Wasatch Weather Weenies

I'm excited to share that the 2nd Edition of Secrets of the Greatest Snow on Earth is now available for pre-order! Preorder now at https://upcolorado.com/utah-state-university-press/item/6364-secrets-of-the-greatest-snow-on-earth-second-edition and use the code STEE23 and you'll get 40% off.   The book has been fully updated and has two new chapters.  There's now a deeper dive into microclimates beyond Utah, especially Japan and the Austrian Alps based on extensive and "very challenging" research in both regions.  Climate change is covered in greater depth with a look at recent snow and glacier trends in the western US and Alps and projections for changes in snow at western US ski areas.   The scheduled publication month is July.  If you're lucky, you'll have it to cool yourself off and raise the stoke for next season during the heat of summer.  

By now this is old news, but the big 900 has fallen at Alta.  Courtesy of the Alta Ski Patrol, below is the 6" measurement on Tuesday morning that put them over the top.   The previous seasonal snowfall record for the resort was 748 inches in 1981–82.  I wonder if they were collecting snowfall measurements then at the base or at the current Alta–Collins site and what the frequency of measurement was.  Perhaps someone from Alta Ski Patrol can comment.  Often such info is lost to the sands of time.   I'm curious to see where Alta-Guard ends up for the year.  Records there go back to 1945–46, although they are November to April rather than October to April.  The previous record is 745.4" for November to April set in 1994–95.  They haven't sent in their April observations to the Utah Avalanche Center yet.   A lot of people ask me about differences between the various measurement sites in upper Little Cottonwood.  There ar...

Alta is now closed for the season, but the race to 900 continues.   Snowfall since Oct 1 now sits at 894".  Tantalizingly close.  I hear rumors that Alta Ski Patrol sits at the ready to verify 900 when we get there.  These are, however, only rumors.   It appears we have one storm to get there before the end of the month, and that's from today through tomorrow as a closed low moves through northern Utah.  Below is the GFS forecast valid 0900 UTC 25 April (3 AM Tuesday) when the 500-mb low is forecast to be right over Salt Lake City.   With cold air aloft, this looks like a spring special.  Lots of convection with periods of mountain snow through tomorrow, possibly with thunder and lightning.  Storms will be hit or miss.  The GFS tries to get one last gasp of northwesterly flow going and the HRRR even generates a lake band Tuesday morning although it's centered over the Salt Lake Valley rather than the central Wasatch. Howev...

Closing weekend is upon us for many Utah ski resorts, including Alta.  It looks like Mother Nature will provide some frosting later today and tonight as a parting gift.   Below is the GFS forecast valid 0000 UTC 22 April (6 PM Friday) showing strong northwesterly flow with high integrated vapor transport impinging on the Wasatch Range.  Call it an atmospheric river if you want, although vapor transport values are only marginally near what is typically used as the atmospheric river threshold (250 kg/m/s).   Combined with a weak trough/front passage and of course great orographic forcing, we should see mountain snow showers develop during the day today and continue into the evening hours.  There may be a few snow showers into tomorrow, although right now the models are advertising minimal accumulations after tonight.   For Alta, the HRRR is putting out 0.57" of water and 4" of high density snow.  The high-density snow reflects the strong w...

I have a number of thoughts running through my head about our snowpack and snowfall that I'd like to share.  These do not really add up to a coherent story, so we'll call this scattered snowfall and snowpack snippets. Snowbird and Thaynes Canyon Not at All-Time Records Lots of records broken for snowpack water equivalent this season, but curiously the Snowbird and Thaynes Canyon (PCMR) SNOTEL stations are still not at all-time record snowpack water equivalents. Snowbird hit 73.8" and currently sits at a record for the date, but its all-time record maximum is 75.1", set on May 23 and May 31, 2011. Source: USDA Thaynes Canyon hit 40.1, but that isn't even a record for the date, and the maximum is 45.2" set on May 14, 2005. Source: USDA This is an interesting curiosity and it suggests to me that the snowpack in the highest elevations of the central Wasatch, while near the upper end of what has been observed previously, might not be that much of an outlier compa...

It may be hard to believe given the dry sunny weather over the weekend, yesterday's high at the Salt Lake City Airport of 74˚F, and today's forecast high of 72˚F, but another cold trough is on our doorstep.  The GFS forecasts the trough to be pushing into the Intermountain West at 1200 UTC 17 April (6 AM tomorrow morning.  In advance of it, we have a cold-frontal passage with a little valley rain and mountain snow developing overnight.   Then the deeper and colder part of the system moves in tomorrow.  Temperatures and snow levels will drop during the day and be near the valley floor by 0000 UTC 19 April (6 PM Tuesday), with 700-mb temperatures near -10˚C.  Thus, don't be surprised to see some flakes around late tomorrow in the valley, although  accumulations look to be limited right now.    In the mountains, let's begin with recognition of the fact that Alta Ski Area's seasonal snowfall now sits at 879".  That's 21 inches from the covet...

These are eventful times, and there is much to talk about today. First let's talk about the temperatures.  The monster swing over the past 10 days or so is well illustrated by the graphic below which is produced by the National Weather Service Forecast Office in Salt Lake City.  It shows the range of average temperatures (1991-2020) in green, record highs (top of red), and record lows (bottom of blues).  The range of observed temperatures each day are the dark blue bars.  On April 4th, the high temperature was only 33˚F.  By April 11th, it was 83˚F, a record high for the date.  Source: NWS Yesterday was a touch cooler, although we still hit 78˚F, marking three days in a row above 70˚F and five days in a row above 60˚F. As readers of this blog are well aware, this led to elevated avalanche hazard as we transitioned from dry to wet avalanches, a prolonged closure of Little Cottonwood Canyon, and regular afternoon closures of Big Cottonwood Canyon.  ...

