Wednesday, 9 January 2013

#2 - Top Ten Weather Events of 2012 in the Winnipeg Area

The Winter That Never Was

     The winter of 2011/2012 was exceptional over almost all of North America. It defied seasonal forecasts that were made back in Fall 2010 which had predicted it to be one of the coldest winters in years. It was the absolute opposite. Instead, it was one of the most gentle winters in modern history.

Red River north of Winnipeg JANUARY 4. Pic by Madeleine Goodwin-Ominski/CBC Manitoba
     The seasonal forecasts were in large part based on the fact that it was a weak to moderate La Niña winter. These types of winters are known to be cold and snowy in southern Manitoba, but last winter was an anomaly. An unusually strongly positive AO (arctic oscillation) and NAO (north Atlantic oscillation) indexes through most of the winter overwhelmed the weather pattern over North America, greatly reducing the influence of La Niña. As a result of these positive indexes, the jet stream was stronger, blowing consistently from west to east. Thus, arctic air remained locked in the arctic and cold influxes towards the south were brief and uncommon. Also being further north than usual, the jet stream deflected storms to our north, explaining the minimal snowfall.

Emerson Christmas morning!
     The winter started off with the 9th mildest and 9th least snowy December on record in Winnipeg. The average mean temperature was -8.1°C; 5.4 degrees above the 1981-2010 normal of -13.5°C! The monthly snowfall total of 5.2 cm was just 22% of normal (1981-2010 normal is 24.1 cm). Thanks to the minimal snow and mild temperatures, it was a rare brown Christmas in parts of southwestern Manitoba and through the western and southern RRV with less than 2 cm of snow depth. Some areas didn't even have a snowflake on the ground! This was the first brown Christmas in southern Manitoba since 1997. Meanwhile, Winnipeg's snow depth was at 2 cm, which is considered a white Christmas. Since snow depth records began in 1955, only 7 Christmases in the city have had 3 cm or less on the ground.

     We were also greeted with record-warmth on Christmas day and Boxing Day with highs in the mid to high single digits.

     An incredible streak of warmer than normal days began on December 10, 2011. Following that day, temperatures were above normal everyday until January 11, 2012. This made it 33 consecutive warmer than normal days. Temperatures during this period averaged almost 10 degrees above normal! In addition, there were only 4 colder than normal days between November 21, 2011 and January 11, 2012 (a span of 48 days). Throughout the whole winter (December to February), there were only 18 colder than normal days (out of a possible 91 days).

     The streak of warmer than normal days saw a peak from January 4 to 10. This 7-day period featured temperatures that were at least 10 degrees above normal and in some cases as much as 20 degrees above normal thanks to a brisk Pacific flow of air from the southwest. Normal highs for the period are about -11°C and normal lows about -21°C or so. Instead, we experienced day after day of above zero highs and lows that were in the minus single digits. In fact, for 7 consecutive days the daily minimum temperatures were warmer than the normal daytime highs as we never dropped below -10°C. The average high during the period was about +3°C, or about 14 degrees above normal. Lows averaged about -6°C or about 15°C or 16°C above normal!

Winnipeg Jan 5, lots of grass!
     January 5 saw the peak of the warmth. Mostly sunny conditions, along with minimal snow cover and favourable downsloping winds from the west or southwest allowed for temperatures that were close to some all-time January highs. Winnipeg's high of 6.7°C easily broke the old daily record of 4.3°C in 1984, but was just 1.1°C shy of the all time January high of 7.8°C on January 23, 1942. However, it ties with January 22, 1942, for 3rd warmest January day on record. It likely could have been even warmer if we didn't have any snow on the ground. A couple centimetres of snow depth was probably enough to keep our temperatures a little lower. Areas of extreme southwestern Manitoba and in the western and southern RRV saw these warmer temperatures thanks to snow depth that was pretty much non-existent. The day in these areas started with temperatures that were already near 5 or 6°C at 8 AM. Temperatures then climbed into the double digits in the afternoon. Here are some records that were broken at Environment Canada weather stations outside of Winnipeg that day:

     A high of 12.7°C was also reported at the Pierson station southwest of Melita, but that station is for Manitoba Agriculture. Highs of 8°C and 9°C were reported as close to Winnipeg as Headingley, Sanford and Starbuck. 10°C readings were as close as Sperling and Elm Creek. The Forks reached 7.6°C and Charleswood reached 7.4°C.

     These highs did not break the all time January high for Manitoba. The warmest temperature ever recorded in Manitoba in January was 14.5°C in McCreary on January 7, 2003.

