Sunday, December 06, 2015

December warm spell continues - but trend to colder weather and snow by end of week

It was another balmy day across southern Manitoba Sunday, with temperatures once again well above normal for December.  Snowfree areas and localities in downslope regions were the warmest again as temperatures soared into the double digits yet again, including 11C in Winkler, 10C in Morden and 11C in Wawanesa. In these areas, daytime highs have been above freezing for a full week now, including 2 or 3 days in the double digits.  

Winnipeg didn't fare quite as warm Sunday with southerly winds off a lingering but diminishing snowpack over the northern and eastern Red River valley keeping temperatures in the low single digits (high of +3C) Nonetheless, considering normal highs are now -7C and lows near -18C, few people will complain about temperatures some 10-15C above normal (except cold weather and snow lovers)   But if you're looking forward to colder weather or snow, there's some good news in the forecast. Models are indicating an end to the current December warm spell later this week, with a return to more seasonal temperatures by the weekend. Before that, a weak system tracking across southern MB Tuesday may bring some mixed precipitation (including a threat of freezing rain) Tuesday.  A stronger system will impact southern MB by Thursday with some snow possible which will herald the arrival of colder air later Thursday and Friday into the weekend. There is a possibility of more snow on the weekend, but models are less certain about the timing and amounts.. so that will need to be monitored. In any case, enjoy the balmy weather while you can.. colder weather and snow is on the way for the end of the week.

14 comments:

  1. It certainly appears more and more likely that our amazing December warm spell will come to an end later this week as temps will return towards normal and even at that, that's still pretty good considering what it can be at this time of year. The good news in all of this, it appears less likely for a snow event now on the weekend than it did a couple of days ago so hopefully that continues to be the trend however some snow is still possible this week particularly Thursday but may even be rain as well depending on temps.

    That just shows just how much above normal we've been and how impressive this warm spell has been. it's unfortunate however that we here in Winnipeg have not had the opportunity to fully benefit the extent of this warm spell like most areas in Southern MB have but nonetheless anytime we are talking about plus temps in December, it's significant.

    For whatever reason it seems like Winnipeg had received more snow that anyone else especially south and west of here where most if not all of these areas have no snow now hence the reason for the much warmer temps there.

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  2. It's interesting to see the impact (or lack thereof) of roughly +3 temperatures and sunshine in Winnipeg for several hours each of the past few afternoons. We've even gone over 24 hours with temperatures hovering above freezing.

    While some melting has occurred, with the sun being low in the sky, we don't seem to experience the same degree of melting that we would with +3 temperatures and sunny skies for several hours a day in say, mid-March.

    At any above freezing temperature, with the degree of cloud cover a constant, is there any way of quantifying the effect of the angle of the sun on its capacity to contribute to snow melt?

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    1. Looking at sun tables for Winnipeg, the maximum sun angle above the horizon right now is only 18 degrees at solar noon, which means the sun is bascially bouncing off the snowcover with little power to melt it. In comparison, the maximum sun angle in mid March is 38 degrees which is over twice the sun angle right now. So it has much more power to melt snow compared to the sun now. In addition, we only have just over 8 hours of maximum sunlight right now, compared to almost 12 hours in mid March. So not only is the sun stronger in March, it can also be out much longer.

      I too have been surprised how little snow has melted so far at least here in Winnipeg. My snow cover has barely budged over the past 4 days with afternoon temperatures above freezing. However I noticed on satellite imagery today that snow cover has become very patchy southwest of the perimeter. That should help us get a little warmer over the next couple of days if we can get a southwest wind here, which would also help bring down our snowcover.

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    2. Thanks for that info. It's remarkable how much of a factor those angle differences are. I suppose we Winnipegers never really think about it because it's almost unheard of for us to have so many consecutive above zero days at this time of year, and so we've never had an opportunity to notice.

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  3. 4.7C at the airport as of 2 pm today! Will Winnipeg break that temperature record? 0.5C to go!

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  4. It looks like the record was broken. It was 5.2C at the airport for 3 pm. It's certainly a tame and unexciting temperature record relative to Morden's last week, but at least the records will show that this December heat wave mattered to Winnipeg as well.

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    1. Yes it was.. 5.6C at YWG airport beats previous record high for Dec 9th of 5.1C back in 1990. Kind of a soft record as most our record highs around this time are still in the +7-9C range. But I agree, nice for Winnipeg to set a record during this warm spell which will be ending today!

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  5. Messy weather on the way overnight into Thursday.. Precip could start as some freezing rain overnight before changing to snow by morning rush hour. Temperatures will still be mild enough that the morning rush will only be wet.. but as the day wears on, increasing north winds and falling snow plus temperatures dropping in the minus 3 to minus 5 range could make for a tricky commute home.. especially outside the perimeter.

    Had to come sooner or later!

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  6. I see Woodlands is down again and because of the poor overlap, missing a chunk of the composite picture right over the City of Winnipeg. When asked, EC said that they only expect their sites to have a 95% uptime which seems low for critical infrastructure. In addition they don't seem to post any outage information anywhere, unlike south of the border where I've seen estimated repair times shown when their sites fail. They said the 5 year average for Woodlands was 97.4% so I imagine it isn't on any priority list for an upgrade.

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  7. Hi Rob,

    I see that EC as of 11 am is still calling for 2-4 cms today.
    With the radar down it is hard to see when this will start and end.
    I'm in the snow business and without the radar it kind of sucks.

    Do you think this will happen? WN says 1 cm.
    If the radar was up I would have a better idea myself.

    Thx,

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  8. Sorry for the delay in replying..

    As for Woodlands radar, it is currently down for a major hardware upgrade, mainly to upgrade key components to maintain its lifespan. EC has posted a radar outage message on the Woodlands radar site, which points to this link..

    http://www.ec.gc.ca/meteo-weather/default.asp?lang=En&n=67BC9FEB-1

    Expected to be back in operation by next Friday Dec 18th.

    As for out snow amounts, Winnipeg missed out on the heaviest band which tracked from the Riding Mountain area through Neepawa (10-15 cm) into Portage LP and the southern RRV (5 cm or so). Winnipeg ended up with a couple cm which mostly melted today. We could still see a dusting tonight.. but the bulk of the snow has moved off.

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    1. Didn't notice the outage link on the Woodlands site. Thanks for pointing it out Rob

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  9. Hi

    Does Wednesday and Thursday looks like significant snow?

    Thanks

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    1. Been watching that.. main storm system will be tracking through Minnesota, but still uncertainty about how far west storm will track which will determine impact on southern Manitoba. Even a difference of 50 miles in the track could mean the difference between a dusting and 15 cm. At this time, the ECMWF (the first model to catch onto this system impacting southern MB) is giving about 5-10 cm for Winnipeg/RRV, but again.. still too early to pinpoint amounts at this early stage given track uncertainty. But something to keep an eye on and I will be updating my blog later today on this system.. stay tuned.

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