Winter has returned to Jackson Hole today. This is good news for skiers and for rafters this summer. Jackson Lake is 77% full, and our snowpack is at 97% of normal for this date. (see http://www.wrds.uwyo.edu/wrds/nrcs/swegraph/swegraph.html for updates) A lot of people get confused by snowpack data and "snow water equivalents." For the uninitiated, here's how I understand it: There are many data collections sites placed all over the upper Snake River Drainages. Some are simple sticks in the ground, but many are "Snowtel" sites that are very sophisticated, sending data via satellite uplink. These stations not only measure the depth of the snow, but they also measure it's actual water content. Anybody who lives in snow country knows the difference between light snow and heavy snow. A few inches of heavy snow can contain more water than a foot of dry powder. So agencies are more interested in estimating the actual water content of the snowpack. When today's snow water equivalent is 97% for March 26, that means they take the amount of moisture in the snow today and compare it to the average for this same date over years past. 100% would be right at average, so we're very close to that. The magic date is about April 1. That's because April 1 is about the time that, on average, we have the deepest total snow on the ground in the mountains. On April 1, the vast majority of the winter snowpack has accumulated in the mountains, and from there forward, typically more snow melts than accumulates. I like to think that when we are at or near 100% on April 1, we've had an average year. And an "average" year of snow in Jackson Hole is a good thing, because on average, Jackson Hole is a pretty snowy place. So the word "average" makes it sound somehow, well, "average", but in truth it's a really good thing. Average snows mean plenty of water and good river flows and fewer forest fires. All good things!
