Windy Transition to Mild Weather

Warmer weather is on the way for the weekend with temperatures soaring close to the freezing mark, however not before a blustery day that will be rather miserable and may impact transportation throughout the Red River Valley.

Windy Weather Developing

Windy weather is on the way for Winnipeg today courtesy a developing low pressure system pushing eastwards across the Prairies. As this system moves towards Manitoba, a strong pressure gradient will develop over the Red River Valley between the incoming low pressure centre and departing ridge of high pressure. As the gradient strengthens in the afternoon, strong southerly winds will develop throughout the Red River Valley.

Strong winds are expected by Friday evening through Southern Manitoba and the Northern Plains
Strong winds are expected by Friday evening through Southern Manitoba and the Northern Plains (the highlighted area).

Sustained wind speeds will increase to 40-50 km/h by the early evening. It seems fairly probable given the near-constant light snow and ice crystals that have fallen over the last several days that blowing snow will become a transportation issue for Friday night into Saturday morning. In Winnipeg it shouldn’t be too bad, but in rural areas, particularly along west-east running highways, the potential for near-whiteout conditions exists. Be sure to give yourself extra time and carry a winter survival kit if you will be travelling on area highways.

Warmer Weather Brings Risk for Freezing Rain or Drizzle

Winds will begin tapering off on Saturday morning as the low pressure system arrives, bringing with it a blast of mild Pacific air. Despite the fact that skies will remain cloudy for most of the day, temperatures will soar to a high of -1°C.

Alongside the surge of warm air will come a risk of some freezing rain. An above-freezing level (AFL) will develop overnight, and by morning an area of precipitation is expected to slide through Parkland Manitoba, the Interlake and northern Red River Valley before sliding eastwards into Northern Ontario.

YWG Forecast Sounding valid Saturday morning from the NAM
This forecast sounding for Winnipeg from the NAM shows a well-defined AFL with Tw ≥ 0°C.

With sustained warm air advection and a wet-bulb temperature above 0°C in the AFL, the potential for organized freezing rain exists. The highest likelihood lies over the Swan River region and then southeastwards through the Interlake. The risk exists over the Red River Valley, but at this point it doesn’t appear that actual amounts will be particularly high. Nonetheless, it doesn’t take much freezing rain to make things slick, so we’ll monitor things and provide an update if the threat for the Red River Valley increases.

Behind the warm front, freezing drizzle will be possible throughout much of the day with saturated low-levels and the lift associated with the incoming low. Winds will be calm through the afternoon.

Winds will shift to the northwest in the evening as a cold front passes through. Skies will remain fairly cloudy and the threat for freezing drizzle will persist well behind the cold front and through much of the night. Temperatures will drop to around -8°C by Sunday morning.

Sunday will bring weak cold air advection through the day, resulting in temperatures rebounding only slightly if at all through the day. The chance for flurries will redevelop as temperature profiles become too cold for freezing drizzle and more favourable for snow. That said, overall moisture supply will be dwindling, so at this point it appears that there will be just a chance for some flurries.

Sunday night will bring cloudy skies and a low near -10°C.

Seasonal Weather Leads To Blustery End of Week

Winnipeg will see near-seasonal temperatures over the coming days with some light flurry activity mixed in before a big warm-up moves in for the weekend. The transition to warmer weather won’t be particularly graceful, however, as a howling southerly wind develops on Friday, making for a rather unpleasant shift.

The weather in Winnipeg through today and tomorrow will be dominated by the gradual arrival of a weak Arctic high that will slowly build southeastwards out of the Northwest Territories across Saskatchewan and Manitoba. Weak is the key descriptor of this ridge; it will bring with it little in the way of cold air nor will it be able to muster up much clearing either.

That said, today’s weather will be relatively pleasant, all things considered. Skies will be mainly cloudy through the day with some occasional light flurry activity. Temperatures will climb a little bit from where we start off to about -10°C with fairly light winds throughout the day. Tonight will continue to bring mainly cloudy skies—although a few clear breaks are possible—and temperatures dipping down to about -18 or -19°C. If more clearing develops than is expected at this point, the overnight lows could dip closer to about -23°C.

