It's Snowing...

Winter took a while to arrive this year in northern Utah, but it is now delivering in spades.  

If I'm doing my math right, since 0600 UTC 12 February (2300 MST 11 February) the Alta-Collins interval snow stake has measured 54" of snow through 1400 UTC (0700 MST) this morning.  The Utah Avalanche Center site apparently has had enough this morning as when I went to pull it up, I got the dreaded "Too Many Connections" error.

Eventually I got through to find they have hoisted the rare black flag for extreme avalanche danger in the central Wasatch and western Uintas.  

Sadly that was the only page I was able to successfully load, so I will need to wait for more details.  

The radar image for 1457 UTC (0757 MST) this morning shows the long anticipated unstable northwesterly flow.  I didn't bother doing a loop this morning, but if I did it would show transient snow showers moving from northwest to southeast in the lowlands and more persistent stationary echoes over the mountains, consistent with orographic enhancement.  You can see some of this enhancement over the Stansbury, Oquirry, and Wasatch Ranges below.  

Little Cottonwood got raked overnight with 15 inches of snow since 1600 MST yesterday and overnight snowfall rates of up to 2 inches and hour.  The Alta-Collins snow depth is now up to...wait for it...107 inches!

Anyone want to pick the over-under for the opening of Little Cottonwood Canyon?  

Some sites that don't always do great in northwesterly flow were also blessed.  For example, the automated sensor at the Snowbasin-Boardwalk site is up to 16 inches since 1030 MST yesterday.  One reason for this is persistent banding that developed in that area yesterday evening, although they also did well overnight.  

Overnight snowfall on the Park City Ridgeline looks to be around 10 inches as automated sensors at Jupiter and Summit at Park City Mountain Resort look to have gotten to about 10-11 inches since 1600 MST yesterday.  I suspect snowfall is lower than that in town, but will let the locals comment. 

When will this end?  Given the scattered nature of these snow showers, there could be some breaks at times today or tonight, but snowshowers, at least in the Cottonwoods, look to continue into tomorrow.  The right hand violin plots for Alta-Collins suggest odds for the the heaviest snowfall are higher this morning and overnight, with a lull later this afternoon and tapering tomorrow.  

That's based on downscaling, however, rather than simulations of the processes that generate precipitation in these storms.  We will see how things play out.  

It looks like we'll get a break in the action on Thursday before the next storm on Friday.