2017-2018 Winter in Review - Snow (so far)

Today we are going to continue our 2017-2018 Winter in Review (even though the winter isn't quite over yet...). Previously we've looked at:

• 2017-2018 Winter in Review - Temperatures
• 2017-2018 Winter in Review - The Really Cold Days
• And if you are curious about last year the 2016-2017 write-up is here.

The focus for today will be the snow that we've received so far this winter (and there will be many, many charts), but first things first:

This chart shows the likelihood of snow during each month of the year at the International Airport. It's animated, and so it switches between the chances of any snowfall (0.1cm or more) and the chances of a notable snowfall (1cm or more).

And the unfortunate truth is that the chances of us having seen our last snow for the winter are basically 0. Even in warm years, April gets a 1cm snowfall more than 90% of the time, and during May it's 55% of the time. But we are at the point where new snow shouldn't really stick around.

So lets take a look at the snow so far...

Snowdepth

This chart shows the history of snowdepth at the International Airport on March 31.

This year we are at 31cm, which is the 6th highest since records began at the International in 1961. In terms of recent years 2018 is the 2nd highest, after 40cm in 2011, and just a bit above the 29cm in 2013 and 27cm in 2009.

The last 3 winters had all been at 0cm by this point in the winter, along with 2012 and 2010. But if we look at 1983-1995, that we really the peak of early melting in Edmonton. Out of those 13 winters there were only 2 that still had any measurable snow on the ground - 1987 at 1cm and 1989 at 10cm.

This chart shows how our snow built up over the winter. A big storm on Halloween bumped us up to about 10cm, and we stayed around there until some February storms pushed us up to around 30cm. And since then there hasn't been much melting, so things have stayed fairly constant as any snow that did melt was replaced with new snow.

In terms of when things might finally melt, if we look at some of the other years with lots of snow at this point of the winter, 2013 hit 0cm on April 26, 2011 hit it on April 28, and for 2009 it was April 16. If this year follows along then we still have a few weeks to go yet.

And there's also always the chance of new snow after we've hit 0cm. Last April was very snowy with 43cm of new snow, and that was enough to drag the melt out by a few more weeks.

Total Snowfall

So this year we have a lot of snow on the ground, but have we actually gotten more snow than normal? The answer is no. This chart shows the actual snowfall that we've received over the winter, and at the end of March we were sitting at 104.9cm, which is basically right on the average.

This chart also includes the snow for last winter, and it was about at the same point (even though the snowdepth had melted down to 0cm) before things took off again in April.

Snowy Months

Here's another view of how the snow fell during the winter, broken out by month. So far March has been the snowiest month at 28.2cm, with November in second place down at 19.4cm. September, October and March were all quite a bit above average, while December was very low.



This chart shows how many days of snow there were each month. Even though the 19cm of snow during November was pretty average, that was spread over 15 snowy days. March was in second place with 11 snowy days.

Large Snowfalls

And how do those snowy days break down? This chart shows how often we get a little bit of snow, or a lot of snow.

The long-term trends for Blatchford and the International are shown in Blue and Orange respectively. About half of the time when we get snow it's less than 1cm, and about 85% of the time it's less than 5cm.

The numbers for 2017-2018 are shown in green, and they're a pretty close match. We've had 52 days with snow so far this winter, and 28 of those were less than 1 cm, while 7 were 5-10cm.

This chart shows all of the big, multi-day snowfall events from this winter. Because snowstorms can often start in the afternoon and last until the next morning it makes sense to group consecutive days together, rather than separating the numbers by individual day.

So far this winter we've had 6 multi-day snowfalls of more than 5cm. The largest was 13.6cm over 5 days (which is maybe stretching the concept of consecutive days) at the end of February. But at the beginning of March we got 12.2cm over two days, and at Halloween it was 11.2cm over 2 days. The largest single-day snowfalls so far this winter were 9.4cm on March 3rd and 8.2cm on October 2nd.

If we just look at the April and May months here, we can see it's pretty common to get one or two 5cm+ snowstorms late in the year. Recently 2015-2016 didn't have one, and neither did 2004-2005, 2000-2001, 1998-1999 or 1997-1998. But all of the other years here had at least one, and so the chances of it happening again are pretty good.

Total Snowfall Each Winter

Our average snowfall each winter is about 125cm, and that's been fairly consistent going back to the 1880s. This chart is split between the data from Blatchford (1880-2007) and from the International Airport (1960-today).

Right now we're at 104.9cm of snow for the winter of 2017-2018, but we still have April & May left to go. On average in April & May we get about 20cm of snow, and so there's a good that this winter will probably end up right around the average.

And that's it for our look back at the snow so far for the winter of 2017-2018. It's always tough to know exactly which snow will be our final snow, but we'll check back in during the April review, and maybe the May review if it's needed.

Next week will be Part 3 of the 2017-2018 Winter in Review - The Winter City Showdown. We'll try to get a sense of how this winter compared in Edmonton, Calgary, Winnipeg & Montreal.