Light snow today, then a Frantic Friday storm

Wednesday, December 14, 2016 at 6:48 am

Summary:

Overrunning moisture will lead to light snow today for the high elevations, accumulations will be generally light.  A strong storm moves in for Friday with heavy high mountain snowfall likely with rain in the lower elevations.  Much colder temperatures for the weekend.

Details:

Today we have moisture streaming into the region ahead of an incoming storm.  This moisture is not particularly heavy or organized, by we should see plenty of clouds and light snow through much of the day for the high elevations.  Snow levels right now are near valley floors but those will rise throughout the day.  Perhaps topping above 7k feet by tonight.  I’d expect a just a few inches today for the high elevations.  The Cottonwoods and mountains north of SLC will be favored.  Should be enough to make for some soft turns at times today.

Tomorrow (Thursday) will be very warm ahead of the next system with temperatures on the mountain approaching 40F during the day Thursday.  Winds will be picking up and will be quite strong.

Storm pushes in on Thursday night with precipitation filling by morning on Friday.  A very strong cold front will push through during the day.  Ahead of the front, we’ll see rain all the way up to at least 8000 feet.  That means the bases of Park City and Snowbasin and others should see rain for the first half of this storm.  Even Cottonwoods bases could be subjected to some liquid precipitation.  The hope is that the cold air filters in quickly and that the intensity of the precipitation will lower snow levels more than guidance suggests.  The precipitation should be very intense during the day Friday.  The clash of this warm airmass and a very cold one behind the front, coupled with abundant moisture from another atmospheric river, will make for one hell of a storm.  Friday is going to be a frantic day of weather watching.

Snowfall maps for this storm…   12km NAM shows the following output for the Upper Cottonwoods:

You can see that after our slight snowfall today, the action picks up late Thursday night with the heaviest snow thru the day on Friday.  Snowfall totals greater than 20″.  Not bad at all!

The GFS map of total snowfall is even more robust:

Then, there’s a wildcard for orographic and lake effect snow behind the front Friday night.  That could add to totals in favored areas like the Cottonwoods.  Right now, our best tools for forecasting lake effect show a very high likelihood of some type of band forming, perhaps aimed at the Cottonwoods:

I highlighted the percent chance of lake effect at that given time and the most likely beneficiaries.  Looks like late Friday and early Saturday is our best chance.  I also highlighted the 700mb temperatures dropping to -20C.  That’s cold!   700mb is typically about 11,000 feet or so, roughly the elevation of Hidden Peak at Snowbird.  That means temps are dropping from 0C (32F) at 11k feet on Thursday night to -20C (-4F).   That’s a precipitous drop in temps!

For skiing purposes,  Friday is going to be frantic.  It will be wet with rain possible at the lower elevations, especially early in the day.  It will be windy (could be wind holds).  There’s even a threat for lightning (lightning holds?).  But, it could also be free refills, especially in the afternoon with the temperatures dropping.  Could get better by the minute…    Definitely a risk/reward kind of day.

Saturday is the much safer bet for a powder day for all without the risks of high winds, or lightning.  Should be fantastic!

Overall snowfall totals are very difficult because elevation will be such a factor with the high snow levels to begin this storm.  I think breaking it up into separate areas should be best.

  • Cottonwoods –  8-16″ for base elevations, 16-30″ for upper mountain.
  • Park City – 4-8″ for base elevations (after switch to snow),  8-16″ for upper mountain.
  • Snowbasin/PowMow/Beaver – 4-8″ for lower elevations of mountain, 10-24″ for upper mountain.
  • Brian Head – 8-14″

These totals are from Thursday evening thru Saturday morning.  Small changes in snow level details could dramatically change these, but it’s my best guess as of now.

Long range:

We have a bit of a break on Sunday.  Some clouds and maybe a chance for a light snow shower on Monday and Tuesday.  Next system that could bring accumulations looks to be about Wednesday of next week (Dec 21). Right now it doesn’t look major, but could offer a nice refresh.  More storms possible right before Christmas.

WSF





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  • Db

    I’m seeing a chance at a white Christmas. Nice!

  • HypnoQuail

    YAHOO!!

  • Brad

    Seems that this disorganized storm (today) is producing pretty well.