Prospects for Skiing

 Morning as broken revealing a fresh coat of snow on the Wasatch.  

The Alta-Collins snow depth currently sits at 8 inches.  I suspect there's a dramatic increase in snow depth from maybe an inch or two at 8500 feet to perhaps a foot or a bit more at 11000 feet.  It's a start.  

We have another cold trough moving in and bringing us another round of mountain snow later today through Wednesday morning.  This storm has been talked about for days, but we're now at a point where we can take a closer look.  The good news is it is a cold, juicy storm.  The bad news is that the upper-level closed low is passing to our south.  

As a result, the first part of the storm is dominated by easterly crest-level flow across the Wasatch Range as illustrated by the GFS 700-mb wind forecast valid 0900 UTC 12 Oct (3 AM MDT Tuesday morning) in the lower left-hand panel below. 

A look at the time-height section for Salt Lake City shows the moisture and cold air arriving a bit before 0000 UTC Tuesday (6 PM MDT Monday).  In other words, this afternoon.  In this first stage of the storm, the orographics are not great for the Cottonwoods.  Later in the event, from about 1800 UTC Tuesday through 1200 UTC Wednesday, the low-level flow becomes northwesterly, although there is a stable layer that could present a problem for good orographics during that period as well.  

My view is that this will be a snow producer, but one where we probably can't jack up precipitation and snowfall numbers for the Cottonwoods from those produced directly by the models. Below is what we are getting from our new GFS-derived Little Cottonwood forecast guidance product.  0.88" of water and about 9" of snow (at Alta-Collins) through Wednesday morning.  

For comparison, the Euro is a bit wetter (0.99") and the HRRR a bit drier (0.82").  

I'm inclined to go with these numbers for upper Little Cottonwood.  I'll go for 7 to 14" for Alta-Collins through Wednesday morning.  

A couple of wildcards. One is the easterly and southeasterly flow through Tuesday morning.  This could mean that the Wasatch Back and Brighton do better than Little Cottonwood through Tuesday morning.  It could mean a quick 4-8" at upper elevations near the Park City Ridgeline before the storm transitions to northwesterly flow Tuesday afternoon.  

The second is that there can be some precipitation banding in situations like this and it's not possible to pinpoint such bands at such lead times.  If one or more develop, they will affect local accumulations.  

There is also some hope for the next trough that will affect the area Wednesday night and Thursday.  We'll look at that in a future post.  

Bottom line: Cold and snow for the upper-elevations of Utah, although probably not a game changer (although it will help).  Nevertheless, ultramarathoning not recommended.