Tag: Snow

The Deep Freeze Gives Way to A Mixed Weekend

Brad Leave a comment

While temperatures across the Red River Valley this morning are extremely cold, a developing series of major low pressure systems set to impact Alaska will be responsible for pushing us out of the deep freeze and back towards more seasonal temperatures for next week.

12hr. QPF valid Saturday at Noon

The GEM-REG is showing around 1–2cm of snow across the Red River Valley by midday on Saturday.

Friday


Sunny. Increasing cloud overnight.
-24°C / -28°C

Sunny skies will dominate the Red River Valley for most of the day today as we remain under the influence of the Arctic high. Entrenched in the cold air under this high, temperatures today will climb up to about –24°C; this is some 13°C below the “normal”[1] temperature for this time of year. The strong northwesterly flow aloft that’s brought our cold air back will begin to waver tonight as a weak disturbance ripples down the jet stream towards Southern Manitoba. An Alberta clipper will rush across the Prairies tonight, pushing clouds into Southern Manitoba through the overnight period and preventing our overnight lows from dropping to anywhere near where they bottomed out last night. Overnight lows will likely sit at around –27 or –28°C tonight through most of the Red River Valley.

Saturday

Saturday

About 2cm of light snow.
-16°C / -28°C

As the Alberta clipper pushes through on Saturday, a broad area of light snow will move through the Red River Valley. This system will be rather moisture-starved with only ¼ to ½” of precipitable water to it’s name, so snow will likely be light with SLRs of only around 15:1 (relatively crystalline snow). This will all combine to produce only 1–2cm of snow despite the fact that it will snow most of the day. Temperatures will warm up to around –15°C as a little bit of mild air pushes into the province with this system, but temperatures will plummet right back to where we were before as the clouds clear out fairly quickly on Saturday evening and we head to an overnight low of, again, around –28°C.

Sunday


Mix of sun & cloud. Chance of flurries.
-20°C / -28°C

Skies will start off sunny on Sunday but another weak system tracking across southwestern Manitoba will spread some cloud into the Red River Valley midday. This disturbance will track through fairly quickly so we’ll likely see a chance of flurries (with better chances over southwestern Red River Valley) late in the morning into the early afternoon. The clouds will clear out by evening as we head to another cold night with temperatures dropping back to about –28°C. Heading into next week, the flow aloft begins to become significantly more zonal, allowing milder Pacific air to push further eastwards across the Prairies. Temperatures will generally be warmer but by exactly how much is still hard to tell. Ensemble predictions have moved from an above-normal temperature forecast next week into a more seasonal-looking pattern. Either way, we’ll certainly be leaving the temperatures we’ve seen over the past week behind for a while.

  1. It should probably be said that the “normal” temperature for late January in Winnipeg is most likely just an average of the extremes.  ↩

Bitter Cold Continues

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The bitter cold entrenched over Southern Manitoba will persist a few more days as another Arctic Ridge slides through the province.

850mb Temperatures valid Wednesday Morning

850mb temperatures valid this morning from the GEM-REG. A pool of bitterly cold Arctic air over the province will restrict daytime highs to the mid-minus-twenties today.

We’ll see an extremely cold day today with plenty of sunshine and a high only around –25°C. This is some 12–13°C below our normal daytime high for this time of year of –12°C. Temperatures will drop below –30°C tonight for a 3rd night in a row.

Light Snow on Thursday

Temperatures will continue to be cold on Thursday with a high near –21°C as a weak disturbance slides across the province in the northwesterly flow aloft. This will spread an area of snow across southwestern portions of the province early in the morning and into the Red River Valley near midday. With temperatures so low SLR values will likely be quite high, somewhere in the range of 20:1 to 25:1. This very high “fluffy factor” will help produce snowfall accumulations of 2–4cm by Thursday evening. Temperatures will climb to around –20°C on Thursday, aided by the cloud cover that will push in.

On Friday sunshine will return as we face another cold day with highs below –20°C. Fortunately, it appears that warmer air will finally be pushing into the region by Friday night. Temperatures look to drop only a few degrees from our daytime high as we then see much warmer weather on Saturday and Sunday as highs climb back towards the –12 or –13°C mark. It looks like we’ll see a mix of sun and cloud through the weekend, with a chance for another couple of cm of snow on Sunday.

A Little Snow Before The Coldest Weather This Winter

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Two batches of snow followed by the coolest temperatures of the winter are in store for Southern Manitoba over the next few days.

Clipper Snowfall Totals

Forecast snowfall totals from this clipper system across Southern Manitoba.

An Alberta Clipper will begin it’s march across the Prairies today, rapidly moving from Northern Alberta east-southeast into Northern Minnesota by tonight. This system will drag a warm front eastwards across Southern Manitoba, spreading 1–2cm of light snow across the Red River Valley. The snow will ease off this afternoon to just scattered light flurries as the weak leading impulse moves off into NW Ontario.

