El Niño Update

The Climate Prediction Center (CPC) issued their June El Niño/Southern Oscillation (ENSO) discussion today (June 11) and it's almost certain to send some people into a tizzy, although those of us in Utah should be cautious about what to expect this coming winter.  

Before diving in, let's first talk about what ENSO and El Niño are.  ENSO is a natural cycle in atmospheric and oceanic conditions in the tropical Pacific characterized by a two to seven year cycle between warm phases (El Niño) in which the easterly trade winds weaken and the central and/or eastern tropical Pacific becomes anomalously warm and cold phases (La Niña) in which the easterly trade winds strengthen and the central and/or eastern tropical Pacific becomes anomalously cold.  

Various indices exist to illustrate the phase (and strength) of ENSO.  None of these is perfect since you are boiling down a complex ocean and atmosphere system to a single number.  I tend to favor the multivariate ENSO index or MEI.  Going back to 1979, the MEI has fluctuated between about -2.5 and 3.  Values greater than one indicate moderate to strong El Niño conditions.  Values less than one indicate moderate to strong La Niña conditions.  Two of the strongest El Niño events since the start of the 20th century are evident below: 1982-83 and 1997-98.  The 1925-26 El Niño is also in there amongst the strongest El Niños since 1900.  

Source: https://psl.noaa.gov/enso/mei/

As summarized in the CPC discussion, El Niño conditions, characterized by above-average sea-surface temperatures (SSTs) in the central and eastern equatorial Pacific, over the past month.  The figure below shows the departure of sea-surface temperatures from average for the week centered on 3 June and illustrates the anamalously warm SST not only in the central and equatorial Pacific, but also along the South American coast (as is often the case during El Niño).   

Source: CPC

There has been a lot of talk in the media about this being a "super" El Niño.  CPC doesn't use such flamboyant language, and in their May update they were very careful not to heavily weight the possibility of a strong El Niño, but in this June update they say the odds are stacked for a strong one:

"There is a 63% chance of a very strong El Niño during November-January [Fig. 8] that would rank among the largest El Niño events in the historical record going back to 1950."

So a very strong El Niño is not a lock, but is more likely than not.  At this lead time, that's probably the strongest confidence you are likely to see from CPC about a very strong event.  

However, and this is important for Utah skiers to consider, they also add the caveat:

"Even very strong El Niño events do not lead to the expected impact everywhere, but stronger events can more significantly tilt the odds in favor of expected outcomes."

And what are those expected outcomes?   For December-February Precipitation, CPC indicates greater than average odds for above normal precipitation across mos of the southern US including the southwest and below normal precipitation in the northwest interior.  As is often the case, there's no strong weighting for northern Utah.  

Source: CPC

One of the reasons for this is that there has been a lot of variability in precipitation in December to February during strong El Niño events. Below are postage stamps of precipitation during strong El Niño events so look for yourself.  

Source: CPC

I expect a lot of talk about what happened during 1982/83 and 1997/98 since those are the two strongest El Niño events.  Both of those events produced above average and very significant precipitation in California, the Wasatch, and Arizona.  At issue is whether or not those two "very strong" events are a reasonable sample or if the range of strong El Niño events that includes those and other events that were not quite as strong is a more reasonable representation of the range of possibilities.  As winter approaches, perhaps numerical seasonal forecasts will also have something to say, but I'm inclined to say that what will happen with precipitation this coming December to February is still up in the air.  There's no loading of the dice yet.  

That said, there is some loading of the dice that December to February will be warmer than average.  

Source CPC

That doesn't necessarily mean a repeat of last season.  A lot will depend on storm characteristics that we cannot anticipate this far in advance.  

Keep calm and carry on.  

The End Is Nigh

 The seasonal snowpack at Alta is nearly gone as indicated by yesterday's Mt. Baldy web cam

Source: https://www.alta.com/weather

and observations from Alta-Collins which indicate a total snow depth of 8 inches. 

Automated snow depth observations are such that the instrument might still suggest a few inches of snow on the ground when there is none.  That said, the end is nigh even with the overnight frontal passage, which might only delay the inevitable a day or two. 

Meanwhile, in the Alps, it is snowing at upper elevations!

Source: https://www.foto-webcam.eu/webcam/zugspitze/

Climate Change and Nordic Skiing

The vast majority (nearly all) studies examining the impacts of climate change on skiing focus on Alpine skiing resorts.  However, the reality is that Nordic (i.e., cross-country) skiing is far more vulnerable to climate change as anyone who has a long tooth and skis at Mountain Dell or Round Valley has observed.  

