Tuesday, December 26, 2023

About That Alpine Snow

The northern and western Alps are generally off to a good start to the ski season, but there are some caveats.  Given our current snow drought, I thought we would have a look, focusing on the eastern Alps of western Austria and northeast Italy.  

Below is an analysis of total snow depth from the avalanche.report.  This is based on computer modeling and includes observations in colored circles.  Due to frequent northerly and northwesterly flow storms, snow depths are greatest (and impressive) at upper elevations along the northern Alpine Rim, especially near the Arlberg Pass (resort areas of Zurs, Lech, and St. Anton) and in the Karwendal Alps immediately north of Innsbruck.  Snow depth is lower, but still very healthy for this time of year, in the inner Tyrol (resort areas of Ischgl, Obergurgl, Sölden).   On the other hand, the Dolomites of Northeast Italy are really hurting.  The highest snow depth I could find there was 53 cm (about 21 inches).  This is because northerly and northwesterly flow puts them in the precipitation shadow of the Alps and often results in a warm downslope wind known as the Foehn (Föhn in German).   

Source: https://avalanche.report/weather/map/snow-height

On the other hand, there have also been some exceptional warm spells in the northern Alps and a quick look at the map above reveals that there is no snow at valley level in the Inn Valley and relatively little snow at lower elevations near the Arlberg.  For instance, there is only 67 cm reported in Warth (1490 m/4888 ft) and 40 cm (16 inches) in St. Anton (1285 m/4215 ft).  So, there is an incredible gradient of snowfall with elevation in that area from low amounts in the valleys to exceptional amounts at mid- and upper-elevations.  In St. Anton, for example, one goes from 40 cm/16 inches in town to 216 cm/85 inches at the Galzig Schneeestation (2025 m/6643 ft) and 352 cm/139 inches) at the Ulmerhütte (which is also right on the divide).  

A couple photos show the situation quite well.  The first is from just south of Obertsdorf, which is in the Bavarian Alps of Germany just north of the Arlberg, near an elevation of 800 m/2624 feet.  There is no snow at valley level.

Source: https://www.foto-webcam.eu/webcam/scheibenhaus/2023/12/26/0940

Similarly, the view looking south across the Inn Valley above Innsbruck shows no snow on the valley floor and in fact no natural snow cover even on north facing aspects up to about 1300 m/4265 ft. If you take a close look, you can see the artificial snow covering the lowest ski runs of the Patscherkofel just to the left of center. 

And it is still exceptionally warm.  In fact, at the time the photo above was taken, it was 4.5˚C/40F at the camera location, which is at 1921 m/6300 ft.  

The combination of heavy snowfall interspersed with warmth resulted in snow creep issues, such as this fissure that opened up on a ski run above St. Anton about a week ago.

Source: https://www.tt.com/artikel/30871819/pisten-brachen-weg-nasser-schnee-macht-tirols-skigebieten-zu-schaffen

The steep, grassy slopes of the Alps are also prone to glide avalanches, and they have been a big concern in the recent avalanche reports.  Glide avalanches typically occur on smooth surfaces, with the entire snowpack releasing down to the ground.  Melt water often lubricates the ground to enable this to occur, with glide cracks opening up over time as the snowpack begins to creek down the slope before catastrophically releasing. A friend sent me the photo below a few days ago of some impressive glide avalanches. I think these are from near Samnaun, just south of the Austrian border in Switzerland.

So, lots of snow at upper elevations in some portions of the Alps.  The analysis above shows quite nicely how variable snowpack and snow conditions can be with region and elevation in this part of the world. I suspect there are many people traveling over the Brenner pass from Italy to Austria in search of snow this holiday season.

2 comments:

  1. Thank you for (as usual) such an insightful and interesting analysis! Despite the significant high-elevation depths, the takeaway and tragedy is the increasing warmth at all elevations and lack of snow at the bottom. Global warming i.e. pollution doing its destructive work.

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  2. That inbounds glide slab is wild!

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