Temperatures will warm to around –8°C by this afternoon, with the warmer daytime highs near 0°C locked into the extreme SW portion of the province. A second shot of snow will push into the Red River Valley tonight as the main low centre of the Alberta Clipper moves through the region. Temperatures in the RRV will rise to –4 or –5°C by midnight before starting to drop as the cold front moves through. The bulk of the snow will start near midnight and taper off on Saturday morning with a further 3–5cm of snow accumulation for a total of 4–7cm by the time this whole system moves through.

A few flurries will be around on Saturday as Arctic air begins building into Southern Manitoba yet again. Fairly strong northerly winds gusting up to 60–70km/h will develop early Saturday morning which will result in significant blowing snow in the RRV outside the City of Winnipeg. “Ground blizzard” conditions will be relatively widespread, with particularly poor visibilities as low as 100–200m on west-east running roads, such as the Trans-Canada Highway from Winnipeg to Portage La Prairie. Given the already slick conditions of many roads around the province, be sure to give yourself plenty of extra time if you need to travel on Saturday. The winds will lighten up by mid-afternoon, marking the start of our entry into a major deep freeze. Bitterly cold Arctic air will be pushing southwards behind this clipper system, with temperatures falling to around –25°C by the end of the day. Temperatures will plummet tomorrow night, with overnight lows through the Red River Valley dropping to the –30 to –35°C range. Temperatures will rebound slightly on Sunday as a weak disturbance brings some cloud and a chance of a flurry or two, but even colder air looks to be pushing in on Sunday night.

If the models are to be believed (which I do have some hesitation at the moment), temperatures will drop through the day on Monday to nearly –30°C by the end of the day, with overnight lows dipping to nearly –40°C. I think that the models are getting a little too excited about how cold it will get. The GEM-GLB model’s overnight lows have been 5–6°C too cold over the past week, so it’s more likely that we’ll see lows closer to –35°C than –40°C. At that point, though, it’s colds enough that those numbers don’t even matter. It’s certainly going to be an extremely cold start to next week.

A Cold Second Half to the Week

Brad Leave a comment

Winnipeg will round out the second half of the week with some sun, some cloud, and and very cold temperatures.

Gonna be cold!

You might want one of these for the next little while…

On the backside of yesterday’s system that brought a quick 2–3cm of snow to Winnipeg, a deep pool of bitterly cold Arctic air is infiltrating southwards into the Red River Valley. With sunny skies and a breezy north wind, temperatures will plunge back below the –20°C mark today, bottoming out early this afternoon around –23 or –24°C. Winds will (mercifully) ease off around lunch time, which will minimize wind chill. Temperatures will drop further tonight, with overnight lows dropping below –30°C entirely possible through the Red River Valley, although Winnipeg will likely bottom out at “only” –28 or –29°C.

850mb Temps Thursday Morning

850mb temperatures for Thursday morning from the GFS model. A sharp boundary will slice across the Prairies with pleasant, mild air over the southwestern half and bitterly cold Arctic air over the northeastern half.

Thursday will bring another cold day with plenty of sunshine. The daytime high will struggle to reach –22°C with a light wind out of the south that will increase to around 20km/h by the end of the day. This will keep things feeling closer to around –27 or –28 for much of the day. Proving that the weather can be merciful at times, clouds will begin to roll in Thursday night ahead of the next push of warm air from Alberta. The timing of the cloud cover will strongly impact what the overnight low will be; the sooner the clouds move in, the warmer the overnight low is. At this point, it looks like the temperature will bottom out around –25°C.

Why do clouds impact overnight lows? Clouds can make a big difference for two reasons. First, they act like a big blanket; as the ground radiates heat upwards and cools off, instead of escaping off into the upper atmosphere, it is trapped closer to the surface. This dramatically slows the rate the temperature will cool off. Secondly, clouds radiate heat, generated through internal processes and absorption of the energy the surface is releasing, towards the ground. This also helps to slow down how quickly the temperature drops, or in some cases, even warm it up a little.

On Friday we’ll be under the influence of the next impulse coming across the Prairie. While we won’t get to see the warm air with this system, it’s proximity to us will at least warm us up to around –13 or –12°C. There will likely be periods of light snow across most of the Red River Valley with 2–3cm accumulations likely by the end of the day.

Light snow will persist through the night into Saturday morning. Saturday will bring with it gusty northwesterly winds as things clear out and that bitterly cold Arctic air re-establishes itself over the region. Up to another 2–3cm are possible on Saturday before things clear out. Sunday looks to be sunny and very cold, with daytime highs near –24°C.