The primary reason for this is elevation.  As an example, below is a photo that I took from the summit of the Rangger Köpfl, a 2000-meter peak from which one can see the Wetterstein Alps and Karwendel Alps of Germany and Austria.  South of the Wetterstein Alps and west (left) of the Karwendel Alps sits the Seefelder Plateau, a famous cross country region that hosted the 2019 Nordic World Championships and has about 245 km of trails connecting the villages of Seefeld, Leutasch, Mösern, Reith and Scharnitz.  

With elevations around 1200 meters, the Seefelder Plateau is promoted as a snow-reliable cross country skiing region.  However, this is still an elevation that is quite vulnerable to climate change and lower than the adjoining Rosshütte Alpine ski resort (also pictured) which extends from 1230 to 2064 meters. 

Consistent with the Seefelder Plateau region, Nordic resorts often lie at relatively low elevations, whereas nearby Alpine resorts reach to higher elevations.  To illustrate this, the figure below shows the mean elevation of Alpine (downhill) and Nordic (cross-country) ski areas in the Alps (AT=Austria; DE=Germany; IT=Italy; CH=Switzerland; FR=France; SL = Slovenia.  There is a clear bias to lower elevations for Nordic ski areas that is especially pronounced in the eastern Alps (Austria and Germany).  The bias is not as large in the western and southern Alps where Nordic ski areas have higher elevations, although unlike Alpine ski resorts, there are no Nordic resorts with mean elevations above 2400 meters.  

Source: Schilling et al. (2026)

Nordic resorts are so vulnerable to climate change because negative trends in snowfall and snow cover are largest at lower elevations.  In other words, the snowpack will suffer more at lower elevations than at upper elevations.  

This is happening already.  Schilling et al. (2026) recently used satellite data to examine long-term (1980–2024) and short-term (1999–2024) trends in the percentage of Nordic resort trail kilometers that lie above the snow-line elevation.  Below are the results for the late season (March and April) and full season (November to April).  Circles indicate the long term trend, diamonds the short-term trend, and orange fill indicates that the trends are statistically significant at a 95% confidence level.  Elevation along the x-axis is based on the resort mean elevation.  Long- and short-term trends in the percentage of Nordic resort trail kilometers during the late season are either flat or negative at nearly every resort.  Seasonal trends are also flat or negative at all but a few resorts.  Declines vary by resort, but the largest are generally at lower elevations.

Source: Schilling et al. (2026)

Geographically, large regions with negative trends  in the southwestern Alps of France and Italy and the southeastern Alps of Italy (e.g., Dolomites, etc.).  

Source: Schilling et al. (2026)

For the full season, the average trend was a decline of 1.1% per year in the percentage of Nordic resort trail kilometers above the snow line.  

There are some limitations to this study given it's use of satellite data back to 1979 when overpasses were somewhat infrequent, but in general these results are consistent with what is seen in directly measured snow cover trends from the Alps, with declines in seasonal snow cover duration largest at lower elevations.  

Much like Alpine skiing, Nordic resorts at higher elevations will have a competitive advantage for in the future due to smaller declines in natural snowpack.  This would include places like Alpe di Suisi/Seiser Alm in the Dolomites (around 1800 meters) or the Engadin Valley in Switzerland (also near 1800 meters).  That said, the demands of cross country skiing are such that high elevation is not something that many Nordic skiers might want to do, especially those who live nearer to sea level. 

Snowmaking and farming are becoming more common at some Nordic ski resorts.  On the Seefelder plateau, about 20 km of trail can be covered with artificial snow in Seefeld and another 6 km in Leutasch.  More expansion of such efforts is probably essential in the future at many resorts.  In Utah, Soldier Hollow is now experimenting with snow storage under geotextile fabrics to save snow through the summer for the next season.  

There is still time to save Nordic skiing, but it will require reducing carbon emissions and limiting future global warming.  

Temporary Halt of the Dismantling of NCAR

The National Center for Atmospheric Research Mesa Lab.  Source: Aaron Seltzer/Getty Images.

Earlier this year, the Trump administration moved to dismantle the National Center for Atmospheric Research (NCAR). One component of that dismantling was temporarily halted earlier this week by a Federal judge in Colorado.    