     Numerous all-time January highs were recorded in North Dakota. Fargo reached 13°C (old record 12°C), Minot 16°C (old 15°C), Williston 14°C (old 13°C) and Jamestown 13°C (tied).

Golf in Carman JANUARY 4! Pic by Dean North sent to TWN
     It was absolutely exceptional to have so much grass showing up in early January. The super warm day brought snow depth down to 1 or 2 cm in Winnipeg, but there were several bare spots with grass and mud visible. Some people took advantage of the snow-free ground in the western and southern RRV to do some golfing!!!

     A record high daily minimum of -5.2°C was also recorded that day. The following night (early January 6), a rare overnight rainfall fell over the city with about 1 mm recorded.

     More super warm days followed on January 9 and 10. Winnipeg reached between 4 and 5°C on both days. A high of 5.1°C on January 10 (which actually occured near midnight) tied the old record. Records were broken in other parts of southern Manitoba with highs in the mid to high single digits. It looked like April in Emerson on January 9 with sunny skies, a high of 7.5°C and not a snowflake on the ground.

     A cool down mid month was anything but the frigid temperatures that we come to expect in the winter, but it was almost unbearable after the incredible warmth to start the month. A zonal flow across North America kept the coldest arctic air in the arctic, and kept it brief. It didn't even get down to -30°C once in Winnipeg thanks to downsloping winds from the west on the coldest nights.

     Mild weather returned late in the month, ending January with an average mean temperature of -10.8°C; 5.6 degrees above normal and 3rd warmest January on record.

     We did not hit -30°C once in January, something that has only happened 3 times since 1873 (1931, 1944 and 2001). In addition, there were 8 days with above zero temperatures, tying with 1944 for second most days on record for the month (record is 14 days in 1942). Snow depth remained at or below 10 cm everyday up to the 31st. Normal is closer to 15 to 20 cm. A depth of 3 cm of January 1 was tied for 3rd lowest on record for the day, and a depth of 11 cm on January 31 tied for 8th lowest.
Near Neepawa FEBRUARY 21!! By Dean Robinson to TWN

     February defeated the odds by continuing to be mild and calm for the first half of the month. Remarkably, parts of southwestern Manitoba, the western and southern RRV and southern and western North Dakota remained nearly snow-free during this first half, and even for part of the second half. In Winnipeg, snow depth was still only about 6 or 7 cm on February 13, 3rd lowest for the day since 1955.

     February 5 featured the peak of the warmth through the month with temperatures once again reaching over 15 degrees above normal. Abundant sunshine and a westerly downslope wind helped temperatures rise into the mid to high single digits. A high of 6.8°C was reached in Winnipeg, just shy of the old record of 7.2°C in 1963. Highs attaining 7 to 9°C were common west and southwest of the city, with a maximum of 9.9°C in McCreary. Surprisingly, only 3 records were broken across southern Manitoba (Melita 6.3°C, Pilot Mound 8.8°C and Fisher Branch 5.6°C).
February 1 Winnipeg. Pic by Barb Johnson to TWN
      It wasn't until the second half of the month that things finally changed. A potent snowfall on February 20/21 marked the ''unofficial start to winter'' in Winnipeg and southeastern Manitoba with 2 to 10 cm in Winnipeg and 10 to 20 cm in southeastern Manitoba and the southern RRV. And the two week-long winter began. Several snow storms during the last week of the month into the first week of March dumped in excess of 25 cm of snowfall over Winnipeg and over 40 cm southeast of the city. The storm of March 1/2 was particularly potent with about 10-20 cm of snow across the RRV along with strong winds and lots of blowing snow. Travel disruptions were numerous with many collisions and highway closures. A warmup in March put an end to what will be known as the 2-week long winter, with all the new snow melted less than 2 weeks later.

     In the end, it was the 4th mildest winter on record in Winnipeg since these records began in 1873 (winter is considered December to February). The average mean temperature for the three month period was -9.7°C; 4.8 degrees above the 1981-2010 normal of -14.5°C!

     The winter minimum was a measly -28.9°C. This is the first time that the airport has not hit -30°C in the winter since records began there in 1938. It is also only the second time that the city has not hit -30°C since the winter of 1872/1873 (I make the difference because prior to 1938 temperatures were taken near downtown and not at the airport). This was in the winter of 1930/1931, when the winter minimum was just -29.4°C. That also makes winter 2011/2012's minimum of -28.9°C the warmest winter minimum on record. How can we be called Winterpeg if we can't hit -30°C even once?   :)

     In total there were 20 days with temperatures above zero from December to February, more than the normal of about 10 days. However, this Winnipeg value was meager in comparison to communities in the western and southern RRV. For instance, Morden had 41 above zero days (out of a possible 91 days).

