Mid May Powder?

Spring powder has been limited this season with April and early May coming in relatively dry, warm, and at times windy and dusty.  

In April, Alta recorded 53.5" of snow, but 37.5" of that was on the first three days of April.  Automated obs suggest about 10" on the 6th of May and we gotten perhaps 4" yesterday.  

So if you are still looking for a late-season powder fix, Sunday has some potential.  The models are hinting at a digging trough and front to be moving through Sunday morning.  The GFS, for example, puts the front right over nothern Utah at 1500 UTC 18 May (9 AM MDT Sunday).  

Some of the models then call for unstable northwesterly flow thereafter, although the moisture, wind direction, and instability do vary some.  

For Alta-Collins, the GFS puts out 0.94" of water and 9" of snow from Saturday evening through Sunday evening, most of which falls with the frontal passage Sunday morning.  

The median forecast from the Utah Snow Ensemble for that period is a bit more optimistic with 0.99" of water and 11.5" of snow.  A look at the distribution shows that most members (about 75%) are more than .75" water and 9" of snow.  

If this timing holds, there could be a bit of a battle between getting the underlying snow surface buried as the snow stacks up and the potential for sun to trash the snow should it appear or simply do damage through the clouds once the front goes through if the snow doesn't keep coming.  The 4" or so of snow we got yesterday may help a bit with the former.  The latter is a crap shoot currently and wintertime aspects that are often friendly to powder even in warm weather are now getting a good deal of solar radiation because the mid-day sun is so high in the sky.   

You can't catch a fish without a line in the water.  It's probably worth baiting the hook and being ready to cast your line for this one depending on how the forecast plays out.   

Dusty Days

The past to days were quite dusty thanks to strong south winds in advance of a slow moving cold front that finally moved into the Salt Lake Valley last night.  Yesterday was the worst of it with dust filling the Salt Lake Valley in the afternoon, creating and apocalyptic scene.  

Scene looking south over the Salt Lake Valley from the upper Avenues at 6 PM

Observations from the University of Utah over the past two days show persistent southerly flow on Sunday with peak gusts reaching 40-45 miles per hour.  Those winds died down Sunday night before strengthening Monday morning.  The strongest winds of the period occurred Monday with gusts > 35 mph common from about 1100 to 2100 MDT and a peak gust of 48 mph.  

Source: MesoWest

A look at MesoWest data shows many valley locations in central and western Utah had peak gusts more than 50 mph.  A few examples include Parowan (61), Curlew Junction (60), Stockton (60), Simpson Springs (58), Baccus/SR111 (58), and I-215 at I-80 (58). 

The exposed lake bed of the Great Salt Lake gets a lot of attention for dust, but widespread, prolonged events like this tend to be pre-frontal with dust sources to the south, southwest, and west.  GOES satellite imagery from yesterday afternoon shows many dust sources over western Utah.  With yellow arrows I've highlighted four.  The first two are the playa area near Fish Springs in western Utah.  Another is in the Skull Valley.  A lot of dust was produced in these areas, but did not affect the Salt Lake Valley yesterday (although dust from these areas could have come in with the cold front last night).

Source: CIRA

The fourth in the southern part of the image and appears to be the Wah Wah Valley Hardpan south of the Sevier Dry Lake Bed.  It's unclear if dust from this area reached the Salt Lake Valley yesterday or extended into environs to the east.

The sources for the Salt Lake Valley, however, appeared to be many in the areas that I've circled in blue.  There appear to be many emission hotspots in this area, without any one obvious in this visible satellite loop.  Just to the west of it though I've identified one clear hot spot that produced a plume that one can clearly trace into the western Salt Lake Valley.

That plume emerges from an area that is near SR-36 between Vernon and Eureka and just to the west of Boulter Peak.  This is an area that was burned during the Boulter 2024 fire.  My best guess is that the burn scar is the source of this plume (h/t to University of Utah Research Assistant Professor Derek Malia for pointing this out).  

Source: https://app.watchduty.org/

Burn scars have been important sources of dust for the valley in the past.  The Milford Flat Fire (2007) was the largest wildfire in Utah history and its scar was a prolific dust producer for many years.  Fortunately, the land surface there appears to have recovered and is more resistant to dust emissions today.  

Could Snow Storage Work in Utah?

It's that time of year when I wish we could save some of the snow from this season for next season.  There's a dense snowpack at upper elevations and wouldn't it be great if we could save just some of it for next year.

Some resorts in Europe have been doing that, piling up snow and covering it with white, insulated blankets or sawdust to save it until next season.  Levi in Finland is perhaps best known for doing this (see https://www.wired.com/story/ski-resorts-are-stockpiling-snow-to-get-through-warm-winters/).  Now Sun Peaks Resort has become the first resort in Canada to do it.

