December, 2021.
Sarah and I rented the Lower Russian Lake USFS cabin on the Kenai Peninsula Christmas day. We planned to ski to the cabin, knowing that there was a lot of snow, but I checked satellite imagery to double check surface conditions. Yep, snow. But some dark zones on Skilak Lake caught my attention so we packed our skates as well.
After our night in the cabin, we drove to Skilak Lake, arriving in the late afternoon. The lake at the boat dock was a mix of snow with patches of rough ice. Not promising. But this wasn’t the dark zone we had seen on the imagery. We put on our skates and slowly worked our way west.
It didn’t take long to find the good ice—smooth and 3-4 inches thick (8-10 cm). A warm wind actively melted the snow on the lake, creating a veneer of water. I remember learning in high school physics that ice with a skim of water is the lowest friction surface that we encounter in the natural world. It felt like it!
We spent the remaining daylight in a mixed state of bliss and stress about ‘capturing the moment.’
Thinning ice
The ice was so good that we spent the night in Soldotna and returned to Skilak the next morning. After a few minutes on the ice, almost as an after thought, I stabbed the ice a few times with my probe and was shocked to punch through. I had tested this same zone the day before, and the ice was now one to two inches thinner!
Two inches of thinning in ~12 hours is very fast. I took a look at the weather history to figure out what happened.
Between 2 and 3 PM on the 26th, the temperature jumped from 29 to 40 ºF, and maximum wind speed from 0 to 15 mph. Clearly, a weather front quickly moved in. I don’t know much about weather fronts … if you do, please add some insight in the comments below!
The temperature stayed in the 40s until 1 AM, and above freezing until 9 AM. Meanwhile, the winds blew in the teens (max 23 mph) until midnight and then single digits until morning.
The wind is the key here … ice can actually thicken with above freezing air temperatures, especially in December when there isn’t much solar radiation. But wind! Wind works as a conveyor belt constantly stripping water vapor from the surface which promotes renewed evaporation. And with the warm air temperatures and melt water, Skilak was ripe for rapid evaporation.
The take-home lesson for me is to pay more attention to wind in the forecast. Wind plus warm air temperatures is a recipe for rapidly thinning ice! And a change from 3-4 inches to 1-2 inches is a big deal.
