Category: Forecasts

Bitter Cold Returns to Manitoba

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Another shot of bitterly cold air is poised to crash through Manitoba this weekend with daytime highs plummeting back into the -20’s and overnight lows dipping close to -30°C.

The cold snap this weekend is looking slightly different from earlier in the week and now comes with some good news, some bad news, and a bit more uncertainty. The overall pattern has shifted further west, with the core of the coldest air now forecast to slump southwards over the Saskatchewan/Manitoba border instead of the Red River Valley. This will shift the coldest temperatures westwards, which results in the good news for Winnipeg: it likely won’t be quite as cold as it looked earlier in the week, but just by a couple degrees. The bad news, however, is that there will be a bit more wind throughout the Red River Valley as the light winds in the centre of the ridge shift west with the coldest air.

RDPS forecast of surface temperatures and wind, valid Saturday January 16, 2016 at 12Z
The RDPS forecast shows very cold temperatures across much of the Prairies on Saturday morning with the main ridge axis running from Northern Alberta through Southern Saskatchewan.

The cold air begins working in today; temperatures will climb to around -19°C today for the daytime high, and then top out between -23 and -21°C on Saturday and Sunday. Overnight lows over the coming days will likely be around -28 or -29°C for the coming 3 nights, depending on "the uncertainty."

The complicating factor with the ridge of high pressure pushing further west will be cloud cover. Two aspects complicate the fair sky forecast:

  1. Uncertainty in how much cloud cover will remain on the east side of the ridge. Many of the Arctic ridges this winter have been "dirty ridges," that is, they are "polluted" by significant amounts of low-level cloud. There are some indications that this may be the case with this next system, but to a much lesser extent compared to others this winter based on satellite imagery of upstream conditions.
  2. Complications with an inverted trough rotating through Central Manitoba. While much of the province will be under the influence of the Arctic ridge, several forecasts show a weak inverted trough associated with a system rotating through Ontario digging into the ridge through Central Manitoba. This feature could produce more cloud that would gradually slump southwards into the Red River Valley.

The biggest uncertainty with cloud cover is Saturday. My best guess at this point is that we’ll see a bit of cloud, however it will overall be a mixed-sky to sunny day. There is an off-chance, though, that we end up mainly cloudy. Cloud cover can marginally impact the daytime high (likely increasing it by around 2°C), and substantially impact overnight lows (keeping them significantly warmer than in clear skies).

That said, with winds likely between 10-20 km/h at night, wind chill values in the -35 to -40 range will be widespread over Southern Manitoba over the coming nights, with -40 or colder wind chills quite likely over southwestern Manitoba. Here in the Red River Valley, -40 wind chills seem unlikely, but could be seen if temperatures get a couple degrees colder than forecast at night or the winds are a tad stronger. Environment Canada issues extreme cold warnings when the wind chill *or* temperature is expected to drop below -40.

Sunday has more confidence in seeing mainly sunny skies.

Long-Range Outlook: Hints of Warming

The first half of the coming week still looks quite cold with daytime highs near -20°C and overnight lows in the -25 to -30°C range. By mid-week, however, it looks like a big change will be on the doorstep.

NAEFS 8-14 Day Temperature Anomaly Forecast – Valid January 22 - 29, 2016
NAEFS 8-14 day temperature anomaly forecast, valid January 22 – 29, 2016

Current long-range forecast models are beginning to show with higher confidence that the polar vortex will finally be displaced allowing a milder zonal flow to develop. While it doesn’t look like a huge surge of warm air, seasonal to slightly above seasonal temperatures by the end of the week look fairly reasonable.

Right now, the average daytime high is -13°C and the average overnight low is -24°C.

Milder Weather Ahead, But Deep Freeze Looms

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A few morning flurries will mark the arrival of slightly milder air than has been in place over Southern Manitoba over the past several days, however the reprieve will be brief as another potent blast of Arctic air spills southwards for the weekend.

