Saturday, December 23, 2017

Water Equivalent Is More Important Than Snowfall Amount

Most ski reports and skiers tend to focus on snowfall amount as the measure of storm size, but for many applications, it is the water equivalent of the snowfall (i.e., how much water it contains) that is the most important measure.  After all, the water equivalent determines how much weight (and stress) you are adding to the snowpack, which is important for avalanches, and how much water you are adding to the snowpack for water resource purposes.  

Really, Utah skiers should also be focusing on water equivalent right now instead of snowfall amount.  We need base, and base is a function of how much water is in the snowpack.  Six inches of 15% water content snow goes a lot farther as six inches of 5% for building up base since it contains three times as much water mass.  

As I write this post at 7:15 AM, I'm encouraged by the current storm so far.  Storm-total water equivalents in the Wasatch so far include 0.9" at Ben Lomond Peak (through 6 am), 0.8" at Ben Lomond Trail (6 am), 0.74" at Snowbasin-Boardwalk (7 am), 0.6" at Lookout Peak (6 am), and 0.38" at Alta-Collins.  Those aren't big numbers, but they are welcome and they will help a great deal.  Plus, as can be inferred from the radar image below, snow showers look to continue.  

Source: NCAR/RAL
Indeed, the latest HRRR keeps us in the moisture plume for most of the morning, as evident in the forecast valid 1800 UTC (11 AM).  

Things should taper off in the afternoon, but let's hope we squeeze as much out of this as possible.  It will not get us near an average snowpack, but it's going to help with the ski conditions quite a bit at the resorts.  It should allow North Fork Park to get open for cross country skiing.  I think we're in some sort of ski purgatory right now for backcountry skiing, with a thin, weak snowpack in some areas and not really enough to ski elsewhere, but this gets us closer.  

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