Wednesday, December 02, 2015

Mild November caps off 4th warmest fall on record at Winnipeg

Mild weather continued through much of November across southern MB, with mean monthly temperatures almost 4C above normal for November. In Winnipeg, November finished with an average monthly temperature of -1.0C or 3.9C above normal. This ties Nov 1928 as Winnipeg's 20 mildest November since 1872. Temperatures were especially mild over the first 3 weeks of the month before the first snowfall of the season on the 18-19th. Up until then, temperatures were above normal every day ending a streak of 25 straight days above normal since Oct 26th.     

Temperature anomaly map (left) for November 2015 shows core of abnormal warmth centered over northern Minnesota and southern MB in November. Only 4 days of the month were below normal in Winnipeg (right)  

The mild November helped cap off the 4th mildest fall in Winnipeg since 1872, tying the falls of 2009 and 1953 at 7.3C, or 3C above normal.

90 day graph of temperatures (right) in Winnipeg over the Sep-Nov period 2015. All 3 months were above normal, with only 19 days below normal over the 3 month period. 

Outlook for December: 

6-10 day CPC outlook
3-4 week outlook to Dec 25th

Milder than normal weather is expected to continue through at least the first half of December, thanks to a very strong El Nino this year. The next week looks especially mild, with an extended flow of Pacific air that will keep temperatures about 10-15C above normal into next week. Temperatures will be at or above the freezing mark over much of southern Manitoba over the next few days, especially in snowfree areas such as the Pembina valley (Morden, Winkler), SW Manitoba (Melita), downslope areas east of the Riding Mtns  (Dauphin, McCreary) and forested areas (Whiteshell)  In these areas temperatures may reach +5 to +10 C by the weekend.  Long range models are hinting at colder weather (near normal) arriving the weekend of Dec 12-13th, but it's too early to say if that's a trend to colder weather for the second half of December, or a passing cold snap. Past El Nino years suggest that cold snaps are usually short lived and not as intense as the upper pattern rebounds to bring a return of milder Pacific air over the country.  In fact, when looking at past strong El Nino years, there's a very high probability that December will end up warmer than normal in southern MB (as well as much of the northern and eastern US). The image below is a composite of average December temperature anomalies of 6 strong El Nino years since 1950 (1997, 1991, 1982, 1972, 1965, 1957)  Of these years, only one December was colder than normal in the Prairies (1972)  The top 2 warmest Decembers on record in Winnipeg occurred during strong El Nino events (1877 and 1997)  

Composite image of December temperature anomalies
based on 6 strong El Ninos since 1950


  1. We get into a nice westerly flow Thursday.. that will tap some of that warmer air to our west and should get Winnipeg above the freezing mark with afternoon temps climbing to +3C or so. Places like Morden and Dauphin could hit +7C.

  2. Amazing December warmth today across southwest Manitoba, especially in areas with downslope south-southwest winds off higher elevations. Morden hit a staggering 14.2C, not only the warmest spot in Manitoba, but all of Canada. Not very often Manitoba gets hot spot honours in December! It was a record for the date (prev 12.2C in 1916) and their 3rd warmest Dec temperature ever (behind 14.4C on Dec 1 1969, and an all time high of 17.8C on Dec 6 1939. Yes, 17.8C!) Many places in SW Manitoba hit double digits, including snowfee Brandon at 11C. Winnipeg and the RRV were robbed of the very mild temperatures, with a strong southerly wind up the mainly snow covered Red River valley keeping temperatures in the low single digits (high of only +2C in Winnipeg). The snowcover however is getting sparser by the day, and with a continuation of highs above freezing the next few days, the snowpack will gradually erode even more especially south and west of Winnipeg.

  3. Let's all enjoy while it lasts because it looking more like the snowfree ground or close to it will come to an abrupt end by next weekend. Models particularly the GFS have been hinting at a potential significant snow event by Friday into the weekend. Obviously we will continue to monitor this over the of course of the coming week but it's just something to keep in mind if you travel plans for next weekend.
    It is December after all.

    Rob, what are your thoughts on this potential?

    1. Yes, models are coming into good agreement that our extended December heat wave will be coming to an end by Friday this week, with a system coming in Thursday to bring about the change to colder weather. And by colder weather, I mean dropping to closer to normal which is now highs of -8 and lows of -18C. Just goes to show you how much above normal we are right now.

      There is still a lot of uncertainty however about how much snow we'll be seeing later this week into the weekend. We should see some snow with the Thursday system, possibly beginning as rain if temps are warm enough.. before another system tracks into Minnesota which threatens more significant snow over the weekend. But still a lot of uncertainty on the the track of that system varying from a miss to a more definite hit. Will have to wait to see more model consistency before I make any snowfall predictions.