An Upward Trend

 Despite recent posts grumbling about warmth and a lack of snow at low elevations, the reality is that the skiing at upper elevations has been incrementally improving and all elevations should see gains in snowpack over the next several days.  

The upward trend began on Christmas Eve, which was likely the worst day of skiing I've ever had in the Wasatch.  Simply an abomination.  I've been out 3 days since, all at Alta, and each day things have improved.  Groomers today were just fine and we should be happy about that given where we were several days ago.  

And the forecast for the coming work week looks pretty good.  Mean Utah Snow Ensemble SWE for Alta Collins through 12Z 10 January (5 AM MST Saturday) is a around 3" and snow close to 40".  The driest ensemble member is about 1.5" of water an 17" of snow.  

More importantly, temperatures are falling.  Tomorrow remains unseasonably mild, but temperatures (and snow levels) decline gradually Sunday night and Monday.  During the day Monday, snow levels look to fall to near bench levels and remain near or below that level through the work week.  

Let's hope Mother Nature bings further improvement to ski and snowpack conditions.

Pity the Low Elevations

There's some healthy precipitation numbers in the Wasatch from this storm including as of about 11 AM this morning (Jan 2nd):

Sundance: 4.29"
Tibble Fork: 2.48"
Collins: 1.82"
Mill D North: 1.40"
Farmington SNOTEL: 2.2"
Snowbasin Boardwalk: 2.84"
Ben Lomond Peak SNOTEL: 3.50"

That's the good news.  The bad news is that snow levels have been high (reaching as high as 9000 feet late yesterday in the central Wasatch) so this is yet another storm period in which the lower elevations got skunked.  The base of Park City, for example, remains free of natural snow.  

Source: https://www.parkcitymountain.com/the-mountain/mountain-conditions/mountain-cams.aspx

Thoughts and prayers to the Wasatch Back.

At mid elevations, where there is snow, its DENSE and water logged.  At the Ben Lomond Peak SNOTEL (7600 feet), there's currently 8.2" of water packed into a snowpack that is only 22" deep.  That's a water content of 37% or a density of 370 kg/m3, as one might find in a maritime snowpack.  

Meanwhile, in the Salt Lake Valley, we finally cracked the smog or fog at around noon today.  Yesterday afternoon there were some great views of the valley fog from the Avenues.

Paraphrasing Albus Dumbledore, "pity the low elevations and, above all, those elevations without snow."

Good Riddance to 2025

Happy New Years from the Wasatch Weather Weenies.

2025 is now in the rearview and I'm not sad to see it go.  It was a tough year for science, higher eduction, the climate system, and at least for the start of the 2025/26 ski season, snow.

Let's begin with the Murderer's Row of climate statistics for Salt Lake City.

First, 2025 was the warmest year on record (since 1875) with an averge temperature of 57.9°F.

The last 3 months of the year and the first 3 months of the 2026 water year (Oct-Dec) were also the warmest on record, with an average temperature of 48.9°F.

And of course December was the warmest on record with an average temperature of 43.7°F.

Shifting gears to the mountains and focusing on the past three month, water-year-to-date precipitation (water equivalent) is actually not all that bad.  Many stations are within 90 to 109% of median (green) and those that are lower than that are withing 90 to 89% of median.  

As shown for Snowbird, a big contributor was the early October rains.  Those were followed by a long dry stretch in late October and November.  December precipitation though hasn't been all that bad.  

The problem, however, is warmth. The early October precipitation was mostly rain.  Even at upper elevations, it didn't add up to much.  Then the precipitation we have had this month has occurred with exceptional warmth for December.  Natural snow cover below 8000 feet is currently scant due to a significant fraction of December precipitation falling as rain instead of snow.  Even above 10000 feet you can find a rain crust in the central Wasatch from the post-Christmas storm.  Snowmaking conditions have been limited.

And today snow levels will eventually get to about 8500 feet. 

So, the story of 2025 in northern Utah was warmth, warmth, warmth.  Good riddance. Let's hope 2026 is better.

