Cool Nights Ahead, Otherwise Seasonal

We’ll see fairly seasonal weather over the weekend with overnight lows that will start off cool but climb back towards normal as well.

700mb Temperatures for Saturday Morning

700mb temperatures from the GEM-REG for Saturday morning. A significant pool of cold air remains entrenched over NW Ontario, while warm air builds over Alberta and struggles to push eastwards.

After quite a chilly evening last night, temperatures will climb nicely today towards a high of about 25°C. We’ll see mainly sunny skies today and clear skies tonight as we head down to a low of around 8°C. Tomorrow morning we’ll see some cloud as a weak disturbance travels south through the Interlake with a slight chance of a shower before things clear out midday and we’re left with sunny skies and a high a little cooler near 23°C as more cool air filters down behind the morning’s system. The weekend will close out with another sunny day with a high climbing a little bit higher into the mid-to-upper 20’s.

The next chance of precipitation looks to possibly be on Tuesday morning, however the risk is marginal and currently looks like the system will remain to the north of the Red River Valley.

2012 One of the Hottest Years on Record

We covered just how warm July 2012 was a couple posts ago, but what’s shaping up to be an even bigger story is just how hot 2012 as a year is. Last week, Jeff Masters covered how 2012 is shaping up to be the hottest year ever in the contiguous United States and included an image from NOAA that showed average yearly temperatures through the climate record, highlighting the top 5 and coldest 5 years on record:

Year-to-Date Temperature Anomolies for Contiguous U.S.

Year-to-date temperature anomaly, by month, for 2012 (red) compared to the other 117 years on record for the contiguous U.S., with the five warmest years (orange) and five coldest years (blue) noted.

With plenty of warm records having been broken over the past year, and the fact that we’re going on 13 consecutive months with above-normal temperatures, I thought it would be interesting to see what such a chart looks like for Winnipeg.


First I calculated the monthly mean temperatures for the entire climate archive for Winnipeg, which covers March 1872 – July 2012. I then calculated year-to-date normal temperatures for each month from 1901 to 2010 to use as a “20th Century Average”. For example, March’s YTD average was calculated simply by:

    March Average = AVERAGE(JAN Average + FEB Average + MAR Average)

To calculate the temperature anomolies, I did a similar process on the monthly mean temperatures for each year, calcluating a YTD value for each month, then simply subtracted that from the associated month’s 20th century average. This process produces the signature tapered look on the above chart, where the large variability from year-to-year evident in January smooths out to nice, clean lines by the end of the year.


The results for Winnipeg are startlingly similar to the United States:

Year-to-Date Temperature Anomolies for Winnipeg, MB

Year-to-date temperature anomaly, by month, for 2012 (red) compared to the other 139 years on record for Winnipeg, MB, with the five warmest years (orange) and five coldest years (blue) noted.

It’s quickly evident that 2012 is on track to end as one of the warmest years on record. The current top 5 warmest years are:

Rank Year Year-End Temperature
1 1987 +2.93°C
2 1931 +2.80°C
3 1878 +2.20°C
4 1998 +2.14°C
5 2006 +2.00°C

This year’s current YTD temperature anomaly is sitting at +3.13°C. This beats out 1987’s year-end anomaly of +2.93°C, however is less than the value calculated at the same time of year (July), which was +4.02°C. We’ve started August off right near-normal, however ensemble outlooks have us returning to slightly above-normal temperatures fairly soon.

A Record-Breaking Weekend on the Way

Winnipeg will see a record-breaking weekend ahead with potentially unprecedented heat on the way. 3 daily record high temperature records have already been broken this week, and at least another 3 will be broken over the next few days. In fact, there’s also a chance that we’ll see warmer weather by the beginning of next week than we’ve ever seen in March.

March has been nearly unprecedentedly warm this year, with temperatures quickly soaring 10-15°C above normal after a decidedly unpleasant snow storm started the month with more than 6” of snow in many locations. Plenty of uncertainty existed as to how warm it could get with so much snow on the ground, but extremely warm air aloft combined with light winds (and a few breezy days) have done an incredibly good job at eroding the snow pack over Southern Manitoba. The following slides show the quickly eroding snowpack over a mere 4 days:


  • 2012-03-11-morning

    Evening of March 11th


  • 2012-03-11-evening

    Evening of March 11th

  • 2012-03-12-evening

    Evening of March 12th

  • 2012-03-13-morning

    Morning of March 13th

  • 2012-03-13-evening

    Evening of March 13th

  • 2012-03-14-morning

    Morning of March 14th

  • 2012-03-14-evening

    Evening of March 14th

  • 2012-03-15-morning

    Morning of March 15th

Manitoba Snow Melt: March 11-15, 2012

  $(window).load(function() {
In a mere couple days almost all the snow disappeared from Southern Manitoba, quickly negating it’s potential to hold our temperatures back. As a result, we’ve broken several daily high temperature records this week, and are on track to break several more.

Day New
Record Year
Sun Mar. 11 12.8°C 12.5°C 1981
Mon Mar. 12 9.7°C 7.2°C 1922
Thurs Mar. 15 14.4°C 11.1°C 1927
Fri Mar. 16 19.9°C 12.4°C 1981
Sat Mar. 17 19.2°C 12.8°C 1938
Sun Mar. 18 ??.?°C 14.4°C 1910
Mon Mar. 19 ??.?°C 18.9°C 1938

So where’s this warmth coming from?

850mb Temperatures

850mb temperatures valid 00Z Saturday (Friday evening) from the GEM-REG.

As a long-wave trough approaches the west coast, a strengthening southerly flow will begin to advect plenty of heat and, surprisingly, moisture into the Northern Plains and Southern Manitoba. This will be enhanced by the record-shattering heat that’s been in place over the Central and Eastern US already, putting us within a stone’s throw of breaking another substantial record: the warmest day ever recorded in March in Winnipeg.

We’ll see exceptionally warm temperatures over the next few days:

  • Today: 22°C
  • Saturday: 18°C
  • Sunday: 21°
  • Monday: 25°C

These forecast highs will definitely put us in some of the hottest days ever in March in Winnipeg:

The top 3 hottest days ever recorded in Winnipeg in March are:

  1. March 27, 1946: 23.3°C
  2. March 23, 1910: 22.8°C
  3. March 28, 1938: 20.6°C

Monday will give us a decent shot at breaking the all-time hottest day ever in March in Winnipeg, but we’ll see how that goes a bit closer to the day. Today and Sunday will definitely find a place in that list, though.

And last but not least, there exists a chance for thunderstorms! Sunday night brings with it a chance of thunderstorms overnight. Several of the ingredients we look for to predict nocturnal thunderstorms are in place:

  • Moisture: Dewpoints at 850mb are progged to be ~ 15°C
  • Instability: Models vary, but we could see around 1000 J/kg of MLCAPE Sunday night.
  • Shear: We’ll have shear galore: 50-60kt of 0-500mb bulk shear
  • Trigger: An advancing warm front.

The cap may be a concern, and there may not be quite enough instability to get things going; there is certainly a non-zero chance though. We’ll keep updates on temperature records and the chance for thunderstorms in the comments as the weekend progresses!