This morning will start off with a few flurries tapering off as a weak disturbance shunts by to the south of Winnipeg, leaving behind mainly cloudy skies for the day. There will be a slight chance of continue flurry activity through much of the day thanks to favourable snow-making temperatures throughout the depth of the cloud cover, but with the lack of any real focus for the snow, it will be very light if it occurs and pose no likelihood of any accumulation. Temperatures will be slightly milder than the highs near the -20°C mark that have been in place over the last few days; today’s high should climb to around -15°C with light southerly winds while the low tonight drops to around -19°C under mostly cloudy skies.

Thursday will bring a pair low pressure system through the province; the first skirting through the southwestern corner and the southern Red River Valley before exiting into Minnesota while the second drops down from Northern Manitoba, eventually merging into the first low near Lake Superior. This makes the forecast a little bit trickier, but fortunately neither system will bring particularly significant weather with it. The southern low will produce a swath of 2-3cm of fresh snow through southwestern Manitoba into the southwestern Red River Valley, while areas to the north and east see some light flurry activity.

RDPS 12hr. Precipitation Accumulation for Thursday
The RDPS is showing the main swath of snow from Thursday’s system well to our south…perhaps too far south.

Winnipeg appears to be near the edge of that, so throughout the day on Thursday we’ll likely see fairly cloudy skies with a chance of some flurries or perhaps even some light snow if the whole system pushes a little further to the east. Temperatures will climb a little higher than today, with a high temperature near -13°C expected.[1] Skies will remain fairly cloudy on Thursday night with a chance of flurries; the overnight low should be near -22°C.

With the low pressure systems off to our southeast, all that will be left is for the Arctic air to begin building back into the region unimpeded. This next shot of cold looks, at this point, to be colder than the last by a couple degrees. Friday will mark the entrance of that air, with northwest winds near 15-20km/h and a high near -19°C under partly cloudy skies. The overnight low on Friday night will sit near a very chilly -28 or 29°C.

Bitterly Cold Weekend Ahead

This weekend will be particularly cold thanks to a deep Arctic air mass that will slowly move through the region.

850mb Temperature Forecast for January 15-18, 2016
This animation of 850mb temperatures from Friday morning to Sunday morning shows the bitterly cold air moving over the province.

It will begin moving in on Friday, the core of it will be over Winnipeg on Saturday, and then it will begin shuffling off on Sunday. Unfortunately, as these systems move to the southeast, temperatures here at the surface tend to stay quite cold despite the warmer air moving in aloft thanks to an outflow of cold air out of the ridge to our south.

This will mean daytime highs likely around -24 or -23°C this weekend with overnight lows in the -28 to -30°C range. There’s also some indications that there will be 10 to 20 km/h winds through the weekend, which would likely mean Environment Canada would issue extreme cold warnings for wind chill values at night in the -38 to -44 range.

Temperatures will begin to moderate back towards -20°C or the low minus teens early next week.

  1. It’s worth noting that this system will have quite a sharp temperature boundary associated with it, so if everything were to shift east a bit we could see temperatures climbing above -10°C in Winnipeg; conversely, if it were to track further west, we could see daytime highs limited to around -17°C.  ↩

Cold Weather Continues

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The cold weather continues in Winnipeg for much of this week with only a brief respite mid-week of some near-seasonal temperatures. Snow-wise, a weak system moving through today will bring a couple centimetres of fresh snow, but otherwise no significant snowfall is in the forecast.

Today’s weather will be dominated by a weak shortwave disturbance sliding southwards through the province. Light snow will push into the Red River Valley from the northwest this morning and taper off this evening. Accumulations will be relatively low with this snow; for the most part, just 1-2cm is expected to accumulate. As the system begins heading past us this afternoon, gusty northwesterly winds to 20-30km/h will develop, making it feel more like the minus 30’s than the high of -20°C.

Multi-spectral satellite imagery of approaching low pressure system.
This morning’s satellite imagery reveals the low pressure system that will slump to the southeast and bring light snow to the region today.