Challenges Forecasting the Snow Level

The snow level is a critical variable for mountain weather forecasting, but it is both difficult to define and predict.  

In fact, there isn't even an agreed upon definition of snow level amongst meteorologists or the public.  One might say it is the level above which precipitation is snow and below which precipitation is rain, but its just not that simple.  Precipitation doesn't just change from snow to rain at a given altitude.  Snow takes time to melt as it falls.  Different types of snow crystals melt faster than others.  Sometimes it is snowing but not accumulating on the ground due to melt.  What do you do when there is a mixture of snow and rain or drizzle?  Where do you put the snow level? 

To begin, perhaps it is easier to begin with a description of the transition zone, the layer in which snow is warming, melting, and turning to rain as it falls.  

The schematic below provides a simple conceptual model of the transition zone.  The freezing level marks the top of the transition zone and is the highest level at which the temperature is 0°C.  Temperatures above this level are below 0°C.  

The transition zone (h/t Ron Stewart)

The freezing level and the snow level are not the same because snow does not melt instantly when it falls below the freezing level.  Instead, it begins a transition as it falls, gradually changing from dry snow to wet snow to slush (part ice part water) and finally rain.  The distance over which this occurs depends on many factors including the profiles of temperature and relative humidity below the freezing level, type and size of the snow crystals, and fall speed of the snow crystals. 

For example, if the relative humidity is low, a given snow crystal can penetrate farther below the freezing level since the crystal will warm more slowly because it is also cooled by sublimation.  A dense graupel particle can generally penetrate farther below the freezing level because they have a high fall speed and take longer to warm and melt fully compared to a small dendrite.  

In addition, because the melting of snow cools the atmosphere to the melting point (0C), there is often an isothermal 0C layer in the transition zone, as depicted above.  This layer can be quite deep, especially if precipitation rates are high.  Because of this effect, the snow level may lower some when the precipitation rate increases and rise some when the precipitation rate decreases. 

In the above schematic, I have denoted the level at which the precipitation is half snow and half slush as the snow level, but that may not conform to what you think is the snow level.  Perhaps it should be lower and at the level where precipitation is all rain or all rain or slush.  Alternatively, perhaps it should be higher and at the level where precipitation is all snow?  

Or, perhaps instead of focusing on the type of precipitation falling, we focus instead on the level at which snow is accumulating on the ground.  That's sometimes called the snow line.  But if we do that, what exactly is the ground?  Grassy surfaces?  Asphalt surfaces?  

There are many ambiguities.

As discussed in Van Cleave et al. 2011, about 15 years ago the National Weather Service Western Region actually established a definition of snow level for their applications:

"The snow level is the elevation above which snow will fall, and below which rain will fall. A mix of rain and snow may be observed at elevations within a few hundred feet of the snow level. Snow will not accumulate on the ground below the snow level and may not even accumulate at elevations above the snow level."

Even that definition is somewhat ambiguous, but they also defined techniques for calculating and forecasting the snow level and identified the wet bulb 0.5°C level as the best proxy for snow level in the western region. That said, there can be variations in precipitation type and accumulations on the ground around this level.  

One situation that can be particularly challenging involves stable layers in which wet-bulb temperatures are very near 0°C through a deep layer.  An example is provided by last night's GFS forecast for 1000 UTC 01 January 2026 (3 AM MST New Year's Day).  At that time, a precipitating cloud layer has spread over northern Utah in southwesterly flow aloft, but stable conditions remain at low levels as the cold air currently in place over the Salt Lake Valley is slow to mix out.  The freezing level in this case is located just above 750 mb, or near about 2500 m MSL (~8200 ft MSL).  Because the atmosphere is saturated at that level, the freezing level in this case also represents the wet-bulb zero level. However, below that level, the layer is very close to 0°C down to almost 800 mb.  This might enable snow to penetrate farther below the freezing level than if temperatures were increasing with decreasing altitude below the freezing level.  

