A group of local weather watchers and forest managers made their annual trip up the Loop Road last week to gather snow core samples.
After the excursion, retired meteorologist Dave Lipson took the samples back to Riverton, where he tested them for moisture.
The information gleaned from the tests can help community managers plan for potential spring floods, Lipson said.
The group traveled up the Loop Road on May 5 – not long after a spring storm dropped several inches of snow in the area.
The conditions made it difficult to climb the Loop Road switchbacks in trucks, so Lipson said they switched to snow machines.
They pulled over at the highest point on the Loop Road, about 9,600 feet above sea level.
“If you’re coming from Lander it’s just a couple of curves away from Fiddler’s Lake,” Lipson said.
From there, they took a nearby two-track leading to the Blue Ridge Lookout, which Lipson described as “a big rock pile with steps kind of carved into the rock.”
“We pick Blue Ridge as a place to gather snow samples from, since water from there drains into both the Little and the Middle Popo Agie Rivers,” he explained.
Lipson estimated 18 inches of new snow had fallen on Blue Ridge that week, melting down to 15 inches by the time the group arrived in the area a few days later.
Once they left their snow machines behind, Lipson said they were “doing a lot of post-holing.”
Normally, it’s possible to walk on top of dense snowpack this time of year, Lipson noted.
The fact that they had to post-hole indicates that “the old snowpack beneath the new snow was dehydrated and somewhat hollowed out and crystallized.”
After taking in the view at Blue Ridge, the group found a sample site below the base of the lookout, in an area among the trees.
They began the core sample process by taking 10 snow depth measurements in the area using an avalanche probe, Lipson said.
“We’ll take an avalanche probe and stick it in the snow, then pull it out and mark where the top of the snow pack was on the avalanche probe,” he explained. “Then we take a tape measure and measure from the bottom of the avalanche probe … all the way up to where (it) was level with the top of the snowpack. That’s how we take a measurement.”
Once all 10 measurements were collected, the numbers were added together and divided by 10 to find the average snowpack depth for the area – in this case, 43 inches.
“The top 15 inches was what fell the day before, so there was an average of 28 inches of hard-packed snow beneath the new snow,” Lipson said. “Interestingly, about two feet down there was an extra tough layer to bust through, which could have indicated a thaw-freeze episode in the middle of the winter.”
Next, the group found a spot where the snowpack was actually 43 inches deep.
That’s where they took their core sample, using an official National Weather Service measuring cylinder.
“This canister has teeth on the open end of it to punch through hard-packed snow and ice usually found at the bottom of a snow core,” Lipson said. “This ensures that we get to the very bottom of the snow depth.”
The cylinder is only 36 inches long, so it had to be inserted and removed twice in this case to get a full sample of the 43-inch-deep snowpack, Lipson noted.
Once it was removed, the core sample was transferred to several tightly-sealed buckets and hauled back down the mountain for testing.
To test the snow core sample, Lipson said he waited until the material in the buckets melted, then poured the contents into a canister with a funnel on top attached to a long tube.
Next, he placed a measuring stick that is graduated to the tube into the container and recorded how high the water came up on the stick.
“We keep doing this, adding up all the numbers, until all the water is emptied from the buckets to get a total estimate of the number of inches of ‘snow-water equivalent’ there is in the snowpack,” he said.
Lipson said last week’s sample, at a snow depth of 43 inches, held a snow-water equivalent of 8.18 inches.
“This is rather low,” he said. “We speculated that (the) old snow was somewhat dehydrated and crystallized, as a lot of it must have fallen way back in the fall. It was a rather mild winter.”
Lipson shared the results of the snow core sample tests he has conducted over the past several years as well.
In 2021, the snow was 32.5 inches deep in the same area and had a snow-water equivalent of 10.79 inches.
In 2019, the snow was 33.41 inches deep, with a snow-water equivalent of 12.08 inches.
In 2018, the snow was 16 inches deep, with a snow-water equivalent of 6.96 inches.
In 2017, the snow was 68 inches deep, with a snow-water equivalent of 33 inches.