2021/03/28

Zero Snowdepth for 2021

This is a little late, because after a warm start to March things have cooled off a bit, and that threw some uncertainty into the question of whether our snow has officially melted or not.


2020-2021 Snowdepth
In this chart the blue and orange lines are the snowdepth for the winter of 2020-2021 for Blatchford and the International respectively. The light blue stuff in the background shows the average and the range of snowdepths at the International over the past 30 years.

Blatchford's final recorded snowdepth this winter was on March 9th at 3cm, and after that snowdepth has been blank. The International hit 2cm on March 17th, and it hung out there until March 20th. On the 21st it had no meausurement, and since then it has been showing "Trace" amounts of snow on the ground. "Trace" doesn't mean 0cm, but it's close, and eventually it will disappear.

For the winter as a whole both stations jumped to well above average in early-November, and then were mostly flat through mid-February. Things started to drop in the last week of February, and then really fell off a cliff in the first week of March.


2020-2021 Snowdepth - Outlying Areas
For a bit more context, here the snowdepths for Stony Plain and Campsie (about 100km NW of Edmonton) are also shown.

Snowdepth seems to be Environment Canada's least precise measurement, but the Stony Plain and Campsie stations had less snowdepth for most of the winter than the two main Edmonton stations did. Stony Plain's snow disappeared about a week before Blatchford on March 2nd. For Campsie it was March 15th, which was a week after Blatchford and a week before the International.


Recent Winters
This chart has the history of snowdepths and melts for recent winters.

March 21st is pretty early for all of these stations to be snow-free, although 2015 and 2016 were both about a week earlier. But comparied to years like 2020, 2018 and 2013 this winter was about a month ahead.

People always like to joke about "second winter," and just because all of the snow has melted that doesn't mean that we won't get more. In April and May we average another 20cm of new snow, but looking at the snowdepths here that late-spring snow usually doesn't have much of an impact on the ground. 2015 and 2016 both had early melts, which were followed by another week of snow in late-March. And winters like 2017 and 2014 had fairly late melts, and after that the snow showed up again for another week in mid-late April.


Lasting Snow
In this chart each of the narrow blobs shows the length of time for which there was snow on the ground during each winter.

For the winter of 2020-2021 Blatchford had snow on the ground for 122 days in-a-row. That was from and early~ish start on November 8th through to the early finish on March 9th. In recent years 2019-2020 went 141 days and 2017-2018 went 170, while 2014-2015 went 95.

The International had measureable snow on the ground (we ignore the "trace" amounts in the chart) for 133 days, from November 8th through March 20th. 133 days is pretty low for the International: 2016-2017 went 134, 2015-2016 went 121, 2014-2015 went 126. For longer winters recently 2019-2020 was up at 169 days, with 2017-2018 at 172.

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