In Like A Lion

March will be coming in like a lion as one of the coldest winters in our lifetimes continues on with no end in sight. Some of the coldest temperatures of the season are poised to return as yet another reinforcing blast of Arctic air slumps southwards over the region.

Friday
-19°C / -35°C
Flurries ending midday then clearing and windy.

Saturday
-25°C / -32°C
Sunny & cold.

Sunday
-22°C / -30°C
Sunny.

Flurries Give Way to Deep Freeze

A weak inverted trough moving through Southern Manitoba this morning is spreading flurries across the entire region. The remainder of the snow and cloud will clear out midday as we head to a daytime high of -19°C. Unfortunately, the clearing skies are symptomatic of a brutal blast of Arctic air slumping southwards that will bring us yet another night with overnight lows dipping towards the -35°C range.

850mb temperatures show clearly the next lobe of very cold air slumping into the Southern Prairies.
850mb temperatures show the next lobe of very cold air slumping into the Southern Prairies.

As we move onto the backside of the inverted trough this afternoon, strong northerly winds will move into the region – increasing to 30-40km/h with gusts to 60km/h – and produce localized blowing snow throughout the entire Red River Valley. The situation will resemble the clearing and strong winds we received on Wednesday, however today won’t be as intense as that event.

Winds will taper off this evening alongside our plummeting temperatures as another Arctic ridge of high pressure makes its way into the region. This ridge of high pressure will be driven by a lobe of extremely cold air aloft rotating southwards over the Prairies. Temperatures at 700mb through the core of the cold air is forecast to be in the -35 to -40°C range which puts it as the coldest air in the entirety of the northern hemisphere. This extremely cold air will push our overnight low to around -35°C and combine with winds that will remain around 15km/h to produce extreme wind chill values in the -45 to -50 range.

Sunny and Cold Weekend

Conditions through the rest of the weekend will be benign and cold. Mainly sunny skies will dominate with winds generally between 15-25km/h. Saturday’s daytime high of -25°C will be some 20°C below the seasonal daytime high for this time of year. Sunday will warm to around -21 or -22°C for a daytime high, still well below normal. Overnight lows will dip just below -30°C both nights.

Cold Weather Continues

Unseasonably cold weather will continue through the next week as temperatures very slowly warm. By the end of next week temperatures look to climb back to around -10°C with the chance for a couple of shots of snow through the second half of the week.

The NAEFS 8-14 Day Temperature Outlook
The NAEFS 8-14 Day Temperature Outlook

It does look like this miserable pattern begins to break down next weekend into the following week, allowing more seasonal air to push back into our region. The NAEFS 8-14 day temperature outlook is also picking up on the pattern change and finally showing a return to seasonal temperatures.

So be brave; we only need to make it one more week and what is almost surely the last extreme cold snap of the season will be past. This winter has been brutal and will easily sit in the top 3 coldest winters of the last 100 years. Lets all hope that we can shift into a steadier mild pattern through mid-March and start getting rid of this snow.

Environment Canada Dates Changes to Warning Program

Environment Canada released a notice today that dates some significant changes to the weather warning program in Canada. The notice touches on several key areas, however the most noticeable will be the changes to watch/warning types:

WARNING AND ADVISORY CHANGES

BLOWING SNOW ADVISORY
REPLACES
BLOWING SNOW WARNING

FREEZING DRIZZLE ADVISORY
REPLACES
FREEZING DRIZZLE WARNING

FROST ADVISORY
REPLACES
FROST WARNING

EXTREME COLD WARNING
REPLACES
WIND CHILL WARNING

ALSO THE EXTREME HEAT WARNING
REPLACES THE FOLLOWING:
HUMIDEX ADVISORY
HIGH HEAT AND HUMIDITY WARNING
HUMIDEX AND HEALTH ADVISORY
EXTREME HEAT-WAVE ADVISORY

NEW ADVISORIES ADDED (ENGLISH):
=NEW= FOG ADVISORY
=NEW= WEATHER ADVISORY

Several warnings are being downgraded to “advisory” status: blowing snow warnings, freezing drizzle warnings and frost warnings. It’s unclear whether these advisories will be handled through a Special Weather Statement (SWS) or if a new bulletin type will be started. I’m guessing they’ll be addressed as a SWS which could be problematic since SWS visibility has always been a bit of an issue. I can’t complain too much about the changes, although I feel that the blowing snow warning is being mishandled.

