Wednesday, December 7, 2016 at 6:33 am


Very cold air in place this morning with some dust on crust for the mountains.  Atmospheric River storm to affect the region starting late Thursday thru Saturday.  More storms likely for next week.


There is so much going on in Utah weather in the next 10 days, and the more you try to find answers, the more chaotic it becomes.  So, I’m going to keep things simple today and just stick to what we know.  I speculated quite a bit yesterday and despite loading the forecast with disclaimers, people still got more excited than I would have liked given my overall unease with the forecast.

First, we’ve got VERY cold air to deal with this morning.  Most locations are in the teens and single digits with some locations below zero.  I was hoping to get a read from Peter Sinks this morning (a notoriously cold basin in the northern Wasatch), but I don’t see any recent readings for this morning.  Yesterday morning at 5am, Peter Sinks dropped to -44F, and no, that is not a typo!  It could be even colder this morning…

As for snow with this “storm” yesterday and overnight?  It was pretty lame to be honest.  I was hoping for some lake enhancement and more widespread showers, but they never really got going.  Resorts reporting anywhere from zilch to 4″ at Park City.  No sleeper pow day 🙁   Just a bit of dust on crust….

The real action begins tomorrow (Thursday) as moisture increases through the day and precipitation should begin.  Initially, we could see snow levels down to valley floors as cold air remains in the region, but eventually snow levels should rise up to 6-7k feet for Friday.  Basically, we should see off and on pushes of valley rain and mountain snowfall thru Saturday as an atmospheric river takes aim.  Park City town and resort base could see a change over to rain late Friday into Friday night before snow levels drop again on Saturday.

This should be a great storm for base building, with quite a bit of dense snow to fill in all the cracks.  It won’t be blower powder, so perhaps the skiing won’t be great.  Also, avalanche danger will be very high, so check with UAC before heading into the backcountry this weekend.

I’m going to stick with the same forecast from yesterday 10-30″ of snow for the high mountains by late Saturday.  The reason for the large range is due to this storm’s higher snow levels.  Elevation will make a huge difference.  Lower parts of many resorts can expect somewhere closer to the low end of that range, while the higher, west-facing elevations can expect to be nearer the high end.  NWS has issued a winter storm watch for the area.

Updated look at QPF:

Univ of Utah

Univ of Utah

Generally 2-3″ of SWE for the Cottonwoods by Sunday.  Probably 1-2″ for other areas, which supports my forecasted amounts above.  Then you can see more action likely next week.

Best day to ski will probably be Saturday when it turns colder a bit, or Sunday, once resorts have had time to get some terrain open.

Long range:

Next week just looks so chaotic right now.  I’d love to give you details, but models don’t agree on timing or strength of anything.  Basically, it looks like we’ll have a second AR event for next week and we could see a prolonged period of wave after wave impacting the region.  These waves look a bit weaker than they did yesterday, but the prolonged nature means that mountains snow should continue to pile up with rain in the valleys.  Needless to say, it looks to remain active next week.


P.S.  No doubt I use some technical, weather-nerd jargon in my forecasts.  And I wish I had time to explain everything each time I wrote about it, but alas, I do not.  Many times I’ve been asked if there is a glossary to look things up.  I have linked the NOAA glossary on the Resources page, but it’s not fun reading. If you are looking for an enjoyable book to build a base (just like a snowpack) of how snow science and winter weather come together here in Utah (and elsewhere), then I highly recommend you pick up a copy of Secrets of the Greatest Snow on Earth by Jim Steenburgh.  Jim’s a professor of Atmospheric Sciences here at the University of Utah and he’s dedicated much of his life to answering the questions of what makes Utah’s snowfall so great.  I wouldn’t be half as accurate without some of the work he and his colleagues have done.

It’s an ideal Christmas gift for lovers of Utah snow and skiing.  Available online from Amazon and Barnes and Noble, and local booksellers Weller Book Works, Kings English, and Dolly’s Bookstore (call ahead for availability).


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9 thoughts on “Chaos

  1. RF

    Bought a ticket a month ago (when there was no snow yet) to come out Dec 10-13.. sometimes you luck out 🙂 NOAA seems to be forecasting totals of 16-32 for Alta through Saturday (just adding up their ranges), seems to be a bit more reasonable versus the apocalyptic totals seen with the GFS.. one question I had is about the short range ensemble. Do you normally see such disagreement between the ARW and NMB members (I’m not entirely sure what those stand for)?

    1. Peter Donner

      Jim Steenburgh has got a nice post where he explains his thinking behind adding the SREF to his site

      ARW Advanced Research version of the Weather Research and Forecasting Model (WRF-ARW)

      NMB Eulerian non-hydrostatic multi-scale model (NMMB)

      My casual observation is the NMB tends to group lower.

      SREF for Alta Collins mean matches the NAEFS, both have about 3 inches of water by Dec 11. I bugged Jim about adding a snow plume, he politely brushed me off.

      NAEFS mean snow is 40 inches by Dec 11, 65 inches by Dec 13. Min is 45 inches by the 13th.

      As Evan mentioned the rain/snow line looks like it could move into the mountains, maybe above Park City base.

      Evan titled this post well “Chaos”; it’s hard to believe this much water can come to the Wasatch in such a short period, but what is being predicted now happened in our beloved 2010/2011 season, Dec 17 to 23, 2010.

      As your financial adviser tells you, past performance does not guarantee future results.

  2. Florida Sam

    Hey WSF

    Based off you recommendations I bought Secrets of the Greatest Snow on Earth by Jim Steenburgh last year after ski Season and read it when it was 100 degrees in Florida.

    I have to totally agree with you, it’s an awesome read and great gift for Xmas! I really appreciate the recommendation, it was spot on.

    I’m not a meteorologist but I am an engineer so I do appreciate both the technical portions and ease or read of the book. Growing up in Florida, it filled me in on a lot of the terminology we just don’t have here.

    Keep up the awesome work!


  3. Trace Carrillo

    Please don’t eliminate the technical viewpoint or be afraid to use jargon! I know plenty of people with a basic weather knowledge that appreciate the opportunity to learn a bit more with each post. I know it must be hard to speak to such a broad audience, so nice job, and thank you!

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