Category: Forecasts

Mild Second Half of Week; Major Winter Storm Threatens Christmas

Brad 1 Comment

Temperatures will remain above-normal through the second half of the week in what has been an extremely abrupt transition from 10 days of below-normal temperatures when the temperature soared 29°C from a low of -30.5°C on Sunday morning to a high of -1.5°C on Monday afternoon. Other than some brief snow early today, the remainder of the work week will be quite pleasant with a fair amount of sunshine on tap. Christmas, however, may end up being notably worse with a second major snowstorm for December possible.

This morning will bring some light snow to Winnipeg as a shortwave rolls through the Red River Valley. The snow should taper off by mid-morning with accumulations anywhere from 1-2 cm along the Trans-Canada Highway up to 5-6 cm near the U.S. border. As the snow moves out, the cloud will break up and we’ll head into a fairly sunny afternoon with a high near -7°C. Winds will become westerly behind the low to around 20-30 km/h with some gusts on top of that. Expect the winds to continue overnight as skies remain mainly clear and temperatures drop just a couple degrees to a low near -9°C.

Thursday will be a beautiful December day with just a few clouds around and a high near -2°C. Winds will continue at 20-30 km/h, however they will be more southwesterly than westerly. Winnipeg will see a bit of overnight cloud as temperatures dip to a low near -8°C.

Winds will continue out of the west to southwest on Friday as temperatures climb to a high near -5°C under partly cloudy to mixed skies. Skies will be mixed to cloudy on Friday night with a low near -14°C.

Christmas Blizzard Possible

Long-range models have been very consistent in producing a very potent winter storm over Southern Manitoba, the Dakotas, and Minnesota beginning overnight on Christmas Eve and continuing through Christmas Day and into Boxing Day.

There is still significant uncertainty in areas that will be impacted by this storm. The only confidence at this point is that a major winter storm will likely occur somewhere in Central North America on Christmas.

While the location of the system differs between models, a common theme is that all are forecasting 20-50 cm of snow in the worst-hit areas of the storm.

Shown here are the Canadian (GDPS) and American (GFS) long-range forecasts for snowfall accumulated in a 24 hour period between 6AM Christmas Day and 6AM on Boxing Day. Both systems have a core of heavy snowfall greater than 30 cm, however where that occurs is in different places and across varying swath widths.

In general, I’m more partial to the GDPS solution as it creates a sharp deformation zone along the northern track of this system (which tends to happen) and concentrates the heaviest snow through a smaller corridor. Both these features are more physically realistic. That does not mean that I think the GDPS is right, though. Just that it seems to have a slightly more realistic handle on this system. Should the GDPS solution come to fruition, the biggest challenge would be where exactly that northern edge of the precipitation sets up.

While it’s too early to suggest any concrete plans, it would be prudent to have a “Plan B” ready if your Christmas involves travel. The heavy snow will be accompanied by strong northerly winds, likely producing widespread blizzard conditions. In areas hit by this storm, highway travel will likely be nearly impossible and air travel will likely be heavily delayed or cancelled. It seems fairly likely that travel through North Dakota and Northern Minnesota will be hazardous to impossible on Christmas Day. If you are scheduled to travel on Christmas day, it may be prudent to bump your travel day up to the 24th instead of the 25th, particularly if you’re travelling to the United States. Travel conditions will likely improve in the second half of the day on Boxing day.

If this storm materializes, it would be just 19 days after the worst winter storm in nearly a decade dumped 25-40 cm of snow across the region. Having two snow storms that produce over 20 cm of snow in a single month is rare; the last time there were two events of that magnitude was December of 1909, when the first 7 days of the month produced 70.9 cm with snowfalls between 5-19 cm each day.

We’ll be watching this storm as it develops and have a full weekend forecast on Friday.

Winnipeg’s seasonal daytime high is currently -11°C while the seasonal overnight low is -21°C.

A Much Needed Warm-Up is Finally Here!

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A much-needed break from the past week of frigid arctic air has finally arrived. As you read this post, much warmer Pacific air is flooding across southern Manitoba and should be felt in the Red River Valley by early- to mid-morning.

Warm air will flood across southern Manitoba behind a sharp warm front this morning
Warm air will flood across southern Manitoba behind a sharp warm front this morning

This Week

Today’s weather will feel downright mild compared to the frigid conditions we’ve been experiencing for the past week. Temperatures will climb well into the minus single digits across southern Manitoba, with most locations having high temperatures just a few degrees below freezing. Some spots downwind of the Manitoba escarpment (e.g. Morden and McCreary) may get near or just above the freezing mark. Unfortunately, this warm-up will come at a bit of a cost, with snow likely today and tonight. The initial warm frontal passage this morning may be accompanied by a bit of light snow, with accumulations of 2 cm of less expected. As the parent low pressure system slides southeastward tonight, more snow is possible. An additional 2 cm could fall by Tuesday morning. This will seem like a “dusting” compared to the blizzard earlier this month, but could still be enough to cause traffic problems on untreated roads. Fortunately, it will be warm enough for road salt to melt most of the snow, significantly improving what could otherwise be a fairly icy commute. Winds will be southwesterly at 20-30 km/h today.

Tuesday will see mild conditions persist as the westerly Pacific flow remains over southern Manitoba. Clearing skies are expected throughout the day as today’s low pressure system moves off to the east. Highs will be similar to today’s, with values just below freezing in most areas. Winds will be westerly at 20-30 km/h.

Unfortunately, more snow is possible on Wednesday as another system passes through the region. There is still a lot of uncertainty regarding the track of this system, so it’s too early to pin down exactly how much snow should be expected and where it will fall. Models currently show the system tracking through southern Manitoba, with the heaviest snow almost right along its track. Areas under the heaviest band could see up to 10 cm, while surrounding areas will receive much lesser amounts. Winds will be easterly ahead of the system at 20 km/h, shifting to northerly at 30 km/h gusting to 50 km/h behind the system later in the day.