Tomorrow will bring very gradual clearing to Winnipeg with the morning likely starting off fairly cloudy and slowly becoming mixed to mainly clear throughout the day as the Arctic ridge slides into the Red River Valley. With the arrival of that system, the daytime high tomorrow will be cooler at around -15°C with a light northerly wind. There’s a slight chance of some flurries through the early morning, but for the most part no precipitation is expected on Thursday. Expect a low on Thursday night near -21°C under partly cloudy to mixed skies.

Friday will be…unpleasant. As many who have lived in Winnipeg for a while know, whenever a big warm-up is on the way there is often "the day" before the warm weather arrives; a day where it’s rarely as nice as it sounds like it’s going to be and those famous southerly winter winds make an appearance. Friday will be that day.

As the Arctic ridge pushes past and moves to our southeast, it is quickly replaced by a strengthening low pressure system moving across the Prairies. As the low moves into eastern Saskatchewan and begins spreading warmer air aloft over Southern Manitoba, its relatively close proximity to the Arctic ridge will result in a tight pressure gradient over the Red River Valley, oriented very favourably for the development of strong southerly winds. While starting the day off light, the winds through the Red River Valley will increase to around 30 gusting 50 km/h by noon, and then further strengthen to 40-50km/h gusting to 70km/h by the evening hours.

GDPS MSLP & Surface Wind Forecast for Friday
The GDPS shows the strong southerly winds (emphasized in yellow) expected over the Red River Valley on Saturday.

Temperatures will gradually climb to around -12 or -11°C by late in the afternoon—although it will feel closer to -25 throughout much of the day due to the wind chill. Temperatures will continue to rise overnight as the warmer air finally begins working its way into the valley; by Saturday morning the temperature is expected to climb to about -8°C in Winnipeg.

With strong warm air advection aloft and the surface flow dominated but the outflow from an Arctic ridge, it’s likely that Friday will be fairly cloudy as stratus streams northwards out of the ridge.

Warm Weekend Ahead

This weekend looks beautiful with temperatures well above seasonal expected throughout the Red River Valley. In Winnipeg, the temperature is expected to climb all the way to around the freezing mark under mainly cloudy skies. Sunday looks fairly nice, perhaps evening bringing some sun to the region, with daytime high closer to the -5°C mark.

Temperatures are expected to return to seasonal values for the start of next week.

Gradually Warming Up This Week

The early part of this week will remain very cold, but gradual warming is expected as the week progresses.

A surface ridge of high pressure will be centred over southern Manitoba on Monday
A surface ridge of high pressure will be centred over southern Manitoba on Monday

Monday

A surface ridge of high pressure will be centred over southern Manitoba today, continuing the chilly conditions that have plagued us for some time. The only good part about this ridge is that it will bring light winds to the region, at least keeping wind chill values at bay. High temperatures in southern Manitoba are expected to be near the -20C mark today under clearing skies. There is a slight chance of flurries early in the day before the clouds clear.

Tuesday

Tuesday will see slightly warmer weather in southern Manitoba as the surface high moves off to the east. Skies will be mainly cloudy, helping to maintain these slightly warmer conditions. Due to the presence of these clouds we may see some light flurry activity, but only trace accumulations will be possible. Winds will be noticeable stronger than Monday, with values of 20-30km/h out of the south.

Wednesday

Wednesday will remain mainly cloudy as a weak low pressure system approaches. We may again see some flurry activity throughout the day, but large accumulations are not expected. Some models bring measurable, but still light, accumulations of snow to southern Manitoba on Wednesday, so don’t be surprised if this forecast changes a bit. Winds will be generally light and from the south.

Long Range

The long range forecast shows us continuing to warm as we approach the weekend. Models suggest that late January will generally be warmer than normal (the normal high is currently around -13C). The current El Nino in the Pacific Ocean is hovering around record levels, thus we can expect it to begin more profoundly exerting its influence on our weather again before this winter is over.

Bitter Cold Returns to Manitoba

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.