Watching the goings on in Little Cottonwood Canyon makes me realize that when it comes to snow, there is such a thing as too much of a good thing in a season as well as in a storm. For Little Cottonwood, we have simply had too much snow this year and especially in the past few weeks.  Too many road closures, resort closures, etc. More importantly, too much risk for everyone working to keep the road open, the resorts open, services running, etc.   We would have been better off if we had gotten say 700 inches of snow at Alta instead of 877 inches, especially if the spigot was slowed over the past few weeks? Perhaps this year helps to delineate the upper boundary of the Goldilocks season in Little Cottonwood above which there is simply too much snow? Let the debate begin. Meanwhile, I've hung up the touring skis temporarily.  Yesterday I went skate skiing for the first time this season.  I've really missed it, although there are good reasons why I haven't been putt...

I'm still having a hard time wrapping my head around the events of this past winter and most recent storm cycle.  Little Cottonwood Canyon opened temporarily for downhill traffic this morning.  Like you, I've mainly received media snippets of the cataclysm along the highway, with many natural and human-triggered avalanches burying the road.  Coalpit #4, the lowest path in the canyon with historical evidence of reaching the highway, hit the road for the first time since 1983 per UDOT interviews.  Source: https://cottonwoodcanyons.udot.utah.gov/wp-content/uploads/2021/04/11107_2_LCC_Avalanche_Slide_Path_Zones_FIN.pdf Photos in the tweet below from Brian Schnee show aerial views of debris from several paths covering the road. 📸 Here’s an aerial view of Little Cottonwood Canyon showing some of the recent avalanche activity and the debris buildup along #SR210 . Photos from this morning show some massive slides in the White Pine area. pic.twitter.com/5KbX0lXhc9 — 𝐁𝐫𝐢𝐚...

We are deep into outlier mode with Mother Nature calling the shots in the Cottonwoods.  Storm-total snowfall reports from the NWS includes 67" at Snowbird and 63" at Alta.  Snow depth at Alta-Collins now at all-time levels, peaking at 248" last night and currently at 247".  I went to be last night hoping that the storm would end and I'd wake up to a couple of inches on the Collins stake.  Instead, it ended up being another 15.   The situation in the Cottonwoods is quite serious.  I can't remember Big Cottonwood closing for a full day, but that's what UDOT announced this morning.  It's possible it happened when Argenta hit the road in January 1996.  The Utah Avalanche Center report for that year said it was the first time in 50 years Argenta hit the road and West Porter ran huge, dusting cabins in Porter Fork (see Utah Avalanche Forecast Center Annual Report 1995–1996 , see pages 6–7). Alta Town Marshall Mike Morey issued the update below thi...

I am deeply conflicted right now.  I'm super excited to see the snow piling up.  It appeals to my meteorological and hedonistic senses. However, I'm once again deeply concerned about the avalanche situation.  We are just so far into outlier mode.  So much snow, greased paths, over 20 inches of water since March 1st, and now another enormous storm cycle.   Let's look at the numbers from Alta-Collins. 10 inches yesterday through 4 PM.  17 inches overnight through 5 AM.  6 inches in 2 hours from 5-7 AM.  That's 29 inches in 24 hours.  Water during that period 1.63", so that's about 5.6% water content on average.  Storm total water equivalent is now about 2.1".   One contributor to these snow totals was a lake-effect band that formed overnight.  We haven't seen such a well developed and long-lived band of this type in a long time.  Snowfall rates were also high mid canyon, which is consistent with the band position....

We are now a few hours into a long winter-storm period.  We picked up about 3-4" of heavy snow at my place overnight, but given the mild temps, the major roads were in good shape when I drove in early this morning.  Campus looks spectacular.   The wet snow is sticking to everything.  It makes for beautiful scenes, but might lead to downed limbs and powerlines as this stacks up.   In the mountains, overnight totals were greatest in the northern Wasatch.  Snowbasin is reporting 13" and PowMow 11".   Snowfall rates at Alta-Collins picked up after 4 AM.  I can't tell if the interval board was wiped at 4 AM or not from these observations.  If it was, they are up to 7" as of 7 AM.  Otherwise it's 5" with 0.45" of water.   As of 1329 UTC (0729 MDT) radar shows the frontal band parked right over the Salt Lake Valley, Utah Valley, and the central Wasatch, as the models have been advertising for a few days. I didn't try to...

Just last Tuesday I expressed Optimism for the Corn Harvest this season with the hope that we might see more white corn this spring.  No sooner said than on on Thursday I saw dust being reported in observations to the Utah Avalanche Center on Thursday .  I decided to have a look today while touring and lo' and behold there it was buried with the melt-freeze crust about 45 cm under the new snow from Thursday and Friday.   We just can't catch a break.  It's hard to say for sure where that dust came from.  I've looked over some of the PM2.5 data we have the the U and it's evolution relative to snowfall in the Wasatch and it's unclear.  It could have been during the strong southerly flow on Wednesday afternoon, but it's not a lock.  Sometimes the noise in the numbers makes conclusions difficult.  Perhaps others with eyeballs in the mountains have ideas.   On the plus side, that dust layer is now buried.  If we don't add another la...