Sunday, December 17, 2017

Mild weather continues Monday.. then turning colder this week with coldest airmass of the season moving in by Christmas

The relatively mild weather over the first half of December across southern MB will continue for one more day Monday, before significantly colder weather moves in this week. Even colder weather is expected by next weekend as the coldest airmass of the season so far pushes in across the Prairies for the Christmas holidays.

Temperature forecast for Winnipeg over next 10 days shows cold trend
setting in this week, with temperatures near -30C possible by Christmas
(graphic from weather.us)



In the short term, a westerly push of mild air will sweep across southern Manitoba Monday pushing temperatures up to the 0 to +1C mark over southern Manitoba, including Winnipeg. There may be some wet snow pushing across areas south of the TransCanada highway to the US border Monday morning through midday as a weak disturbance pushes through. In the wake of this system colder air will move into southern MB for Tuesday with temperatures dropping to the -10C mark by late afternoon. This will be the start of a period of much colder weather with temperatures near -20c expected by Wednesday morning. Highs Wednesday through Friday will only be in the minus teens with lows near -20C which is actually about average for this time of year (Normal hi -10C, low -20c)

Frigid weather expected for Christmas holidays

850 mb temperature forecast by European model for Christmas morning
shows massive Arctic vortex pushing across Manitoba with temps near -30C
(graphic from weather.us)
Unfortunately, things look to get even colder by next weekend just in time for Christmas as a massive push of Arctic air plunges south ushering in the coldest airmass of the season so far into southern Manitoba. This will bring daytime temperatures only in the minus 20s, with overnight lows  around -30C or lower.  Windchills may push into the warning criteria of -40 or lower at times over the Christmas holidays. Weatherwise, it looks mainly dry with no major storms or snowfall expected over the holidays with Arctic high pressure in place, so travel conditions should be okay across southern Manitoba. Otherwise, be prepared for frigid weather as you make your holiday plans!

Forecast temperatures Christmas morning shows widespread temps
of -30 to -35C across much of Manitoba with local -40C possible

(graphic from weather.us)
Surface map for Christmas morning shows massive Arctic high (1062 mb!)
over southern Saskatchewan driving frigid Arctic air across Manitoba
(graphic from tropicaltidbits.com)

10 comments:

  1. Some impressive cold already this morning, and we haven't even got into the deep Arctic airmass yet! Lows of -30C out towards the Ontario border this morning including Indian Bay (near Falcon Lake) at -31.5C and Rennie at -30C. Winnipeg airport got down to -24.2C. Airmass coming in this weekend through next week is about 10-15C colder! Yikes! That means lows in the mid -30s for Winnipeg likely (given Arctic ridge with clear skies and light winds) and a few -40C temps possible outside the city especially over eastern MB and Interlake regions.

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  2. Hi Rob, Accurate Weather is forecasting a snow storm on Jan 5,6,7.
    Any thoughts? I know it is a couple weeks away.

    Thanks

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    Replies
    1. Way too early to say.. any forecast of a particular weather event 2 weeks away is mere folly. The atmosphere is too chaotic and fast moving at this time of year to try to nail down a specific event 2 weeks from now. At this point, it's just another possible outcome.. but I wouldn't even consider it until there's more consistent signals a week away at the earliest. Honestly, I really don't look at model data more than 1 week away.. it changes too much after that to really have any faith in a particular scenario. At best, models can lean towards above or below normal temperature trends.. but that's about it.

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  3. One more day of normal temperatures for Winnipeg/srn MB Saturday before the big plunge moves in Saturday night into Sunday. Highs near -12C Saturday before Arctic cold front pushes in from the north Saturday afternoon, allowing that big mass of Arctic air to surge into southern MB later Saturday into Saturday night. Temps dropping to -26C by Sunday morning with highs topping around -19C Sunday afternoon. Winds should be light Sunday, but they pick up Christmas Day with NW winds of 30 km/h combining with temps near -25C to produce wind chills near -40. Very cold day. Cold temps continue through mid week with temps likely remaining below -20C until some brief moderation into the mid minus teens by late week.

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  4. High of -26.4C at Winnipeg yesterday.. makes it coldest Christmas Day max temp since 1996 and 8th coldest max for Xmas since 1872.

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  5. Snow snow snow please!!!

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  6. Any records near Rob. Its at this time of year i prefer the Farenheit Scale. Saturday looks so much warmer at a hi of 19 below aka -19F or -27C as the hi. Delivering newspapers as an 11 year old on sherbrook street in 55/56. Cold wasnt noticed until it went below -10F or -24C

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  7. Rob, is there any indication of an upward trend even to normal temps? Thanks

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    Replies
    1. Looks like we moderate to near normal next Tuesday, but then it gets cold again. Some signs of less cold temps developing here by second week of January.. but not a lot of consensus on that at the moment.

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  8. Typical 2 C cold bias with light NW flow at the official recording station this morning (12/30).. coming in at -35.5 C. Several surrounding Manitoba-ag stations (properly sited with open exposure) from rural areas were between -32.5 - -33.5 C.

    Please CMC, develop forecast points for the city or at least away from the airport. The forks station or Manitoba ag stations can be used for verification and development of MOS equations etc.

    Further, I propose the climate record be scanned and overnite lows adjusted for all cases with light NW flow for the period after which the station was moved away from the vicinity of the maintenance hangars (or where-ever it was in the 90's).

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