The cold weather evidenced by a temperature that dipped down to a very chilly –3.8°C at the Winnipeg Airport on Tuesday morning has quickly been replaced by more seasonal conditions which will persist through the remainder of the week. Sunshine will be a bit harder to find, though, with plenty of cloud and unsettled weather in place as low pressure system stalls out over Southern Manitoba.
Today will start off fairly pleasant with temperatures in the 8–10°C range and partly cloudy skies. The cloud will only increase as the day progresses, however, ahead of an approaching low pressure system. As the low gets closer, winds will strengthen out of the south to 30–40km/h, with some gustiness on top of that, while the temperature climbs towards our daytime high of 17°C.
Scattered showers will develop through the afternoon and become more widespread heading into the evening. There’s a very outside chance of a thunderstorm, but the risk is quite isolated and something along the lines of isolated moderate to heavy showers activity is more likely. Rainfall amounts overnight will vary widely with anywhere from 2–10mm generally expected, however localized patches of more or less are possible. Winds will continue out of the south to southeast at 30–40km/h overnight with a low near 11°C.
One shot in the dark at rainfall totals across Southern Manitoba through the day on Thursday.
Thursday will see the showers gradually taper off through the day as temperatures climb to around 15°C with breezy south-easterlies continuing at 30–40km/h. Skies will remain fairly cloudy through the day and into the overnight hours. Some clearing will work its way into the Red River Valley from the east overnight as temperatures dip to around 7°C.
Friday will finally bring clearing skies and slightly warmer temperatures as the cloud pushes off to our west. Winds will remain fairly breezy at 30–40km/h for much of the day before tapering off towards evening hours. Temperatures will climb into the upper teens for daytime highs through the Red River Valley and dip down to a chilly 5°C or on Friday night.
Pleasant Weekend Ahead
All things considered, this weekend will be quite pleasant. Just a few clouds are expected to be around with daytime highs in the mid-teens & less windy conditions than we’ll have rounding out the work week.
The Red River Valley had an abrupt cool-down Monday evening as a dry, but quite potent, cold front pushed across the Red River Valley, dropping some of the warmest temperatures in the country by 10°C in a matter of an hour and returning the region to far more seasonal temperatures. The foray into fall will be brief, however, as warmer weather is already set to build back into the region over the coming days.
Today will be a bit of a mixed day; skies will be cloudier than not, but fortunately things should remain fairly dry with a high temperature near 17°C. The wind will be noticeable, though, as it builds out of the east through the morning to around 30–40km/h with some gustiness on top of it. The cloud will stick around through the night with an increasing chance of showers overnight.
This forecast sounding for Winnipeg from the 4km NAM shows tremendous vertical velocities on Wednesday morning.
There’s uncertainty to how intense the shower activity will be and whether or not there will be any thunderstorms over the Red River Valley. At this point, the weather model most in favour of thunderstorm development has been the NAM model from the NWS. It’s difficult, though, to fully believe its output given some of the parameters it has been outputting.
Shown above is a forecast sounding from the 4km NAM model for early Wednesday morning. It reveals a high likelihood of thunderstorms, however what’s more important is the omega values it’s producing. Omega (Ω) is a measure of how fast air is moving up or down in the atmosphere, and often has values in the range of ±5–10µb/s. In strong summer-time convective situations, Ω can have values in excess of –60µb/s. The 4km NAM is producing values in excess of –160µb/s, which seems a bit physically implausible. The NAM follows similar ideas, which gives me hesitation to jumping on board the thunderstorm train.
Ultimately, any precipitation over our region is part of a secondary area of lift enhanced by confluence near a deformation zone of a larger system passing to our southeast. Because of that, it seems quite likely that we’ll see some shower activity this evening or overnight with a slight chance of an isolated thunderstorm or two. The more extreme solutions being presented by the NAM seem misplaced given the large-scale dynamics present. There’s always an off chance that the model that seems way out to lunch is correct, but I wouldn’t bet the farm on it at this point.
Thursday will be a bit of a damp day with cloud and scattered showers sticking around for at least the first half of it. Any remaining precipitation will taper off through the afternoon, but the cloud looks like it will stick around through the overnight, sustained by another approaching area of lift. Expect a high in the upper teens on Thursday with an overnight low in the low teens. Fortunately, the winds will be fairly light.
Warming Trend Begins on Friday
Friday will see the heat return to Winnipeg & the Red River Valley as a warmer air continues to push its way into Southern Manitoba. Winds will gradually pick up out of the south to around 30km/h in the afternoon as the temperature climbs into the low 20’s, some 5–8°C above seasonal highs for this time of year. The cloud will gradually push out of the region through the day, likely leaving us with more sun than cloud in the afternoon, making for pleasant fall conditions.
Overnight lows will fall just to the mid-teens on Friday night.
Beautiful Weekend Ahead
This weekend looks positively beautiful for late September. Saturday looks to be a fairly sunny day with highs climbing into the mid- to upper–20’s with winds gradually tapering off. It looks like there will be a chance for some rain or thunderstorms over lake Winnipeg (mainly the South Basin & the Narrows) and areas east through the overnight period as a cold front pushes into the region.
The GDPS is forecasting a surge of warm air pushing into Manitoba on Saturday, shown by this 850mb – about 1.5km off the ground – temperature forecast.
