Wasatch Weather Weenies

In the wake of yesterday's epic storm, which produced a 2" at Alta-Collins, the biggest storm since Jan 7–8 and what qualifies for all intents and purposes as a deep-powder day , fog and low clouds have filled the lower elevations of the Great Salt Lake Basin and Cache Valley.  It was a cool scene this morning with fog behind downtown and in some cases fingering around the skyscrapers. GOES true-color satellite imagery for 1946 UTC (1246 MST) shows fog or low clouds covering the Great Salt Lake and surrounding playa, extending up through lowland areas and the Cache Valley to southeast Idaho.   Forecasting fog and low clouds sucks and I'm not good at it.  With the ridge building in, I wonder if it could linger for several days, possibly spreading in coverage, or if it might break up.  I also wonder if it could spread down into the Salt Lake Valley this afternoon as the lake breeze and up-valley flow advects it southward.  That's really a battle between the t...

Not much change on the weather front.  A weak system will come through tomorrow afternoon and evening.  Some models generate squat.  Others an inch or two.  A game changer it ain't. A look at last nights Utah snow ensemble shows that storm around 00z 29 Jan with a few of the members producing modest accumulation but the vast majority at 2" or less.  A few ensemble members call for something around 00Z 3 Feb, but most are producing paltry amounts.   It's only one model forecast, but the ECMWF HRES from this morning has a dreaded Rex block (high pressure "over" low pressure) along the west coast later next week.   Hope something slips through the net or that the model guidance is just out to lunch.  Even a few inches would be nice.

People keep asking me when it's going to snow.  My response? How the hell would I know? Things are grim.  It's OK to be cranky.   As a scientist, I like to look at the evidence.  I'm doing this at about 7:15 on a Wednesday night part way into a fine bottle of Chianti, which I find necessary to numb sting of the forecasts. Let's start with the GFS.  A paltry 0.04" of water and 0.7" of snow for Alta-Collins over the next week.  The Euro?  I don't have an equivalent graphic.  I've looked at the next 10 days.  it might have a few more scraps at times, but nothing to get excited about. The Utah Snow Ensemble?  Well, the Euro is in it along with 81 other forecasts from the European and US ensembles. It too is pretty grim.  The forecast below covers 10 days.  There's one member that produces just over 20 inches.  There's always hope.  There are 10 members total that produce more than 10 inches.  There's always hope...

The pollution layer over the Salt Lake Valley remains today (Saturday) but clearly shallowed over the past few days. The photo below was taken at 0743 MST Tuesday.  You can compare that with the one below taken at 0745 this morning. So, some temporary relief in some upper-bench areas.   On the valley floor, there was also some improvement, with PM2.5 this morning at Rose Park being lower than it has been in a few days. All of this is evidence of top-down mixing with the pollution being mixed out from the top down.  Sadly, it has not all been removed on the valley floor.  What remains after today we will probably be stuck with again for a while.

As discussed in the previous post , a weak upper-level trough was expected to move over northern Utah yesterday, but it was unclear if it would crack the inversion (I was skeptical).  Indeed, looking at things this morning, I'll call it "stirred not shaken." Impacts on the pollution are varied.  In the Avenues foothills, there was clear improvement and evidence that the pollution is shallower, as sometimes happens in a weak partial mixout event in which things are eroded from the top down.   On the other hand, a look at satellite imagery shows evidence of fog or low clouds in portions of the Salt Lake Valley, Tooele Valley, and the area from Bountiful to Layton.  Instead of being bright like the mountain snow, the fog and low clouds look grey, which may reflect that it is thin, patchy, or simply mixed with all of the smog that is still stuck on the valley floor.  Source: College of DuPage.  Image from 1611 UTC/0911 MST 16 Jan 2026. As I worked on this ...

