In the seventies, our snow-water records were Jay Penney’s hand-written notes that he brought along while we conducted snow surveys and Phil Farnes’ files in Bozeman. Now, the records are online, and we don’t even have to do the math. Still, this last cold snap and snowfall demonstrates why the percentage of normal isn’t a great measurement in early winter.
This two week plot shows Grave Creek nudging normal on February 21 with a couple of inches of precipitation showing up.
The next chart lets us see that we’ll need 3 inches more of precipitation to bring us up to normal by April 1 – and that’s not an unlikely thing.
As we go through March and April, temperatures begin to make a difference in precipitation and snowpack. Going back through 2012 to 2022, the April 1 temperatures at Stahl Peak vary considerably:
Date Year Temp
April 1 2012 28.9 F
April 1 2013 40.5 F
April 1 2014 26.1 F
April 1 2015 27.9 F
April 1 2016 40.5 F
April 1 2017 31.8 F
April 1 2018 22.5 F
April 1 2019 Not Recorded
April 1 2020 11.8 F
April 1 2021 36.9 F
April 1 2022 29.1 F
We could calculate standard deviation . . . and even go back to 1989 for temperature data on the site – but the most significant data is that snow melts when the temperature is over 32 degrees Fahrenheit. Three of the ten recorded years show melting snow, and seven do not. Here, we can see the maximum and minimum temperatures that have been recorded this year (for those who notice, the hydrologic year begins on October 1).
Trego's Mountain Ear 