In 2012, Environment Canada tightened up the requirements for blizzards[1] to the point where warning-eligible events rarely ever happen on the Prairies. As a seeming acknowledgement of this fact, the blowing snow warning was introduced with slightly more lax requirements[2]. The blowing snow warning has been used substantially in Southern Manitoba where ground blizzards – blizzards that occur with no falling snow – are relatively frequent through the winter months. They generally don’t qualify for blizzard warnings because they are too short-lived or difficult to verify – especially since no weather sites along/south of the Trans-Canada Highway other than Winnipeg, Portage la Prairie and Brandon have visibility sensors.

These events can be quite significant and end up closing major highways. The idea that they’ll be regulated to a special weather statement seems disingenuous to their potential impact. Granted, this is mostly speculation at this point, so it will be interesting to see how they decide to handle advisories going forward[3].

Regarding Extreme Cold Warnings replacing wind chill warnings, I recently wrote a lengthy post that addresses this change and explores, in depth, the problems with wind chill and wind chill warnings.

The Extreme Heat Warning looks like an attempt to unify the way extreme heat is handled across the country. Currently some regions do humidex advisories (we use those here in the Prairies), some use high heat and humidity warnings, some use humidex and health advisories and some use extreme heat-wave advisories. The unification into a single banner for hot, humid weather seems like smart housekeeping.

Lastly, Fog Advisories and Weather Advisories will be added to the repertoire. Fog advisories will be great since there’s currently no official way to highlight significant fog events that can have dramatic impacts on transportation. I’m not entirely sure what a “weather advisory” will be, and as such I imagine we won’t see it much.

One of the other small changes which will likely be most obvious in severe thunderstorm warnings will be the inclusion of certainty of predicted severe weather hazards. This means that in a warning they could tell you that 2” of rain is certain, nickel-sized hail is likely and that there’s a slight chance of a tornado; or they could say that a tornado is certain and there’s a slight chance for dime-sized hail. This is a great step forwards into beginning to convey context in the weather forecast.

All of these changes will be implemented on April 8, 2014.


  1. Changed the required visibility from 1/2SM or less to 1/4SM or less. The requirements of sustained winds ≥ 40km/h and a duration of 6hr. or longer remained unchanged.  ↩
  2. A blowing snow warning requires visibilities of 1/2SM or lower (as opposed to 1/4SM for a blizzard), winds ≥ 30km/h (as opposed to 40km/h for a blizzard) for at least 3 consecutive hours (as opposed to 6 for a blizzard).  ↩
  3. From a developer standpoint, there’s no easy way to even check to see if a special weather statement is in effect for a site. It would be nice if Environment Canada included them in the same feeds for watches and warnings.  ↩

Wind and Blowing Snow Usher in Arctic Blast

A deep trough of cold air anchored over Hudson Bay will lock Southern Manitoba into a strong northerly flow that will keep us stuck in abnormally cold weather well into March. This latest blast of cold weather will ensure that the winter of 2013/2014 ends up as the coldest in 35 years[1] and as one of the 15 coldest winters on record[2].

Wednesday
-17°C / -34°C
Chance of morning flurries, then very windy w/blowing snow.

Thursday
-21°C / -26°C
Sunny. Increasing cloud & flurries overnight.

Friday
-21°C / -34°C
Flurries ending midday then clearing.

The Red River Valley is in for a rude return to the deep freeze today as a cold front rips through the Red River Valley bringing very strong winds with it. There’s a very slight chance of some light flurries in this morning’s cloud but it’s likely any precipitation that might develop will remain north or east of the valley. The bigger story is the cold front that will push through around lunch time today.

A deep unstable layer will develop this afternoon in the wake of the cold front.
A deep unstable layer will develop this afternoon in the wake of the cold front.

The passage of the cold front will clear out the skies but bring with it very strong winds, increasing out of the north/northwest to 50km/h. A deep layer of instability, shown on the right in the forecast sounding, will work in two ways:

  1. It will promote gusty winds which will mean in addition to the sustained winds at 40-50km/h, it’s quite likely we’ll see gusts in the 60-70km/h range.
  2. The instability will help “loft” ice crystals and snow which is helpful in generating blowing snow.