Per the video above, they invested $170,000 (presumably CDN) for geotextile blankets to preserve snow for next season to use it in late fall and early winter.  

I don't know enough about resort economics, snowmaking costs, or snow energy balance to evaluate whether or not this would work here, but I'm intrigued.  Beyond costs, one advantage of this approach is that the preserved snow would be available even if snowmaking conditions were unreliable, such as might occur during a warm fall.  

At issue is how well this would work at a lower latitude.  I am aware of the use of geotextiles in the Alps to preserve glaciers, but am unaware of tests at at our latitude.  One could imagine using terrain maps to evaluate the total incoming solar radiation during the warm season, storing the snow in areas that minimize the total incoming solar radiation due to favorable aspects and shading by the surrounding topography.  

At Alta, could you stockpile snow at the base of Ballroom or below the shoulder traverse to cover Main Street next season?  

Last Day of 100 at Alta?

At 1 PM MDT this afternoon, the total snow depth at Alta Collins dropped to 99", falling below 100" for the first time this melt season.  There are a couple of cold troughs coming next week so a recovery is not impossible, but given that we're losing about 3" a day right now and have a couple warm days ahead, the odds are such that today was probably the last with a 100" snow depth this season.  

Cover in Collins Gulch remains excellent.  The snow earlier this week buried the snirty snow surface in some areas, especially on high north, making for a bit of a white corn harvest at upper elevations.  

Photo: Erik Steenburgh

Photo: Erik Steenburgh

Although there was a shallow freeze overnight thanks to the radiative cooling of the snow surface, given the warmth (the overnight low at Collins was 43) and the high elevation sun, it didn't take long for things to soften up anywhere that was in the sun.  We were off the mountain at 11 and eating tacos in the shade at Lone Star shortly thereafter.  In other words, a great May ski day. 

NSF Cuts Shutter NSF Unidata

There's an organization you may have never heard of, but if you are a user of weather data and graphics on the web, they have almost certainly contributed to the cyberinfrastructure that made it possible.

Their name is NSF Unidata, or just "Unidata" for short.  

Unidata developed organically in the 1980s when Universities has a pressing need to access weather data in real time, but couldn't.  The Internet at the time was nascent and there was essentially no hardware and software systems capable of delivering, processing, and analyzing weather data.  In 1983, a workshop at the University of Wisconsin involving about 80 US atmospheric sciences programs coined the name "unidata" and recommended that it be developed to provide:

1. Access to current and archived weather data, including satellite imagery and forecasts.
2. Support interactive computer capabilities at universities.
3. Communications capabilities between universities, the National Center for Atmospheric Research, and NASA.

These are things that we take for granted today, but would not have happened without Unidata.  Amongst the products they developed are the Local Data Manager (LDM) which acquires and shares data between providers and users like the National Weather Service, NASA, and universities; netCDF (Network Common Data Form) which is a file format for storing self-described, multidimensional scientific data; and metpy which is a collection of python tools for reading and processing weather data.  They have been transformative for the atmospheric and related sciences, with benefits not only for universities, but also the private and academic sectors and across the world.  

I have benefited and been actively involved with Unidata throughout my career, including volunteer service on their Users and Strategic Advisory (formerly Policy) Committees.  Last year I gave a short virtual talk on Unidata's history that provides some examples of the various ways that Unidata has benefited my career and the atmospheric and related sciences as a whole (apologies that the initial part of the talk is cutoff in the video below).

On 30 April, the National Science Foundation (NSF) froze funding for Unidata, with instructions to stop all funded actions until further notice.  Due to this freeze, most staff in the Unidata program center are being furloughed effective today.  The impacts on are fully summarized below.  

This is yet another example of the damage being done to the US scientific enterprise by the Trump Administration.  Unidata is an example of an organization that has widespread support from the University community because it develops and provides essential scientific services for research and education in the atmospheric and related sciences.  The radar feeds that you take for granted today on your smart phone were first developed by the Unidata CRAFT product.  The distribution of model forecasts that you can access today was first developed by the Unidata CONDUIT project.  And a lot of the graphics that you see on the web rely on Unidata MetPy and visualization software.

These disruptions of the scientific enterprise are pure insanity.  The halting of funding to Unidata will stymie scientific advancement, slow educational innovation, and limit classroom experiences.  

Blog Break

I'm going on a temporary hiatus for a couple of weeks.  Blogging may be light to non existent.  Congratulations to all of the University of Utah graduates, especially those from atmospheric sciences.