El Niño to impact Canadian winter, here's what it brings
Wednesday, January 27, 2016, 10:01 AM - Winter will be milder than normal across much of Canada. This rings especially true for Canadians living across the Prairies and into northern Ontario. Read on for full analysis of every Canadian province and territory.
For those Canadians living in southern Ontario to Atlantic Canada, it will be considerably milder than the past two winters.
That said; this region is not off the hook overall. We expect an extended period of classic winter during the second half of the season, which should result in near normal for the winter as a whole as depicted in the temperature map below (scroll down for precipitation forecast).
WINTER FORECAST: Here's everything you need to make it through the coming season
Full Winter 2015/16 forecast
While winter officially begins near midnight on December 21, 2015, (December 22, 2015, for Atlantic Canada), our winter forecast is for the months of December, January and February.
For December, we expect that a mild temperature pattern will dominate most of Canada from British Columbia to the Maritimes as the jet stream pattern will allow Pacific air rather than arctic air to flood across the country. The one exception to this will be northern Quebec, Labrador and most of Newfoundland where temperatures will be near to below seasonal.
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However, a change in the pattern is expected for the second half of winter, especially during February. While above seasonal temperatures will continue to dominate the pattern for the western half of Canada, an extended period of classic winter weather is expected from Ontario to the Maritimes as near to below seasonal temperatures will dominate the pattern.
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Above seasonal temperatures can still be accompanied by heavy snowfall, but during the upcoming winter we expect below average snowfall from Alberta to Northern Ontario. In contrast, an active storm track across the southern United States will turn up the east coast of the U.S. and bring above normal precipitation to the Maritimes.
Much of the west coast of British Columbia will also see above normal precipitation (see the B.C. section below for more).
Forecasting months in advance
It is important to keep in mind that a seasonal forecast is designed to provide an overview of the season as a whole, and it cannot describe each day of that season. Even the mildest of winters will have periods of cold weather with the potential for memorable winter weather events. For example, the devastating ice storm of January 1998 across eastern Ontario and southern Quebec happened in the midst of a mild winter.
Here is a regional breakdown of what our winter forecast means for your part of Canada.
Newfoundland & Labrador
Near normal temperatures are expected for the winter as a whole, though we think that the final numbers are more likely to be slightly above rather than below normal. Newfoundland and Labrador typically see an abundance of active weather during the winter and this year should be no exception. However, at times the storm track will be too far offshore to have a major impact on the region, so final precipitation totals are expected to be near seasonal rather than above seasonal.
This winter will be considerably milder and less snowy than last winter, but the Maritimes will see some of the coldest and messiest weather (relative to normal) in Canada. The winter will start off relatively mild, but we expect a period of classic winter weather during the second of winter, especially during February. An active storm track up the east coast of the U.S. will impact the Maritimes for most of the winter. However, we do not expect snowfall totals to compare with last winter as a milder pattern will result in more storms that bring a variety of precipitation types (snow, ice and rain) to the region.
Southern Ontario & southern Quebec
December will be quite mild across this region, but a more classic winter pattern is expected to dominate the second half of winter, especially during February. However, we do not expect the cold to become as severe or as persistent as it was during the past two winters.
The precipitation pattern for this region is quite challenging as we expect areas of above normal and below normal precipitation to be relatively close to each other in this region. An active storm track up the east coast of the US will typically just miss this region. However, if this storm track is shifted slightly to the north and west, then eastern Ontario and southern Quebec, especially the Eastern Townships, would see above average snowfall.
Areas further to the northwest are expected to miss most of the major storms and receive fewer than normal Alberta Clippers. However, we do expect that a few systems will be outside of the typical storm track and these systems have a heightened potential to be rather moisture laden. Therefore, much of the region should still see near normal precipitation despite fewer than normal storms.
The milder temperature pattern for the Great Lakes will result in less lake ice than the past two winters and fewer than normal lake effect snow events. However, there is still the potential for a few significant lake effect snow events since the lakes should be relatively warm and ice free when arctic air does reach this region.
Prairies and northern Ontario
Above average temperatures and below average snowfall are expected across this region. During December the entire region will see above to well above seasonal temperature, but during the second half of winter (especially February), the focus of the warmest weather relative to normal should be focused across the western Prairies while Manitoba and northern Ontario will see more classic winter weather at times.
While the winter will feature above seasonal temperatures, the pattern will break down at times and it is important to keep in mind that impactful weather can occur even with temperatures that are several degrees above seasonal.