Other than making it feel miserably cold, the wind will work together with the relatively dry snowpack in the area to produce blowing snow. I’m unsure of exactly what the snowpack surface’s nature is right now, but I think it’s safe to say that with winds as strong as we’ll see, some blowing snow is inevitable. I don’t foresee a full-scale blizzard or anything of the sort, but localized white-out conditions are certainly possible. If you’re travelling on area highways this afternoon, be aware of the potential for poor driving conditions.

The winds will ease off through the night as an Arctic ridge of high pressure pushes into the region. Temperatures will plummet close to -35°C through the Red River Valley by tomorrow morning as we become entrenched in bitterly cold air once again.

Tomorrow will bring mainly sunny skies, relatively light winds and a high near -21°C. A weak inverted trough will begin pushing into Southern Manitoba late late in the day and will spread cloud and light flurries into Winnipeg and the Red River Valley overnight. Temperatures will drop only to around -25 or -26°C overnight thanks to the cloud cover.

Friday morning will see the light flurry activity tapering off with clearing skies towards midday as the trough pushes off to the east. With the sunshine will come wind once again, with north/northwesterly winds at 30-40km/h picking up through the afternoon. We’ll climb once again to around -21°C as a high

Entrenched

The NAEFS 8-14 day temperature outlook.
The NAEFS 8-14 day temperature outlook.

Buckle up for the long haul; the cold air will be settling into the region for an extended stay. All long-range outlooks – including the NAEFS above – are forecasting below-normal temperatures into the second week of March. Of note is how far below-normal we’ll be this week. The seasonal high for this time of year is around -6°C, and with forecast highs of -21°C, we’ll be some 15°C below normal.

So keep the long johns out, plug in the car and keep warm!


  1. As mentioned by Rob’s Obs on February 24, 2013.  ↩
  2. Records began in 1872 at St. John’s College  ↩

Unseasonably Cold

Southern Manitoba has a long stretch of benign, significantly cooler than normal[1] weather ahead as a large upper-level low entrenches itself over Hudson Bay.

Monday
-16°C / -25°C
Chance of a morning flurry, otherwise mainly sunny.

Tuesday
-21°C / -25°C
Mainly Sunny

Wednesday
-15°C / -31°C
Chance of a morning flurry, then clearing.

A large storm that pushed up through the eastern United States late last week has stalled out over Hudson Bay and is all set to make things miserable for us over the next couple weeks. Temperatures won’t be quite so bad to start the week thanks to a somewhat disorganized upper-level flow over the Eastern Prairies, but things will go from “disappointing” to “cabin fever” mid -week as a pipeline of Arctic air sets up and daytime highs plummet back below -20°C.[2]

The 500mb flow will organize as the week progresses and allow colder air to push into the province.
The 500mb flow will organize as the week progresses and allow colder air to push into the province.

There will be a slight chance of a flurry this morning as some of the last remaining cloud clears out from the Red River Valley and then we’ll see mainly sunny skies through most of the day as the temperature climbs up to around -16°C. The wind should be a little lighter than the past few days out of the west/northwest at 20-30km/h. Temperatures will drop to around -25°C tonight under clear skies.

Tuesday will bring colder weather with a high only around -21 or -20°C under mainly sunny skies and with breezy winds at 30-40km/h out of the northwest. Temperatures will drop to around -25°C overnight with some cloud pushing into the Red River Valley as a weak low pressure system approaches from the north. We’ll see a slight chance of flurries late overnight into Wednesday morning before the cloud clears out and we’re left with mainly sunny skies. Winds will start off relatively light but increase to north/northwesterly at 30-40km/h again once the cold front passes through. Temperatures will dip down to around -31°C on Wednesday night under clear skies.

The NAEFS 8-14 day temperature outlook.
The NAEFS 8-14 day temperature outlook.

Things look to remain cold for the foreseeable future with below-normal temperatures being forecast by the NAEFS all the way to two weeks out. In addition to the cool temperatures, things should be fairly benign weather-wise with no significant storm systems in the near future. It looks like there may be a couple cm of light snow on Friday as a weak inverted trough slides across Southern Manitoba, so we’ll keep an eye on that and how things develop. No big storms on the horizon, so just bundle up and enjoy the sunshine!


  1. Seasonal daytime highs for mid-February are -6°C and seasonal overnight lows are -16°C.  ↩
  2. Some 15°C below normal!  ↩