When the Ice Leaves the Port

Lake Winnipesaukee is the largest lake in New Hampshire, US, at 185 km² (71.4 mi²) (8.4 mi)². I still find it interesting because for about 6 years I lived high above it and close in a cozy mother-in-law apartment, with a screened porch, and the Lake spread out before me like...well, like a big lake. At least a good part of it. 

Consequently, I can still spell "Winnipesaukee." 

From CoPilot:

The name "Winnipesaukee" is derived from the Algonquian language and translates to "The Smile of the Great Spirit" or "Beautiful Water in a High Place".

The Lake freezes over in the winter, and people go out ice-fishing, etc. There's an airport runway on the ice over in Alton on the east end of the Lake--"the only FAA-certified, plowed ice runway in the continental United States." It doesn't (viz. can't) open every year, but it did open this year. Global warming is affecting the Lake.

A popular metric in that region is the Lake's "ice-out" date.

Ice-Out is declared when the cruise ship MS Mount Washington can make it to every one of its ports: Center Harbor, Wolfeboro, Alton, Weirs Beach and Meredith. It is also considered the unofficial start to the boating season as well as the end of winter in New Hampshire.

These day a local pilot flies over the Lake multiple times a day this time of year to declare Ice-Out. I wrote about him for Yale Climate Connections several years ago.

There is also an "ice-in" date, but it's not as popular because it means the start of a long, cold, dark winter and nobody gets too hyped for that. (In truth winter there sets in long before ice-in, which usually is announced in January or early February.) But ice-out is a ritual of spring, and soon your cabin fever will break. About mid-May, if you can just hang on.

Anyway...and please pardon me if I've written about all this before somewhere on this blog...this year's Ice-out was declared this morning at 7:02 am. (Seems suspiciously exact, but anyway.) The time series of Ice-Out dates is carried by Wikipedia. I had to look up the time in the local news, and I only have times since 2020. For earlier years there is ice-out data, but no time, so I took it as noon.

Here's the time-series of ice-out dates on Winnipesaukee since 1887. The red line is the 30-year moving average.

So the 30-year moving average has decreased about 10 days since 1917, that is, ice-out arrives earlier. The linear trend is about -0.75 days/decade, but of course the R² is small, just 0.28. That's -7.5 days/century. A week per century. 

The data are a pretty decent proxy for global temperature. I should make a histogram. Soon. Maybe. 

BTW, there was a year without an ice-out date--2001, when I was living there--because there never was an ice-in--the Lake didn't freeze over that year. This was before smartphones so I don't have pictures of it. I did take a lousy picture with a digital camera, but can't find it now. Any more it's kind of like life started only when smartphones became ubiquitous.

Ice fisherman lost some trucks.

Addendum: Once up there I saw a section of the lake surface freeze over in real time--a rolling edge of freezing, maybe traveling over a half-mile. Maybe a mile. Took about 10-15 seconds. I wasn't sure if I really saw that or not--I thought I did, but it seemed impossible--so I contacted a few limnologists--scientists who study lakes--and more than one told me they'd heard of such a phenomenon, but had never seen it, and called me lucky or fortunate or some such word.

So, spring is coming even to New England. There's hope. Here in Oregon it's getting into the 70s. (Fahrenheit. About 20 degrees Celsius.)

Have a nice day.