Showers and thunderstorms will once again make their return to Winnipeg & the Red River Valley for the next few days…with a catch. Despite the unsettled weather, it might end up actually being fairly pleasant this weekend for the most part!
Today will be a bit of a mixed bag with some cloudy periods and a high near 21°C. Winds will pick out out of the south to around 30km/h or so through the day.
The first of two systems that will be affecting Winnipeg & the Red River Valley today will be a convective complex lifting northeastwards out of North Dakota. It will spread cloud and a chance through southeastern Manitoba, with just a slight chance of some midday showers in Winnipeg.
The second system that will bring a risk of showers or thunderstorms to Winnipeg is a trough of low pressure that will move into our region tonight from Saskatchewan. There still exists quite a bit of uncertainty as to whether or not any precipitation will push into the Red River Valley tonight; in general, confidence is much higher over eastern Saskatchewan and southwestern Manitoba, where a significant threat for severe thunderstorms exists today.
The most likely outcome at this point is that much of the convection heading towards the Red River Valley will either taper off or dive south into North Dakota where a severe convective event called a bow echo seems probable. There is a slight chance that we’ll see some thunderstorm activity in the Red River Valley overnight, but it doesn’t appear that it would be severe.
Saturday looks like a fairly pleasant day with mixed skies about and a high near 22 or 23°C. There will be a chance for showers late in the day into the evening hours, but in general the activity isn’t expected to be very widespread over the Red River Valley. The temperature looks to drop into the low teens on Saturday night.
The threat for thunderstorms returns to the Red River Valley on Sunday afternoon as another disturbance moves through the region. Temperatures will once again top out in the low 20’s with overnight lows dropping into the low teens.
Father’s Day Forecast Update
Weather will be generally pleasant for Southern Manitoba this Father’s Day with generally sunny skies and high temperatures in the mid-20’s with fairly light winds. This is excellent news for the Manitoba Marathon; today will be a far nicer day to run than last year’s less than pleasant weather. The only exception will be in areas along a line from Swan River east-southeastwards across the Interlake towards Berens River where some pop-up showers and thunderstorms are possible this afternoon.
An more organized thunderstorm threat will develop through the day, however, beginning early-to-mid-afternoon in Saskatchewan and then progressing eastwards through southwest Manitoba this evening and through the Red River Valley overnight. Thunderstorms are expected to develop in the Regina area southwards towards the American border; these storms will be developing in an area with marginal energetics, however very favourable shear profiles will likely result in scattered thunderstorms with isolated supercell thunderstorms. As they track eastwards, a southerly low-level jet will intensify, supporting upscale growth of the convective complex as it heads into the evening.
I expect that early in the evening, the thunderstorms will have developed into a line of showers and thunderstorms heading eastwards into Southern Manitoba. In general, the severe threat in Manitoba is expected to be minimal, except for areas near the U.S. border. There is a chance that as the storms push eastwards, supported by a 50-60kt westerly jet at 500mb and running just north of a warm front in North Dakota, that the storms develop bowing segments. Bowing segments are when the thunderstorms produce strong winds that, quite literally, push part of the storm forward, making a ) shape on RADAR imagery.
Primarily for that reason, I’ve carried a slight risk for the overnight period along the US border into the Red River Valley; I’m generally expecting the worst weather to dive into North Dakota fairly early, but there’s a slight chance some of the winds end up remaining on the Manitoba side. For the remainder of the general area through southwest Manitoba into the Red River Valley, non-severe nocturnal thunderstorms are possible through the evening/overnight period.
Brad, maybe you can shed some light on this. For the last few years it seems as though SW MB has been the focal point for storms lately, where as Winnipeg and the red river valley have missed out so much over the last few years. This has also been giving abundant precipitation to SW MB, which is normally drier then the RRV (even considered semi arid on one article I read). Why has this been the case? What synoptic pattern do we keep getting into that has favored this situation?
You’re bang on with that observation; southwest Manitoba has indeed been getting much of the thunderstorm-related activity over the past several years. It’s very difficult to pin down any one particular reason. As a generality, the jet stream has been a bit further south during much of the summer the past few years, and with the dynamics supportive of thunderstorms a bit further south, it could explain why so many storms become significant when they cross south of the Canadian border.
Overall, though, I don’t think it’s a vastly different synoptic pattern that’s causing it; rather, it seems more like a lot of the activity has simply shifted to the southwest a bit. Rather than a different synoptic pattern, perhaps the location is just shifting?
Unfortunately, I don’t think I have a satisfactory answer for you! Your observation is certainly correct, but the why is a bit of a mystery!