Behind this system, another Arctic ridge will build into the southern Prairies, reinforcing the cold air. Here in the Red River Valley, temperatures will dip to around -26°C tonight with wind chills in the -33 to -37 range. In the southwest corner of the province, temperatures could fall as far as -30 to -31°C, which would result in wind chills near or slightly below -40.

Tuesday will be a fairly quiet day over Winnipeg & the Red River Valley with mixed skies and a high near -20°C. Winds will be fairly light.

The next system moving into the Prairies will spread cloud across Southern Manitoba on Tuesday night, somewhat limiting our overnight low to around -24°C.

3hr QPF from the RDPS valid overnight Tuesday.
This forecast from the RDPS for Tuesday night shows a broad warm front pushing into Manitoba with an area of light snow ahead of it.

Wednesday is a bit trickier, but either way things pan out, the weather won’t be too significant. The big story will be that near-seasonal temperatures will finally move into the Red River Valley with daytime highs climbing into the -13 to -15°C range. Skies will be mainly cloudy.

Depending on how far east the disturbance moving through the region pushes, we may see some light snow through the day. If it remains to our west, as guidance suggests, it seems probable that we could see some very light flurry activity across the region.

Temperatures will remain comparatively mild on Wednesday night with overnight lows near -20°C.

Colder air is set to return for the second half of the week with another shot of sub-20°C high temperatures likely this weekend.

Arctic Chill Settles Over Manitoba

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Winnipeg will see some of the coldest weather of the winter as Manitoba falls under the influence of the infamous Polar Vortex. Unlike other brief cold snaps seen this winter, this cold spell looks to be rather persistent, with only one brief warm-up on the horizon before the Arctic air returns.

Today will start with a few remaining flurries pushing out of the region as a cold front sweeps through the province. Winds will be out of the northwest at 20-30km/h for much of the day. Once the flurries move out this morning, the Red River Valley will be left with mainly cloudy skies and falling temperatures. By late this afternoon, the temperature will sit around -18 or -19°C.

Skies will remain fairly cloudy tonight as temperatures dip to -26°C.

Forecast 850mb Temperatures — RDPS 00Z Jan 08, 2016
The core of the coldest air in North America will be anchored over Manitoba on Saturday morning.

Saturday will mark the full arrival of the Arctic air. The high temperature will be limited to only -21°C with light northwesterly to westerly winds. There’s some uncertainty as to how much cloud cover will remain in the area, but it appears that we’ll likely see mixed skies here in Winnipeg. A little bit of clearing will move in on Saturday night as temperatures dip to around -25°C.

Sunday will continue the cold trend with daytime highs near -20°C under partly cloudy skies and light south to southwesterly winds. Sunday night will continue seeing partly cloudy skies with a low near -25°C.

Weather Roller Coaster Next Week

Unfortunately, next week doesn’t look to offer too much of a reprieve from the cold. This outbreak of colder weather has been driven by a weakening of the Arctic Oscillation (AO) which has allowed colder air to spill southwards. Despite the strong El Niño, the reality often is that cold air is king, and it’s managed to shunt out the warm air. The coming week will be a battleground between the blocking pattern of the Polar Vortex and the attempt for a more typical El Niño pattern featuring warmer weather and a more progressive pattern.

The first half of next week looks fairly cool with daytime highs in the -15 to -20°C range and a slight chance of snow on Monday into Monday night. There is hope for a more substantial warm-up mid-week, however.

A surge of significantly warmer air is expected to spread eastwards on Tuesday with some light snow associated with it. General consensus is that an Alberta Clipper will develop over Northern Alberta and then race southeastwards along the baroclinic zone, flattening it out and sweeping cold air southwards in its wake.

Exactly how warm it manages to get in Winnipeg will depend substantially on the timing and exact location of the setup. Some forecasts show the warm air fully pushing into the region and resulting in daytime highs mid-week near -8°C, while others have a more southerly track and occlude the warm air out to the south quickly and keep temperatures fairly cold.

After the passage of the clipper and any associated snow, the Polar Vortex is expected to retrogress and usher another shot of very cold air into Manitoba.