Long Range

It appears that mild conditions will persist for the remainder of the work-week before another cool-down arrives. Long range model suggest that another surge of arctic air may come down on or just before Christmas. It’s still too early to tell how long this next arctic blast will last, but unfortunately it’s looking like a pretty cold Christmas Day is on tap.

Bitterly Cold Weekend; Warmer Weather Next Week

Brad Leave a comment

The coldest temperatures of the winter are on their way to southern Manitoba as a reinforcing blast of Arctic air descends from the north. The cold snap will persist into the start of next week, but milder air is expected to arrive by Tuesday or Wednesday.

The next few days will be very quiet weather-wise other than the fact that bone-chilling cold is moving into the province. Winds for the next few days will be between 10-20 km/h out of the northwest slowly backing to southerlies by Sunday. Skies will be mainly sunny through the weekend.

Bitterly cold air will descend into Southern Manitoba this weekend.

The big story is the cold, shown above with the 850mb1 temperatures. The potency of this Arctic outbreak is highlighted by temperatures at this height reaching -30°C, a sign of a truly cold air mass.

This will result in temperatures dropping from a high near -21°C today to a low just below the -30°C mark. Temperatures will struggle to recover to the mid-minus 20's on Saturday before dipping to a low near -32°C on Saturday night. Sunday will see warmer air aloft working into the region, allowing temperatures to moderate towards around -22°C by late in the afternoon. Some cloud cover will begin working in through the afternoon and cloudy skies on Sunday night will bring the chance for some light snow with temperatures hovering around -23°C.

Wind Chill

Wind chill values will be a concern this weekend, likely reaching Environment Canada's warning criteria of -40. Winds slightly over 10 km/h both Friday and Saturday night will combine with low temperatures dipping below -30°C to produce wind chill values in the -39 to -44 range. Wind chills of this severity can result in frost bite on exposed skin in 5-10 minutes, so be sure to take precautions and layer well if you need to be outside at night.

As an aside, it's worth reminding people that wind chill is not a temperature. Wind chill describes what the temperature would have to be with no wind to lose body heat at the same rate as the actual temperature with wind. So wind chill of -40 produced by a night with temperatures of -29°C and a 15 km/h wind describes that the rate of heat loss in the actual conditions is the same as if it was -40°C outside with no wind.

Wind chill has numerous problems, but does serve as an imperfect method of communicating a very real thing.

But just keep in mind that it is not a temperature, but an expression of a rate of heat loss.

If you want to know more about wind chill, visit our article "The Problem With Wind Chill"

Long Range

Early next week will bring milder air back to the region. By mid-week, highs should be back into the -10°C to -5°C range. Before that warm air arrives, though, it's quite possible we'll see quite unpleasant conditions with moderate southerly winds making it feel much colder than the temperature would imply. That said, there's high confidence that the warm air will get here by mid-week, so if you can make it through this cold snap, more pleasant conditions await on the other side.

Winnipeg’s seasonal daytime high is currently -10°C while the seasonal overnight low is -20°C.

  1. This height is approximately 1.5km above sea level. ↩

Cold Becoming Colder

Brad Leave a comment

Those looking for a reprieve from the cold will have to wait longer. Temperatures are set to remain cold throughout the week with even colder air set to move into the region for the weekend.

Today will bring a little sun and a little cloud to the region with temperatures climbing to a high near -18°C. There will be a slight chance of some light flurries, particularly in the afternoon and evening, but it won't amount to anything substantial. Skies will be clear tonight with temperatures plummeting to a low near -29°C as another surge of Arctic air pushes southwards behind a cold front that passed through late Tuesday evening. It doesn't look like we'll crack -30°C at this point, but we'll likely be flirting with the value.

Thursday will bring sunny skies and cold temperatures as a ridge of high pressure settles over the region. With a high of just -21 or -22°C, Winnipeg will be nearly 8°C below normal for this time of year. Thursday night won't be as cold, however, as "milder" air from the Yukon spreads southwards and eastwards into the region. The overnight low should be around -24 or -25°C on Friday morning.

The RDPS is suggesting temperatures may fall below -30°C early Thursday morning, but other models suggest slightly warmer temperatures.

Friday will see a return to highs above the -20°C mark with temperatures climbing to -18°C or so. Skies will be fairly cloudy as that weak disturbance carrying the Yukon "warmth" moves through, and there will be a slight chance of some light flurries through the day. Again, nothing particularly notable with just a dusting of snow possible. Temperatures will drop to around -26°C on Friday night under mixed to cloudy skies.

Long Range

The weekend is looking fairly brutal as another cold front moves through on Friday and ushers another, more powerful shot of Arctic air into Southern Manitoba.

An outbreak of bitterly cold Arctic air is expected this weekend.

This winter blast will push all the way south into Oklahoma, ensuring that the entire eastern half of the Canadian Prairies is entrenched in bitterly cold air. At this point, it seems quite likely temperatures will fall below -30°C on Saturday night alongside a good chance of widespread extreme cold warnings from Environment Canada.

The light at the end of the tunnel, though, is that warmer air is forecast to arrive next week as a powerful surge of Pacific air sweeps eastwards across the Prairies, sending highs back up into the minus single digits. There's a lot of uncertainty at this point, and I think that models are generally warming Winnipeg up too quickly with the cold weather likely hanging on an extra day with very windy conditions out of the south before the mild air actually arrives.

It seems quite likely that more seasonal to slightly above seasonal temperatures will be in place for the week leading up to Christmas.

Winnipeg’s seasonal daytime high is currently -10°C while the seasonal overnight low is -20°C.