Monday, January 23, 2017

January thaw melts records in Winnipeg

It was a record breaking mild weekend in Winnipeg as an unprecedented stretch of above freezing temperatures turned ice rinks and streets into puddles and slush across the city. The temperature at Winnipeg airport (where official temperatures are measured) rose above freezing at 4 am Friday morning Jan 20th, and stayed above freezing until 11 pm Sunday evening Jan 22nd. The stretch of 67 straight hours above freezing set a new record for the longest January thaw on record in Winnipeg, eclipsing the old mark of 44 straight hours Jan 8-9th 2002.     


Hourly temperature records for Winnipeg airport go back to 1953, but even looking at daily records shows that the 67 hour thaw is likely the longest such stretch in January in Winnipeg since records began in 1873. The only other comparable January thaw* would have been Jan 9 - 12 1928 when the temperature failed to drop below -1.6C over the 4 day period. However even then, there wasn't a 48 hour period where the temperature was consistently above 0C, so it appears this most recent warm spell is the longest such streak for January in Winnipeg in 144 years of weather records.  (*NOTE: "January thaw" in this case is defined by consecutive hourly temperatures of 0.0C or more. There have been longer stretches in January where daily high temperatures have reached 0.0C or higher, but temperatures dropped below freezing at night. The longest stretch with daily highs of 0.0C or more in Winnipeg in January was 9 straight days in January 1942 from the 16-24th, with 14 in total during the month, including Winnipeg's all time January high of +7.8C on the 23rd)  

The 3 day thaw also set new daily record high minimum temperatures in Winnipeg from Jan 20 to 22nd inclusive:

Record daily minimum temperatures set Jan 20-22 2017
(table courtesy of @jjcwpg)
Normal lows for this time of year are near -23C, so these temperatures are almost 25C above normal lows! The low of +0.9C on Jan 21st was only the third time in 144 years where the temperature did not drop below freezing during a January day in Winnipeg. The only other dates were Jan 12 1928 (minimum of +1.1C), and Jan 14 1894 (minimum of 0.0C).  Thus, a 67 hour streak of above freezing temperatures in January in Winnipeg is an exceedingly rare occurrence. Note also that 2.9 mm of rain fell on Jan 20th, the 2nd highest rainfall for any January day or month since 1873 (second only to the 3.8 mm that fell on Jan 20 1944) The mild weather, although welcome after a frigid first half of January, forced the closure of city rinks and skating trails as ice melted into slush and giant puddles. The thaw also resulted in locally slippery streets and walkways as water slicked up packed snow and ice.   

Temperatures are slowly cooling off this week to below freezing, but will remain above normal values the rest of the week before more seasonable temperatures return by the weekend.   

26 comments:

  1. According to EC, 1.7 mm of precipitation fell yesterday (the 22nd). Was that all in the form of rain or was the precipitation mixed? If it was all rain, that would set a daily rainfall record for the day and also push the overall rainfall amount to above the record amount set in 1944.

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    1. It was mixed with snow. We're estimating about 0.4 mm of that amount was rain. Unfortunately, the precip total from EC's automated gauge doesn't distinguish rain from snow (only shows total "melted precip") so we have to use an "estimated" amount for the rain total. Using 0.4 mm, that would put our January rain total to 3.5 mm, just shy of the 1944 record.

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  2. Rob Excellent summary of of our best Bonspiel thaw in history. It also confirms Chris Burt Weather Extreme (see above right for link) November Blog reporting on higher continental minimum records affect of Climate warming . Interesting that his blog also mentions the lack of Canadian Records Data especially onSouthern Manitoba and Saskatchewan . Perhaps you or Julien can enlighten him.

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  3. From Chris Burt's Blog NOV 21,2016
    "It is frustrating that I am unable to find what Canada’s record for this might be. Toronto’s record is 26.6°C (79.9°F) on July 21, 2011, but it is likely other locations (probably many) have seen warmer lows elsewhere in the country, especially in southern Saskatchewan and Manitoba during the intense summer heat waves of the 1930s (Bismarck, North Dakota had a minimum of 83°F/28.3°C in July 1936). Hopefully, one of the readers of this blog knows the answer."

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    1. Interesting. He's probably looking only at Winnipeg airport records which only go back to 1938. Winnipeg has good climate data all the way back to 1872 when daily records began at St John's College downtown. By the way, Winnipeg's warmest nighttime low is the same as Bismarck's, 28.3C (83F) during the same 1936 heat wave (July 12 1936). I'll let him know..

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    2. I saw a comment on that blog post of someone saying there was a low of 32C (90F) during the heat wave of July 1937 somewhere in southern Alberta or southern Saskatchewan. They didn't mention exactly where.

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    3. JJ... That low of 32.2C was reported from Aneroid SK for July 5 1937, with a high of 41C that day.. the same day that Canada's hottest temperature on record (45C) was recorded in Midale and Yellow Grass SK.

      However the reading no longer appears in the climate database (at least online). The reading is erroneous, since the next day's high in Aneroid was also 32C. In addition, the low on July 5th in nearby Cadillac and Gravelbourg was 18C, and no other SK site had a low higher than 24C that day.. so there is no way that Aneroid had a low of 32C. It most certainly is erroneous.