Sunday looks cooler than Saturday with a slight chance of morning showers, but all in all it should still be a pretty nice day. Mixed skies will accompany a high in the low–20’s, still some 5–10°C above normal. Winds don’t look to be too much of an issue either. All in all, for this late in the year, the weather this weekend looks fantastic.
Next week has the potential to be more unsettled, as many models are showing a train of disturbances pushing across the Northern Plains of the U.S. These systems can often bring rainy weather to Southern Manitoba, but at this point it’s far too early to say one way or another how things will go. For now, enjoy the rest of the week and the coming warmth!
After a pleasant, summer-like start to the week, the weather is set to turn more unsettled as a disturbance rolls through Southern Manitoba tonight. Fortunately, the agitated weather will only bring temperatures back towards seasonal values before we see the heat move back in through the weekend, setting Winnipeg & the Red River Valley up for a hot start to next week.
Today will be a fairly pleasant day in the Red River Valley. There’s a slight chance of some shower activity early this morning as a trough passes through the region, but afterwards we’ll see the cloud begin to clear out through the remainder of the morning leading to just a few clouds this afternoon through the region. Daytime highs will climb to around 21°C–but with significantly less humidity than yesterday–with winds initially out of the northwest at 20–30km/h tapering off through the morning.
The more significant weather will roll into the province this evening as a low pressure system lifts northeastwards out of North Dakota and pushes across southern Manitoba. An area of showers, likely with thunderstorms embedded, will develop across southern Saskatchewan and northeastern Montana and spread eastwards through the night, pushing into southwestern Manitoba early in the evening and then spreading into the Red River Valley and Interlake through the remainder of the night. As is typical with systems that involve convection through the night-time hours, model solutions are a little scatter-shot as to what the outcome will be. Overall, it appears that the bulk of the precipitation will pass to the north of Winnipeg, however some models are coming up with solutions that bring significantly more precipitation into the region.
This simulated RADAR image from the NAM forecast valid on Thursday morning shows a band of heavy, convectively-driven rain over Winnipeg & the Red River Valley.
The NAM-based solutions all tend to produce fairly strong, convectively-driven rainfall over the Red River Valley late tonight into Thursday morning. With PWAT[1] values near 35mm, the rainfall could be quite intense, however strong winds aloft should be moving anything that develops along at a fairly decent clip, meaning overall rainfall accumulations shouldn’t be excessive with around 10–20mm in any heavier precipitation that develops. Outside of thunderstorms/heavy rain cells, the more general rainfall amounts from this system should be around 2–5mm or so in regions south of the Trans-Canada Highway, and closer to the 5–10mm range for areas northwards.
This forecast sounding for Winnipeg from the NAM for Thursday morning indicates heavy rain or thunderstorms may be possible.
Temperatures will dip to around 14°C tonight. Thursday will see a high near 15°C with winds increasing out of the northwest to 40 gusting 60km/h in the afternoon. A chance for showers will persist through the remainder of Thursday under mainly cloudy skies.
Friday will bring calmer weather to the region with mainly sunny skies and a high near 19°C. Winds shouldn’t be too bad at around 15–20km/h.
Warmer Weather Returns on the Weekend
Our cool-down to seasonal temperatures will be short-lived, however, as warmer weather is set to build back into Manitoba through the weekend. The upper-level trough that will bring us our unsettled weather will push off to the east and a zonal flow is forecast to quickly develop across the Prairies, pushing in warmer air aloft that will begin to bump our temperatures back upwards. Saturday looks to have a high around 20°C, while Sunday will see the mercury climb towards the mid–20’s.
This forecast of 850mb temperatures from the GDPS shows temperatures pushing into the upper teens on Monday morning.
The GPDS is forecasting 850mb temperatures pushing into the upper teens through Monday, which would equate to temperatures in the upper 20’s as long as we see the sunshine. Afterwards, it looks like we may see a couple more disturbances roll through in the remainder of the week, bringing temperatures back towards seasonal.
While we will have occasional cool-downs, long-range forecasts continue to forecast above-normal temperatures through the remainder of September.
This week will be significantly cooler than last week as we see cooler air filter down from the north. However, temperatures will remain at, or slightly above, seasonal values.
Monday
Today will see temperatures in the low to mid twenties under a mixture of sun and cloud. There may be a few showers throughout the day as we remain behind a departing low pressure system. Winds will be breezy from the south-west.
Tuesday
Tuesday will be a mainly cloudy day with a strong likelihood of showers. Despite the departure of Monday’s low pressure system, a large upper disturbance will remain to our north, helping to generate additional precipitation. Accumulations from these showers isn’t expected to be large, but the chance for more rain is definitely not welcome in most of southern Manitoba.
Shown here by the RDPS 500mb forecast, a large upper-level low will impact much of Manitoba on Tuesday.
Wednesday
Wednesday will see very similar conditions to Tuesday. There will once again be a strong chance of rain, with accumulations perhaps a bit higher than Tuesday. This round of rainfall will be the result of a new system moving up from the northern United States.
Long Range
The long range forecast suggests we’ll generally see near seasonal conditions over the next week, which means high temperatures near 20C. At this point long range models suggest we may turn toward cooler conditions by mid-month, but it’s too early to tell if that will come to fruition.
