A Weather Moment

Warm and humid weather will bring a chance of showers or thunderstorms to the Winnipeg area this weekend.

An upper ridge will continue to build over the eastern Prairies to end the week, bringing warmer temperatures and a shift into one of the first humid periods of the year. Dew point values will climb from the low and mid-teens into the upper teens or even the low 20s over the next 24 to 48 hours. This will shift conditions to be notably more humid than seen for any notable period this season.

This push of warmer and humid weather will turn unsettled as an upper trough begins to deepen over western North America. This will send multiple disturbances towards the region over the next few days, each bringing a chance of showers or thunderstorms with them as they track through.

There will be a chance of showers thunderstorms this evening, roughly from the northern Red River Valley northeast, along a warm front pushing north through the region.

This frontal boundary will lie draped across the region on Saturday and generate more showers and thunderstorms as potent low pressure system in Alberta begins to shift east. Much of this activity will develop west and north of the Red River Valley, likely leaving Winnipeg dry.

On Sunday, a well-organized low will track through the American Plains and draw the front over southern Manitoba to the southeast through the day. This system will produce widespread showers and thunderstorms across southern Manitoba through the day that gradually taper off on Sunday night.

Temperatures will climb into the upper 20s both today and tomorrow, with the humidity making it feel closer to the low to mid-30s once it pushes in. Overnight lows both nights should sit in the upper teens or low 20s. The cloud and showers on Sunday will keep highs cooler, likely in the low 20s. As the front sweeps southeast later Sunday, a cooler and drier air mass will move into the region. Temperatures will be much cooler on Sunday night, dropping into the low teens.

Lastly, the region could see smoke this weekend from the Nopiming Provincial Park wildfire and from a few other fires burning further into Ontario. Northeast winds developing tonight and through Saturday will draw smoke southwest from these fires, but where the plumes go will be sensitive to the exact wind directions. Best chance to see smoke right now will be east of Lake Winnipeg into the southern Interlake, but there is a chance that the plumes will reach the Winnipeg area. The chance will begin to decrease Saturday night into Sunday, then come to an end as winds swing around with the cold frontal passage later Sunday.

Long Range Outlook

After a cool Monday, temperatures will rebound to seasonal to slightly above-seasonal values through the rest of next week. The region should see variable cloudiness with a chance of isolated to scattered thunderstorm activity on several days.

A low pressure system tracking through the central Prairies may bring hot and humid conditions to the region again next weekend.

Today’s seasonal daytime high in Winnipeg is 24 °C while the seasonal overnight low is 11 °C.

An upper low over the northern Prairies will bring relief from the heat along with unsettled conditions, but smoke will continue to be an issue.

Over the past few days, the upper ridge over the Prairies has been replaced with an upper low anchored near the Hudson Bay coast. Its influence will linger over Manitoba for much of the week as it gradually trundles into Hudson Bay.

For Winnipeg, this means daytime highs will sit in the 20 to 25 °C range for much of the week with mixed skies developing most days. Overnight lows should sit within a few degrees either side of 10 °C.

There will be a few chances for showers or thunderstorms across the region over the coming days. The best chance for much of the region will be this afternoon. Scattered showers and thunderstorms will develop over central Manitoba midday then spread south through the afternoon. With up to 500 J/kg of MLCAPE (instability) and 20 to 30 knots of bulk shear (organization), many of these showers will be capable of developing into thunderstorms. No organized severe weather threat is expected from the activity this afternoon.

The showers will taper off through the evening and skies will clear.

More showers or thunderstorms will be possible Tuesday, but they won’t likely be in Winnipeg. The best chance will be through the Interlake east towards the Ontario border with a slight chance of a few in southeast Manitoba.

On Thursday, a few showers or thunderstorms will be possible from central Saskatchewan southeast into Parkland Manitoba. Another area will develop in the afternoon through the northern United States; a few may track along the border regions but aren’t expected to push further north at this time.

All that said, it means that though there will be a chance of showers or thunderstorms almost every day ahead in southern Manitoba, today will be the only day they’re likely to happen in Winnipeg.

Air Quality an Ongoing Concern

Over the next few days, west to northwest winds will dominate; light winds at night will strengthen into the 20 to 30 km/h range during the day with gusts of 40 to 50 km/h. These winds will draw plumes of wildfire smoke into the region.

The simpler part of the smoke forecast is much of central Manitoba, the Parkland, Interlake, and areas east to the Ontario border will be smothered in smoke for much of the week. Expect very poor air quality through much of the week ahead.

For areas further south, plumes of smoke will either graze by or move through over the coming days. The first push of smoke will move into the region later today with a plume grazing Winnipeg and the northern Red River Valley on its way into the southeast corner of the province. The smoke will clear tonight, then another plume is forecast to slump into much of southern Manitoba on Wednesday morning, then gradually clear from west to east through the afternoon.

Smoke forecasts don’t extend past this point, but it looks like another plume of smoke may impact the Winnipeg area on Thursday. Keep in mind that smoke spread is difficult to forecast, and it’s likely that the details and timing may shift in the days ahead. Keep an eye out for air quality advisories from the MSC in the coming days.

Long Range Outlook

Warmer weather will push into the region to end the week, likely bringing daytime highs into the 25 to 30 °C range. Nocturnal showers or thunderstorms may be possible overnight Friday into Saturday, then widespread showers or thunderstorms will be possible later Saturday into Sunday as a cold front moves through the region.

It’s likely that smoke conditions will improve with the push of warmer air, but more smoke is likely behind the cold front on Sunday.

One of the main things to note is that for the foreseeable future, any northwest, north, or east-northeast wind may bring wildfire smoke into the region.

Today’s seasonal daytime high in Winnipeg is 22 °C while the seasonal overnight low is 9 °C.