Layers in which temperatures are relatively constant with height are called isothermal, which means having a constant temperature. Having a deep isothermal layer near 0°C is one way for the snow level to penetrate to low elevations.  One needs to keep a close eye on these layers as they can make a big difference for snow level forecasts.    

The Birth of "Snow Augmentation" at Sun Valley

While researching the 1976/77 drought year, I came across the article below in the Salt Lake Tribune describing the benefits of "Snow Augmentation" at Sun Valley (click to enlarge).  

Published in late December 1976 when Utah resorts were not operating due to a lack of snow, it describes initial use of artificial snowmaking at Sun Valley.  Today, Sun Valley probably has one of the best snowmaking systems in the world.  At that time, during the great snow drought of 1976/77, it enabled three runs to be open for the holidays.  As described in the article,

"Ribbons of artificial snow from two to three feet deep have been shot by air compressor-activated snow guns up to two-thirds of the way up the mountain."  

It goes on describe the artificial snow as "cube like crystals" with "a bit more density than nature's snow."  I'm sure that sounds familiar to today's skiers.  The system sounded pretty cutting edge for the time, pulling 1400 gallons a minute and putting down two acre-feet of snow in eight hours.  

I suspect in 1976 there were no Utah ski resorts with snowmaking.  It would be interesting to look into the history of snowmaking investment and expansion at our resorts.  Online articles suggest Deer Valley had a snowmaking system when it opened in 1981.  Prior to the 2002 Olympics, Snowbasin expanded and installed what was probably at the time the state's most expansive and sophisticated snowmaking system.  My recollection is that Alta was not yet making snow when I moved here in 1995, but perhaps my memory is inaccurate.  AI tells a lot of good stories, but they can be authoritative BS so I'm reluctant to use it here.  

That said, as we have learned this season, most contemporary snowmaking systems today are still at the mercy of Mother Nature.   If wet-bulb temperatures are too high, snowmaking efforts are hopeless.  This has been a major issue in Utah so far this season (although guns will be roaring in the during and in the wake of this latest cold surge).  All-weather snowmaking systems are available, but are expensive to buy and operate and not used to cover large areas of terrain.  

Let's hope we see a colder, snowier pattern emerge for 2026.  

Is This The Worst Christmas Skiing Ever in Utah?

I never like to bad mouth Utah skiing but I think it is accurate to say that this is a truly abysmal start to the ski season right up there with many of the worst seasonal starts on record.  

But is it the worst?  

Currently on this Christmas Day there is little to no natural snow at low-to-mid elevations.  For example, the base of Park City is as bad as it gets right now from a natural snow perspective, although there is a white ribbon of death thanks to artificial snowmaking.   

Source: https://www.parkcitymountain.com/the-mountain/mountain-conditions/mountain-cams.aspx. Screenshot from 1:20 PM MST 25 Dec 2025.

Where we have data, there are now several SNOTELs in the Wasatch Range that are at their record low snowpack water equivalent for the date.  These SNOTELs are Ben Lomond Trail, Farmington Lower, Farmington, Hardscrabble, Parley's Summit, and Payson Ranger Station.  At Ben Lomond Peak (records back to the 1978/79 winter), the 4.5" of SWE is just ahead of the record low of 3.7".  At Snowbird (records back to the 1989/90 water year) the 6.0" of SWE is just ahead of the record low of 4.6".

So, at some sites we have the worst natural snowpack during the SNOTEL period of record for Christmas.  Others are close. 

But "during the SNOTEL period of record" is an important caveat.  The oldest SNOTEL stations in the Wasatch Range began operations during the 1978/79 winter.  Others have even shorter records.  They fail to provide a comparison with what is the worst Christmas and ski season start on record:

1976/77

How bad was the start of the 1976/77 ski season?  During November and December of 1976, Alta-Guard observed only 31" of snow and 2.04" of water equivalent precipitation.  How low is that?  Really low.  For comparison, Alta ski area has recorded 44.5" of snow and 6.75" of water so far this November and December (they will get more through this weekend) and the Atwater SNOTEL which is located where those Alta Guard snow and precipitation measurements would have been taken in 1976 has 6.9" of water equivalent in the snowpack.  Thus, precipitation in 1976/77 and far less than we have had this November and December.  