NCAR is run by the University Corporation for Atmospheric Research (UCAR), which was founded in 1959 and is a non-profit consortium involving more than 100 institutions of higher education.  In February, the National Science Foundation (under the direction of the Trump Administration) informed UCAR that it would transfer management and operations of the NCAR-Wyoming Supercomputer Center (NWSC) to a third-party operator.  UCAR's lawsuit argued this was a violation of federal law.  The temporary halt was imposed by after the Federal judge in Colorado decided that the transfer was arbitrary and capricious. More information is available at https://eos.org/research-and-developments/judge-blocks-nsf-from-dismantling. 

This is, however, a temporary reprieve and efforts to dismantle NCAR by the Trump administration will continue.  Real damage is being done to atmospheric science (and American science in general) by these and other actions by the Trump administration. 

NCAR is undoubtably the leading center for atmospheric research in the world.  Other major centers, like the European Center for Medium Range Weather Forecasting (ECMWF), Met Office Hadley Center, or Max Plank Institute for Meteorology have more focused missions and lack the breadth of NCAR.  NCAR also has strong ties to universities and provides important collaboration, education, and training opportunities for University faculty and students.  

NCAR has been an important thread through my entire career.  As a graduate student, I began to work with an atmospheric modeling system that was jointly developed by NCAR and Penn State University.  This modeling system, known as MM4, eventually became the MM5, which was ultimately replaced by what we know today as the Weather Research and Forecasting model (WRF).  In the early 1990s, there were only a handful of MM4 users, but by 2021 there were almost 60,000 registered users of WRF.  It is used for operational forecasting (e.g., the HRRR is based on WRF), simulations of historical events to enable diagnostic calculations or sensitivity studies not possible with observations alone, and regional climate simulations.  Many private sector companies use WRF.  

I have also been involved in field campaigns that have used NCAR's observing systems and field program support services.  The observing systems include heavily heavily instrumented Gulfstream G-V and C-130 aircraft, a polarimetric radar facility, and a variety of surface-based atmospheric sounding and profiling systems.  NCAR is vitally important for field campaign management, which can be highly complex involving in some cases hundreds of scientists and students spanning institutions not just in the United States but often in many countries (and field campaigns are often international in nature and NCAR serves a critical role here as well).  

I don't know how we got to a place where we are talking about dismantling a critical facility for the future of the Nation and humanity, but here we are.  Given the impacts of weather-related disasters in the US, we should be investing in NCAR rather than tearing it down.  Building weather and climate resiliency requires advanced knowledge and cutting-edge modeling tools.  NCAR is a wise investment for a country that experiences the greatest diversity of high-impact weather in the world and a planet that is in the early stages of abrupt and rapid climate change.  

Give Me a Reason to Come Home

I haven't enjoyed hiking like this in many years.  So many mountains in the eastern Alps and so little time.  Austria is truly an amazing place.  

With our time here winding down we're on the 2-3 hike per week schedule, including excursions near Innsbruck or right from our apartment when time is tight.  

Last Friday I did a hike up the Niederer Burgstall, a 2400 m peak in the Stubai Alps just a 35 minute bus ride from Innsbruck.  The terrain here reaches to near 3200 meters and the views are spectacular.   

A view from my descent of the the lower Stubaital and a famous local peak known as Serles just  left of center.  

Over the weekend we did a short hike from our apartment to a the Raschbrunnen mountain hut.  

Return to Innsbruck is easy.  One option is to catch the train at the Kranebitten bahnhof. 

The other is to walk a couple hundred meters down the hill and catch the K bus, which we did.  It dropped us off 3 blocks from our apartment.  This is a great way to do point-to-point hikes.

Today (Thursday) was another holiday here.  Spring in Austria is one holiday after another.  These people know how to live.  We did a hike in the Karwendel Alps east of Innsbruck to the summit of the Stanser Joch at a bit over 2000 meters.  I love this kind of ridge hiking. 

A crown jewel of the area is the Achensee, a beutiful turquoise lake that sits in a saddle between the Inn Valley to the south (and out of view to the right of the photo) and Germany to the north.  

The Achensee features industrial-scale tourism, from the many guest houses to the small cruise ships that provide short excursions on the lake.  Still, it's a pretty place.  

It's going to be hard to leave.

RRFS and Utah Snow Ensemble Repairs

Both the RRFS and Utah Snow Ensemble have been down for a few weeks on weather.utah.edu.  These outages were due to changes in the formatting of model data provided the National Weather Service and ECMWF.  I didn't have the time to dig fully into it until today and at this point I think I've got things repaired.  We will see if the automatic processing works as we move forward.  

I noticed there are a few members of the Utah Snow Ensemble producing snow at Alta Collins in several days.  

There's always hope lol.