April Snowstorms

A few days ago we looked at April Rainfall, but with the recent weather it feels like April snowstorms are a more pressing concern.

Monthly Snowfall

I've said in the past that April is on-average about as snowy as February, but as of April 15th we're well past our April average. At 29cm April is now actually our snowiest month of the winter, beating out March at 27cm and October at 22cm.

April Snowstorms

This bubble chart shows all of the April snowfall events at the International Airport, going back to 1961. A snowfall "event" here is the total from several consecutive days of snow, and the bigger the bubble, the more the snow.

In the past 3 days we've received 24cm of snow, which makes it the largest snowstorm this winter - beating two 12cm storms in early-October and early-March. And earlier this April on the 3rd we got what seemed like a lot of snow, but it was actually only 4.2cm.

To make it easier to compare 2017 to previous years, lets bring in some numbers:

Here we're focusing on the big snowstorms. Since 1961, the International had 24 snowstorms in April with 10cm of snow or more, and 7 with 20cm or more.

The largest April snowstorm at the International was 40.7cm on April 6-7, 1991. And with 24cm from April 13-15th 2017, our recent snowstorm is actually the 4th snowiest April snowstorm ever recorded at the International.

In 2002 and 2004 we had similar, large snowfalls during this same week of April - 28.1cm and 19.2cm respectively. And both 2003 and 2008 had snowstorms around the 20cm mark even later in April. So this sort of thing is not uncommon, but it has been a few years since one of these happened - the most recent large~ish April snowfall was back in 2014 with 10.4cm.

Bubble charts can make it a little tough tough to get a sense of scale, so lets look at these snowfalls in a different format:

Here we have the daily snowfall as a 3d landscape, instead of the bubble chart.

I'd said previously that the largest April snowstorm was in 1991, and it appears here as the largest peak. The other ~20cm snowstorms are also all pretty visible, with our 24cm in 2017 off on the far right side.

In early April we can see plenty of little snowfalls, and in the middle of the month there seems to be a strange cluster of 15cm~20cm days. But then as we move into late April the number of snowfalls tapers off, although we still see some big days.

One final caveat, though:

This is the history of our snowfalls for May. And during May we get snow about half of the time. Sometimes it's a just a little bit, but sometimes it can be a lot.