Extremely warm Lakes point to snowy months for millions
Wednesday, November 23, 2016, 9:45 PM - Great Lake temperatures are at a 16-year high for late November, and based on what's expected for the coming winter, southern Ontario is likely looking at some very snowy months ahead. Here's why.
Temperatures soared in the Great Lakes during summer 2016, reaching some of the highest values seen in the past 20 years.
Even now, as of November 21, lake temperatures are still well above average. They currently rank as the warmest since November 2000, and some parts of the lake are as much as 8oC warmer than they were in November 2014.
Lake temperatures, Nov 21, 2014. Credit: NOAA/Brian Bernard
Lake temperatures, Nov 21, 2016. Credit: NOAA/Brian Bernard
Difference in Lake temperatures, Nov 21, 2014 - Nov 21, 2016. Credit: NOAA/Brian Bernard
Why is November 2014 important? Because, based on our best reckoning, the overall weather patterns for the coming winter are expected to be similar to what they were like during the winter of 2014-2015.
What that means is, a combination of persistent warm lake waters and cold winds blowing across the lakes, which is a perfect setup for lake effect snow.
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The last time that the Great Lakes were anywhere close to being this warm in late November, in 2010, the lake surfaces remained mostly ice-free for the entire winter.
It wasn't until January 12, 2011 that Lake Erie - the shallowest of the Great Lakes and thus quickest to cool - was finally over 50 per cent frozen, but the overall lake coverage still hovered below 20 per cent. At the peak of the freeze, around the middle of February, Lake Erie had just over 90 per cent ice coverage, while the maximum for the entire lake system still only reached just over 40 per cent.
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That meant there was plenty of open water for lake effect squalls to tap into, and nature certainly took advantage of it. It didn't even wait until January to do so.
Exeter radar image from 12 noon EST, Dec 7, 2010. Credit: Environment Canada
The above radar image shows a snow squall streaming off of Lake Huron, which was part of a persistent snow squall event that lasted for a total of 109 hours, between Dec 4-7, 2010. London was hit with around 75 cm of snow, according to Environment Canada, while smaller communities saw well over 1 metre of snow by the time the skies finally cleared. The snowfall total for just this one event matched London's total snowfall for all of the previous winter, and it ranked as the costliest storm in the city's history.
Given how warm the lakes are this year, with water temperatures around 1-2oC higher than they were at this time in 2010, air temperatures of just a few degrees below freezing will be enough to set up prime conditions for snow squalls. At that point, it will just be up to the winds to set up just right, with just enough fetch over the water, to reproduce this kind of major snowfall event.
Exactly who gets hit by it, and how often, will simply come down to exactly which direction the winds are blowing at the time.
Teaser image courtesy: Brian Bernard