      Which begs the question.. what is the actual highest minimum temperature ever recorded in Canada? Winnipeg had 28.3C on July 12 1936 which ranks right up there.. but I don't know what the actual highest in Canada is. I'd have to investigate further.

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    4. I couldn't find that low either so I was a little suspicious. Thanks for finding that Rob.

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    5. Looks like Melita MB had a low of 31.1C on July 12 1936 (same day as Winnipeg's 28.3C low) which is the highest I could find. But that low also looks suspiciously high for the area that day.. lows in SW MB were generally in the 20-23C range.. and Melita lows were generally in the 15-20C range during that entire 1936 heat wave. So 31C seems suspiciously high. But, they had highs around 40C during that time, and Winnipeg had a low of 28C... so I can't completely discount it.

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    6. Any chance of instrumentation freeze from the previous days heat in those two locales?

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    7. Jim.. Readings back then were taken by weather observers using good old fashioned mercury filled thermometers. Any error would have been from reading the thermometer wrong, or entering the wrong value.

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  4. Rob what are your thoughts on Monday snow?

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  5. Rob what are your thoughts on Monday snow?

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  6. Hey Rob, further to the question about Monday snow. How does WN say 5-10 and EC say sunny and only 30% of flurries? Like come on. How two days out can they be opposite? Hell I could be a meteorologist.

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    1. Jeff.. certainly is a discrepancy, but that's not a meteorologist spitting out those forecasts, it's a computer. Weather forecasts from EC after today and tomorrow are automated, and come from model output. Weather Network does much the same. The discrepancy likely arises from the fact that TWN uses different models for their long range forecasts, whereas EC uses output from only one model, the Canadian GDPS. That could lead to very different forecasts even 2 or 3 days out.

      As far as Monday is concerned, we have a clipper system tracking through the Interlake with a trailing cold front coming through Winnipeg and the RRV by late afternoon/evening. I'm thinking the bulk of the snow with this system will be mainly through the Interlake on Monday (perhaps 5-10 cm), with maybe 2-4 cm for Winnipeg and a dusting for the southern RRV. Then we may get another couple cm with the cold front Monday evening. So for Winnipeg, I think that 30% chance of flurries is underdone, but 5-10 cm seems overdone.

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  7. Thanks for the explanation.

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  8. Well, now EC is calling 5-10 cm for Winnipeg Monday while TWN is going with around 5. Latest guidance is showing clipper will track from The Pas through the southern Interlake to Sprague area by afternoon. Snow should spread into Winnipeg overnight tonight with 2-4 cm by mid morning, then a bit of a break before snow redevelops in the afternoon thru evening with another 5 cm or so possible by Tuesday morning. So 5-10 cm for Winnipeg is possible although it will be a prolonged event. Guidance suggests heaviest amounts of 10-15 cm possible mainly east of the RRV over Steinbach, Whiteshell, Sprague regions by Tuesday. Light snow could linger into Tuesday as trough hangs back over southern MB, so that "sunny" forecast Tuesday might be a bit optimistic.

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  9. Rob, I've been hearing that it appears we will be trending colder for February here in Southern Manitoba.

    What are your thoughts on this.

    Thanks.

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    1. Yes, it does look like we'll be getting colder for the beginning of February after this next clipper system tracks through Monday into Monday night. Temperatures will be a bit below normal the rest of the week into next week, but at this point, it doesn't look as cold as the first half of January was.

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  10. It is hard to believe that in just over a month we will be back to dates which have record highs near or exceeding +20C. It feels like winter just started 7 or 8 weeks ag😎

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  11. Rob twitter is to short for this
    ‪@EmilyTWN @robsobs I had left this area by 77 but i remember how quickly those storms spun up and off the lakes and a meter or two of snow could come out of nowhere in a few hours. Resembles pics of the 66 blizzard In the peg.
    Do you remember if the drifts were as hard as pavement or did you sink into them when walking over. Great story

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    1. Don.. The Blizzard of '77 in Niagara was one for the ages down there. 4 days of howling winds blowing deep snow off Lake Erie into huge drifts. Didn't get a lot of new snow during the storm.. just wind blown snow off Lake Erie. And yes, the winds were so strong and lasted so long, that snow drifts were compacted like concrete. Drifts easily supported weight of people or animals over fences, houses, even hydro lines! Quite the memorable storm..

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  12. Hey just wondering rob. What is the snowpack at now after the melt? I know it was about 50cm before the melt but I'm wondering what it is now?

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    1. 37 cm snowdepth at my location as of this morning. My snowfall/precip data is updated daily at..

      http://climate.weather.gc.ca/climate_data/daily_data_e.html?StationID=43185

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  13. Rob, it looks like models are hinting at a warmup by February 11th or so. Does this look another potential extended period of above normal Temps again or just a brief warmup? Thanks.

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    1. Anonymous.. It looks like we'll be trending towards above normal temperatures for the second half of February. There may be an occasional dip in temperatures, but overall, long range guidance is indicating above normal temperatures over much of western Canada for the latter half of February. Latest CPC outlook supports this idea.

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