     As mentioned previously, up to mid February snowfall was minimal. Only just over 25 cm fell from December 1 to February 14. Most of these snowfalls were minor with less than 5 cm. This along with the mild temperatures and sunny skies explained why snow depth was so minimal or non-existent in southern Manitoba through most of the winter. Including late February, there was 44.2 cm of snowfall through the whole winter; 72% of normal.

     The warmth caused some rare occurrences.

     Allergies had actually become a problem in January for allergy-sufferers thanks to the constant freeze-thaw cycle, the lack of snow cover and the unusually warm temperatures.

     City crews were filling potholes in January, something that is extremely rare. The pothole season does not usually begin until late February or early March. This was thanks to the freeze-thaw cycle as temperatures were near zero at day and below zero at night.

     As expeceted, the warmth and lack of snow through the winter also hurt winter businesses. Snow removal businesses were hauling only a fraction of the snow they normally would. Some winter clothing businesses reported a drop of 50% of their sales. Snowmobile sales were down as snowmobile trails were closed across most of the province. And for skaters, skating rinks such as at The Forks, Assiniboine Park and on the Assiniboine River were forced to shut down on many days due to significant melting. In fact, many rivers had a lot of open water well into the winter. The Red River had sections of open water here and there throughout January and in February. Any ice present was extremely thin.

Jan 26. By Laurette Fellows to TWN
     A few trees even began to bud in January on some of the warmest days. This is not unheard of, but is certainly a sign that it was way warmer than it should have been.

     In early January, a health emergency was declared in Berens River, on the eastern shore of Lake Winnipeg. Impassable winter roads were preventing supplies from reaching the community, and the community had run out of gasoline. Health workers could not reach patients who needed regular care as a result.

     There were a few advantages. The spring flood was much less significant thanks to the minimal snowfall as well as the dry soils. The warm weather also brought people outside more instead of being cooped up inside all winter.

     The winter of 2011/2012 was just as unusual across most of Canada and the United States. Across Canada, winter (Dec to Feb) was 3.6°C above normal and 3rd warmest winter since these records began in 1948. It was also the second driest. Here in the Prairies more specifically, it was the 3rd warmest as well as the driest. The warm weather was thanked for causing huge energy savings as well as saving governments money on snow clearing.

     In Toronto, it was the warmest winter ever since records there began in 1840. With 41.8 cm of snow it was also the least-snowiest. There was no measurable snowfall after March 1. In Montreal, the mercury never dipped below -20°C, the first time ever. Across Alberta and Saskatchewan, grass fires occured instead of snowfall. The ground was bare across much of southern Saskatchewan and Alberta well into January. Strong chinook winds brought temperatures exceeding 10°C in southwestern Saskatchewan and through much of Alberta on January 4 and 9. On the 4th, it reached as high as 16.4°C in Maple Creek, Saskatchewan, breaking its old record by about 5-6°C. Similarly, in Alberta temperatures reached 15.3°C in Calgary, and almost all of southern and central Alberta reached double digits. However, the chinook winds that day brought incredible gusts over 110 km/h in southern Alberta causing lots of damage. In addition, some sections of rivers in Saskatchewan were virtually ice-free into February.

Qu'appelle River near Craven in Saskatchewan FEBRUARY 19. By Stew Fettes to TWN
     South of the border, people were golfing instead of skiing throughout the winter. For the contiguous US it was the 3rd least snowy January on record since these records began in 1967. 95% of the country that normally had snow in early January had below-normal snow-cover at that time. The northern Plains had an incredible lack of snowfall with virtually bare ground well into January.

     In January, flowers were sprouting in New Hampshire, cherry trees were budding in Washington DC, peach trees were budding in Georgia and in Oklahoma daffodils were blooming. In Nebraska, temperatures reached the high teens in early January, more than 15°C above normal in some cases. And in Washington DC, temperatures were near 20°C late month.

     Lastly, in Fargo it was the warmest winter ever with an average mean temperature of -5.5°C.

This post contains information, photos or video from the following sources:

Environment Canada Weatheroffice & top 10 weather events of 2012
CBC Manitoba
CTV Winnipeg
The Weather Network
Jeff Master's WunderBlog
Emerson Webcam
Rob's Blog
CBS News
Google Maps
NWS Grand Forks

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