friday April 7, 2023
True-colour satellite imagery from Thursday evening reveals a widespread snowpack (white) across much of southern Saskatchewan, southern Manitoba, and North Dakota.

As we mentioned on Tuesday, southern Manitoba will see a much warmer air mass move into the region this weekend as upper ridging persists over western Canada. While this feature will produce plenty of warm air that will head east, the biggest wrinkle in the whole thing is the extensive snow pack across southern Manitoba and North Dakota.

This deep layer of snow will keep the surface cooler and help support an inversion across the region. An inversion is when temperature warms as you go up instead of cooling. This can effectively limit the ability for the warmer air over top of the surface to reach down to the ground.

Mild air will certainly stream into the province this weekend. Temperatures at 850 mb — about 1.5 km above the ground — will climb from around 0 °C on Saturday to warmer than 15 °C on Tuesday into Wednesday. Now, if we had full sunshine and dry, bare ground, that could result in daytime highs climbing from the low teens into the upper 20s. But the snow will absolutely keep temperatures much cooler than that.

850mb temperature anomalies — how much warmer or colder than the seasonal average values — show the entire Prairies seeing a seasonably mild air mass by the end of the weekend (left image). Heading into next week, though, the air mass becomes unseasonably warm over the southeastern Prairies (right image). How this abnormal warmth will interact with the existing snowpack is unclear at this time.

The other factor to pay attention to that will dramatically impact how quickly the snow melts will be the dew point temperature. When the dew point is below freezing, it is easy for water that is draining through the snowpack to re-freeze within it. But when the dew point climbs above freezing, that process becomes much harder and the rate the snow pack will melt at increases. The dew point will likely climb to the positive side of freezing this weekend, then increase several degrees above freezing next week as the warmer air pushes into the region.

The last factor to take into account is what all this water that’s melting out of the snow will do. With warming temperatures aloft and a strong inversion, that moisture will be trapped near the surface. This could result in the development of fog and low clouds as the melt picks up, which would also work to reduce potential high temperatures and produce cloudier conditions that really lock temperatures fairly close to freezing. It’s simply impossible to tell at this time if that will happen this weekend, but it’s a possibility to keep in mind.

So all that said, what can we expect?

After a cold start to the morning, temperatures will climb to a high near freezing this afternoon with a light southerly wind. Temperatures will dip back down into the minus teens tonight, the the warmer air mass begins building in this weekend.

Temperatures will climb to a high a few degrees above freezing on Saturday and Sunday with light southerly winds continuing. Overnight lows will be much warmer, just dipping below freezing overnight on both nights. Conditions will likely be sunny, but particularly beginning Saturday night there may be a chance of seeing widespread fog or low cloud develop. If it does, it could persist through Sunday and into the start of next week.

The snowpack will likely begin to melt at a faster rate as dew point values climb above freezing on the weekend.

Long Range Outlook

Next week will start off with a very warm air mass moving over the region, with the large question mark of how the near-surface layer will interact with the snowpack. Continued southerly winds will likely serve to reinforce the low-level inversion, but the sheer magnitude of the warm air will likely result in either (a) temperatures climbing towards 10 °C or even warmer in any areas with an eroded snow pack, or (b) widespread development of low cloud that results in near-surface temperatures again only a few degrees above freezing.

It’s simply too early to know exactly how that will go at this point, but we’ll be keeping an eye on things through the weekend.

One thing for sure is that substantial amounts of snow will melt next week, both in southern Manitoba as well as North Dakota. The water may appear relatively quickly, so we encourage anybody in areas that may need to be concerned about flooding to keep a close eye on updated flood conditions and forecasts. Moderate to major flooding is possible along parts of the Red River in North Dakota and Manitoba. Depending on the rate of snowpack melt in Manitoba, overland flooding may also be an issue beginning next week.

Fortunately, there is little risk for any notable precipitation across southern Manitoba over the coming week.

Today’s seasonal daytime high in Winnipeg is 7 °C while the seasonal overnight low is -4 °C.