There was also no snowmaking in 1976/77.  Snowmaking has been limited this year due to warmth (more on this below), but it still has saved our bacon and allowed resorts to operate with limited terrain.  In 1976/77 the ski areas didn't have it and weren't even open for skiing during the Christmas Holidays.  Back in 1976 there were these things called "newspapers."  They printed the latest news on paper and were delivered to your door.  It was a predecessor to modern social media.  On December 24, 1976, the Salt Lake Tribune contained an article entitled "Resorts Featuring Snowless Events."  Park City was promoting golf and tennis, gondola rides to view the new Jupiter Bowl Ski Runs, and dryland training classes.  Snowbird had "summer rates," tram rides, and music.  Perhaps it was a predecessor to Octoberfest.

What made 1976 so bad?  The short answer is a big ridge.  Average 500-mb heights for November 1 to December 23, 1976 show a high amplitude ridge along the Pacific coast that acted to reduce storminess, yielding few storms.   Basically, it was a very dry pattern.  

In contrast, the mean pattern for the same period this year is far less amplified and although we are below average for precipitation in November and December, we have had some storms.  

The complicating factor this year, however, has been the warmth.  The high fraction of precipitation falling as rain instead of snow and frequent snow-loss events have prevented the buildup of a low-to-mid elevation snowpack.  

How warm has it been?  To use a scientific term, it has been bat-sh*t-crazy warm.  Below is a time series of mean Nov 1 to Dec 24 temperatures in Salt Lake City since 1875.  Do you see that data point on the far right?  The one that sticks up way above everything else?  That's this year.  

The mean temperature for 1 Nov to 24 Dec at the airport was 47F.  This is 4.1F warmer than the next warmest (42.9F in 1995).  That's like running a 3 minute mile.  Simply unbelievable.  

Unfortunately, we don't have complete records for temperatures at mountain sites.  There's data at Alta back to the 1940s, but there are a lot of missing days.  For what it's worth, the average temperature at Alta for the same November 1 to December 24 period was 35F this year (with complete data coverage).  That's the highest on record, but in other years, there's missing data, so this comparison is limited.  For what it's worth, the average temperature for the same period in 1976, when records were also complete, was 30.1F.

So to summarize, the worst Christmas skiing was in 1976/77.  There was practically no natural snow, even at upper elevations, due to persistent ridging and a lack of storms.  Precipitation was far less than we have seen so far this season and there was no snowmaking infrastructure to save the day.  

But this season is also different animal.  We have seen unusually high temperatures that are really unprecedented and exceptional in the Salt Lake Valley.  More analysis of the mountain observations is needed, but even at upper elevations this appears to have been a remarkably warm period.  This has led to a high fraction of precipitation falling as rain instead of snow at low-to-mid elevations and frequent snow ablation events.  We have even seen a substantial rain event at elevations up to about 9600 feet.  As a result, there's either no or very little snowpack below 8000 feet and a thin snowpack at higher elevations.  Although we now have snowmaking infrastructure, it has frequently sat dormant due to high temperatures.   

Skiing during the 1976/77 holiday period was bad due to a dry snow drought, but it's bad this season due to a dry-warm compound snow drought.  In a dry-warm compound snow drought, warmth exacerbates the impacts of below average precipitation, making a bad situation worse.  I suspect there is no historical analog to the start of this season in northern Utah.  We simply haven't ever seen temperatures in November and December this warm (and this sustained).  A good research question concerns whether or not this reflects an ongoing transition into a future in which dry-warm compound snow droughts become more common, especially during the early season.  This season is not a new normal, but it might reflect a new extreme that became more likely due to warming of the climate system.  

That said, it will be cold this weekend.  You may need to recalibrate.