Wasatch to Get Some Too

Some HUGE storms have struck other regions of the Northern Hemisphere in recent days.  Previous posts describe 2+ meter dumps in the southern Limestone Alps of Europe (Another Alpine Dumpage Update) and Japan (Gosetsu Chitai Dumpage).  Adding insult to injury, huge snowfalls overnight in northern Pennsylvania and southern New York, including 44" at Newark Valley with snowfall rates of 4-5" per hour.

Snowfall reports received as of 8:30 am. An intense snow band set up overnight around the Binghamton NY area, producing snowfall rates of 4-5" per hour. Among the highest snowfall totals thus far: Newark Valley NY 44", Litchfield PA 43", and Binghamton NY and Vestal NY 41" pic.twitter.com/zopzr501Ao

— NWS Eastern Region (@NWSEastern) December 17, 2020

Lord have mercy!  

I can't promise snow totals of that magnitude for the storm that is developing today, but let's have a quick update on where things stand. 

We are currently in the prefrontal stage of the storm with the latest radar imagery showing the heaviest precipitation in the northern Wasatch as of 1625 UTC (0925 MST).  

As of 0900 MST, Alta-Collins has picked up .06" of water equivalent, but not enough snow on the board yet to tick off an inch.  The water numbers from the automated weather stations at Snowbasin show .02" or less by 0900 MST but the latest snow stake photo shows about an inch of snow.  Basically, things are just getting going.

In the Salt Lake Valley, we're presently in a "virga storm" situation with dry air at low levels.  The photo below, taken at 0820 MST shows snow virga falling aloft, but much of the snow sublimating before reaching the valley floor.  I did get hit by a few flakes while I was out on my walk.  

For the Salt Lake Valley and central Wasatch, we will remain pre-frontal today with southerly flow and periods of precipitation increasing in frequency and intensity as the day goes on.  Snow may mix with rain at times at the lowest elevations.  This morning, I saw a mixture of snow and "slush" as I was walking at 5000 feet elevation, but it changed over to snow when intensity increased.  The NWS is expecting impacts for the evening commute in Salt Lake County, so be alert.  The CDC recommends that you wear a mask when social distancing is not possible and the Utah Highway Patrol recommends that you slow down when the roads are wet, slushy, snowy, or icy.  

The HRRR is bringing the front through the northern Salt Lake Valley between 0200 and 0300 UTC (1900-2000 MST).  Should be an all elevations storm at this stage.  I like seeing the Salt Lake Valley and the central Wasatch covered in HRRR precipitation!  

We are having some networking problems and our usual products are not all available this morning.  Below is the NWS forecast summary is below.  2-4" for Salt Lake City, 3-5" for Ogden, 4-6" for Park City, and higher amounts in the mountains.  

Source: NWS

The Utah Avalanche Center is still advertising 8-14" for the central Wasatch, and that seems reasonable based on what I have.  Maybe we can do a bit better if things come together.  I'm inclined to think that less than 8" is unlikely for Alta from this one.  Tomorrow is a likely deep powder day, although the meager natural snowpack means low-tide conditions and as noted in the Utah Avalanche Center report, the backcountry avalanche hazard will likely be high.  The green light will not be on.  Let's be careful out there.