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Climate Trends and Variations Bulletin

Winter Summary 2010/2011

This bulletin summarizes recent climate data and presents it in a historical context. It first examines the national temperature, and then highlights interesting regional temperature information.  Precipitation is examined in the same manner, first nationally, followed by the regional highlights.

National Temperature

The national average temperature for the winter of 2010/2011 was 2.5░C above normal, based on preliminary data, which makes this the 6th warmest winter since nationwide records began in 1948. The warmest was just last year, 3.9░C above normal, and at 3.2░C below normal 1971/1972 was the coolest. As the temperature departures map below shows most of the above normal temperatures happened in the northern half of the country. Temperatures were more than 4░C above normal for large areas of Nunavut, northern Quebec, and Labrador.  Areas over southern Alberta and Saskatchewan, as well as southern Ontario were below normal this winter.

Temperature Departures from Normal - Winter (Dec, Jan, Feb) 2010/2011

Temperature Departures from Normal Map - Winter 2010 - 2011

The temperature trend graph below shows that winter temperatures have been at or above normal since 1996/1997.  The red dashed linear trend line indicates winter temperatures have warmed over the last 64 years by 2.8░C.

The national temperature departures table shows the full list of winter values in the order from warmest to coolest, and shows that of the ten warmest winters, 4 have occurred within the last decade, and 11 of the last 20 years are listed among the 20 warmest.

Winter National Temperature departures and long-term trend, 1948 - 2011

Winter National Temperature Departures and Long-term trend chart, 1948 - 2011

Regional Temperature

There were four climate regions which ranked among the ten warmest winters.  They were: Arctic Mountains and Fiords region (Ranked 2nd, 5.3░C above normal); Arctic Tundra region (ranked 2nd, 4.6░C above normal); Atlantic Canada region (ranked 4th, 2.9░C above normal); and Northeastern Forest region (ranked 6th, 2.9░C above normal.  The Prairies region was the only region with slightly below normal conditions this winter (24th coolest, 0.2 below normal). A listing of all the regional temperatures departures and rankings are presented in the ranked regional temperatures table (MS Excel Version, 40 KB). Interestingly, the Mackenzie District has not had a cooler than normal winter since 1993/1994. The trends, extremes and current year rankings table shows that all of the eleven climate regions exhibit positive winter trends, with the Mackenzie District showing the greatest trend of 4.5░C over the 64 years of record. Atlantic Canada shows the least positive trend of 0.5░C over the same period.

Canadian Climate Regions Map

National Precipitation

As for precipitation, Canada experienced a near normal winter for 2010/11, 2.5% below normal, ranked as the 28th driest out of the 64-years of record. The wettest winter was 2004/2005, 18.3% above normal, and the driest year was 2009/2010, 22.4% below normal. The precipitation percent departure map below shows southern Alberta and Saskatchewan, Northwest Territories, Ontario and Labrador all experienced at least 20% less precipitation than average this winter. Northern Alberta, most of Nunavut, and the Maritimes experienced conditions that were at least 20% wetter than normal.

It should be noted that "normal" precipitation in northern Canada is generally much less than it is in southern Canada, and hence a percent departure in the north represents much less difference in actual precipitation than the same percentage in the south. The national precipitation rankings are therefore often skewed by the northern departures and do not represent rankings for the volume of water falling on the country.

Precipitation Departures from Normal - Winter (Dec, Jan, Feb) 2010/2011

Precipitation Departures from Normal Map - Winter 2009- 2011

The precipitation percent departures graph below shows that over the last ten years, six winters have been at or above normal. The national precipitation departures table presents the full list of annual precipitation values in order from wettest to driest. 

Winter National Precipitation Departures with Weighted Running Mean, 1948 - 2011
Winter National Precipitation Departures with Weighted Running Mean, 1948 - 2011

Regional Precipitation

The Arctic Mountains and Fiords (ranked 2nd wettest, 59% above normal), and Atlantic Canada (ranked 9th wettest, 14.1% above normal) both had top ten wettest rankings this winter. On the drier side of things, both the Mackenzie District (ranked 7th, 24.6% below normal) and the Great Lakes/St. Lawrence (9th wettest, 20.1% below normal) regions experienced conditions dry enough to rank among the ten driest winters. All of the climate regions and their rankings for the winter 2010/2011 relative to the last 64 winters are listed in the ranked regional precipitation table (MS Excel Version, 40 KB). Interestingly, South B.C. Mountains has only had one winter (2006/2007) with wetter than normal conditions over the last decade. A summary of this past winter’s precipitation rankings for each region, along with the record wettest and driest years, are listed in the extremes and current year rankings table.

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