While below normal snowfall may be good news for travel and reduces flood concerns in the spring, a lack of winter snow would raises concerns about soil moisture levels when the growing season starts in the spring.
Above seasonal temperatures are expected for British Columbia, though they are not expected to be as mild as they will be for the western Prairies. Wetter than normal weather is expected for much of the west coast. However, there is more uncertainty when it comes to the south coast of B.C., especially around Vancouver and southern Vancouver Island.
The dominant storm tracks should be north and well south of this region. However, while this should result in fewer than normal rainy days, at times the “Pineapple Express” will bring a few rounds of heavy rainfall that will bring precipitation totals for the season that are near to above average for the season. Further inland, precipitation totals will drop off to near normal and even below normal for southeastern B.C.
While the anticipated pattern for the winter as a whole is not ideal for skiers, it is a lot more favourable than what we saw last year. This season is already off to a much better start and the pattern for early December looks favourable for further building up of early season bases at most resorts which is great news as we head towards the Holidays.
Yukon, Nunavut and Northwest Territories
Above normal temperatures are expected to dominate much of the Yukon and Northwest Territories, especially across the south, including Whitehorse and Yellowknife. Near normal temperatures are expected for Nunavut. Near normal precipitation is expected for most of the region, though above normal precipitation is expected for parts of the Yukon, including Whitehorse, and for southern Nunavut near Hudson’s Bay.
How long will winter linger?
To be honest, I have reservations about issuing a forecast for a single month (March) this far in advance. However, there are times when the global pattern lends itself to having higher confidence in months that are further away. For example, it looks like our December forecast that was issued in August will work out very well (actually better than our forecast for November).
El Niño years do not have a reputation for early springs. Given the pattern that we expect for February and my recollection of other El Niño years in which spring was delayed, I was expecting that we would have a cold forecast for March from the Prairies to Atlantic Canada.
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However, as much different pattern emerges when we look more carefully at years in the past in which El Niño was rapidly fading and had a similar global patterns to what we anticipate for late winter. While there are some exceptions, most years with that pattern turned rather mild during March. So, while the cold weather from February may linger into early March, we should see spring weather start to arrive on schedule or possibly even earlier than normal across much of Canada.
Forecast rationale: What is El Niño?
El Niño has a reputation of bringing mild winters across southern Canada, and we are currently in the midst of one of the strongest El Niño events on record. So, why are we not forecasting a mild winter across all of Southern Canada? To explain, we first need an explanation of El Niño.
El Niño is associated with warmer than normal sea surface temperatures in the Pacific Ocean near the Equator, to the west of South America. The map below shows the current ocean water temperatures relative to normal during the final week of November. The various shades of yellow, orange, and red represent warmer than normal ocean water temperatures. The circled area is the region that we focus on when talking about El Niño and in this region water temperatures are running up to 3°C warmer than normal.
This is the signature of a very strong El Niño. However, during the two strongest El Niño events of the past (1982-83 & 1997-98), the warmest water was right next to the coast of South America. This year the warmest water is shifted to the west and during the winter we expect that will continue to shift further to the west. A look back through history shows that when the warmest water relative to normal is closer to the central Pacific rather than next to South America, the impact on Canadian winters is different, especially for eastern Canada.
To further illustrate this, the two maps below show a comparison of the fall of 1997 versus the fall of 2015. On the top map, you can see that the warmest water in 1997 was immediately to the west of South America, while the bottom map shows that the warmest water is shifted to the west.
A unique feature of this year’s El Niño is the warmer than normal ocean water temperatures that are widespread throughout the North Pacific (to the west of Canada and the United States). This resembles the pattern that we saw during the past two years which was associated with frigid winters across most of the eastern half of Canada. In addition, we can also see that the sea surface temperature pattern across the Atlantic Ocean is the reverse of what we saw in 1997-98.
Another key to upcoming winter is that it appears that El Niño is peaking as we head into winter and that it will steadily weaken during winter. During the winter of 1997-98, El Niño remained very strong through the winter. A weakening El Niño has a different impact on our weather pattern than does a strengthening El Niño. However, if El Niño surprises us and continues to strengthen, then the mild temperatures would likely be persistent through more of the winter.
While the strength of this year’s El Niño is comparable to 1997-98, the numerous differences in the global pattern outlined above (and a few other factors beyond the scope of this article), are why we do not expect a repeat of the mild winter across all of Southern Canada. The pattern into mid-December will be quite mild across all of Southern Canada, but we expect that winter will arrive eventually, especially from Southern Ontario to the Maritimes.
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