Just another day in the paradise that is the Wasatch Front.  The latest west-facing image from the University of Utah shows a blanket of smog over downtown Salt Lake City.   Source: https://horel.chpc.utah.edu/camera_pages/wbbw.html It's tough to get above it without going to the mid elevations.  I hiked this morning to the top of the Avenues foothills and it was unclear if I was completely out of it even at 5700 feet.   Recent station (filled squares) and mobile (filled circles) PM2.5 observations show values in the valley generally between about 28 and 45 ug/m3.   Source: https://utahaq.chpc.utah.edu/ The threshold for unhealthy for sensitive groups is 35.5 ug/m3, so we are seeing values that are near or above that.  The DAQ sensor at Hawthorne Elementary is at 41.3 ug/m3 as of 2 PM.   Is there hope for a mix out?  The best chance is probably on Thursday and Friday.  On Thursday there is a weak upper-level trou...

January 8 marked the first day this season with an above median snowpack water equivalent at the Snowbird SNOTEL.  Hooray.  LCC is back, at least temporarily. The recovery from the storms over the past week in upper Little Cottonwood Canyon has been remarkable.  The skiing yesterday for a non-powder day was really great, with great groomers you could carve the hell out of and an open and well covered (or as covered as it ever gets) High-T providing access once again to "real skiing."   Although deep powder is the pinnacle of skiing, I always pinch myself on sunny groomer days like yesterday because I didn't know weather and snow like that were even possible when I was a kid in upstate New York.  Looking down Mambo and remember my roots Sadly the forecasts are dismal.  I don't know if I've ever seen the Utah Snow Ensemble completely flatlined for a 10-day period, but it is.   Actually there may be a couple of members in there that produce a sk...

The latest snow observations show very clear evidence of a "warm" snow drought, one in which the snowpack has been strongly affected by abnormally warm temperatures, resulting in a majority of precipitation falling as rain and periods of snowmelt or loss at low to mid elevations.   Evidence of this warm snow drought is especially clear if one looks at the yesterday's percentage of median 1991–2020 snowpack water equivalent at SNOTEL stations as a function of elevation.  As shown in the plot below, stations below 7600 feet are at 30-49% of median and, as indicated by the red bars, are all at all time minimums for their periods of records (which vary in length but extend back at least 27 years).   Source: NRCS In contrast, the percentage of median at higher elevation stations is higher and anywhere from 69–111%.  Yes, incredibly, both the Snowbird and Brighton SNOTELs are now sitting above median.  It's good to be at high altitude in the upper Cottonwood...

I'm supposedly on sabbatical this academic year, but the reality is that I've been working a ton with colleagues at the University of Utah and institutions planning, preparing, and now executing the SNOWSCAPE2026 field campaign. SNOWSCAPE is an acronym for the Seeded and Natural Orographic Winter Storms and CAtchment Processes Evaluation Project, with 2026 indicating that it is being held during the 2026 water year (we hope we may be able to do this in future years too).  This is the largest field campaign examining winter storms in northern Utah since the Intermountain Precipitation Experiment (IPEX) in 2000 and also includes a major snow hydrology component.   SNOWSCAPE is specifically examining winter-storm processes and the impacts of cloud seeding on snowfall, snowpack accumulation, snowmelt, and runoff in Utah's northern Wasatch Mountains and the lower Weber and Ogden basins.  We have established a one-of-a-kind transect of observing sites from the eastern end ...

Mother Nature brought the goods over the past two days.  Here are 48-hour water equivalents for the period ending at 11 AM 5 January: Ben Lomond Peak Snotel: 2.8" Snowbasin Boardwalk: 2.42" Brighton Snotel: 2.6" Alta-Collins: 3.73" Snowbird Snotel: 4.0" The trace of accumulated precipitation at Alta-Collins for the period snows that most of this fell in the past 24 hours.  In fact, the water-equivalent precipitation for the 24-hour period ending at 11 AM this morning was 3.03".  I'm always impressed by storms that produce 3" of water in 24 hours.   Source: MesoWest It's worth noting that this was a storm period characterized by southerly to southwesterly flow that shifted to westerly during the trough passage this morning.  Below is the wind speed (red line), gust (green plus signs), and wind direction (blue circles) on Mt. Baldy for the same period as above.  Note the predominance of southerly to southwesterly flow until around 0300 MST when ...

 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) ...

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 ...

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 th...