It's Still Snowing...

Wow, what a storm cycle.  

It continued to snow overnight in Little Cottonwood as well as much of northern Utah.  More on the latter in a minute, but let's first take a look at Alta.

The tabular output below includes hourly observations over the 24-hour period ending 0700 MST this morning.  The interval board was wiped after 0700 MST yesterday morning, when there was 15 inches on the board, and after 1600 MST yesterday afternoon, when there was 10 inches on the board.  It now sits at 20 inches.  Thus, the total for the 24-hour period from 0700 yesterday to 0700 today is a remarkable 30 inches.  

Looking at the entire storm cycle, total snow depth since 1100 MST 11 February has increased abou 30 inches (ignore the eroneous 136" measurements).  If you add up the interval board measurements at times of peak snow depth, you get a snowfall of 82".  

I guess it goes without saying that everything is coming unglued from a snowpack perspective.  The Town of Alta is in Maximum Security Interlodge this morning as avalanche mitigation efforts begin.  

TOA Max Security Interlodge Go to low levels away from windows, If you have a protocol for your building reply with head count when ready

— Alta Central (@AltaCentral) February 17, 2021

As a meteorologist, I love extreme weather, but these are times I get a deep pit in the stomach and I hope all turns out all right.  Our technology can help mitigate but not necessarily eliminate hazards and we need to remain cognizant of that fact.  

In the backcountry, the Utah Avalanche Center issued, for the first time that I can remember, an extreme avalanche danger for all aspects and elevations in the central Wasatch Range.  

This is essentially a red alert for all winter recreationists as avalanches in these situations can be long running and go into unusual areas.  

There's a lot of talk about this being a lake-effect storm. I want to take a little time here to say that is an oversimplification.  

The past 24 hours have featured remarkably moist, unstable, northwesterly flow.  Precipitation features have been developing across the region, not just downstream of the lake.  One example is the radar image below.  Areas circled in yellow are not downstream of the Great Salt Lake.  For example, you can see radar echoes over the Raft River Range northwest of the lake, over and upstream of the Wellsville Mountains, Cache Valley, and Bear River Range north and northeast of the lake, and over and upstream of the Stansbury Mountains southwest of the lake.  

If there was no Great Salt Lake, it would still be snowing.  

An argument can be made that the frequency and intensity of radar echoes over and downstream of the lake, in the area I've circled in red, is greater.  Thus, I think if you want to say this is a lake enhanced event, that's fine.  Calling it a lake-effect event is a convenient but overly simplified narrative convenience.  Yes, I know these are semantics that only scientists care about, but perhaps the people in Tremonton are wondering where all this lake effect came from. 

Regardless, this has been an incredible storm cycle and it's still snowing...