I’ve been thinking about how the time it takes to thaw the lake relates to when we start, and how this year fits the pattern. I pestered Sean C. for some data, and plotted it out as a Floating Bar Graph.
Oldest years are at the bottom, newest at the top. Each year gets a bar that starts on the inflection date (when the mean temperature rises above freezing for keeps) and ends on the date when the lake is ice-free.
You can see two kinds of information here:
First thing, there’s some hope that late thaws can go faster than early ones. Compare 2013 to 2012, for instance. It’s not always true, of course; a lot depends on the temperatures and the ice thickness.
Second thing, it looks like we’re having a crummy year. We’re certainly off to a late start.
I wasn’t sure how to show 2018, because the thaw’s still in progress, but here’s what I did. Inflection date was April 17. We know there’s still ice today, so that first week is dark blue. It would be extraordinary if the lake thawed in under 20 days, so that span is turquoise. I don’t think we’ll live up to the potential for a really fast thaw, because the ice is thick and the temperatures have been at or below normal. The white stretch with the blue outline is my best guess, which is why it ends with a question mark.
Sean sent me another graph of his own. It’s pretty cool, and it does more to look ahead.
This compares 2018 to best and worst recent years, in terms of how fast we reached enough accumulated warmth for a thaw after a winter like this one. That value is represented by the horizontal line at a Thawing Index of 200. That’s our target for this year.
2004 was slow to warm up. That’s the green line staggering along the lower path. I guess we’re lucky we didn’t have super thick ice that year.
2007 was much better. That’s the red line that shoots up steeply.
2018 is represented by the blue dots, and so far, we’ve been following a good path like 2007’s. We’ve risen from a mean temperature just above freezing to seasonal norms in just a few days. But the weather forecast says we won’t be able to keep up that kind of increase, and suggests we might follow a middle road like the yellow line. If we do, we end up ice-free around May 18.
I’ve been pessimistic about the below-normal temperatures in the long-term outlooks, but Sean’s graph suggests that even with the not-so-great forecast we have, we can still be fully thawed for the Victoria Day weekend.