Wednesday, April 28, 2021

The End of the Snow Accumulation Season

In all likelihood, yesterday marked the end of the snow accumulation season on upper-elevation northerly aspects in the northern Wasatch Range (we're past snow accumulation season at other elevations and aspects where the snowpack has been melting and running off for some time).  

Data from the Snowbird SNOTEL shows (9177 ft) shows that as of midnight last night we were at the highest snowpack water equivalent of the water year (which begins October 1) with 32.7 inches.  

Source: NRCS

That will almost certainly be the maximum for the year as the forecasts for the next few days suggest an abundance of sunny, warm weather through Saturday.  The snowpack at this location is ripe or near ripe, meaning it's warmed to near 0˚C and additional energy input into it will likely release meltwater.  A weak system on Sunday may bring a few flakes, but not enough to rebound from these losses.  

As a friend noted yesterday, this is pretty much right on the date of median peak snowpack water equivalent at this site (April 28th).  If you are wondering, the median peak is 42.9 inches, so peak this year is 76% of that.  Alternatively, you could ask what percentage of water years had a higher peak snowpack water equivalent than this one.  The answer to that is a bit over 70%.  

Bets on the last day of snow cover at this site? 

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