Convective Graupel Showers

Spring and summer mountain thunderstorms can produce precipitation that sometimes includes graupel or small hail that can penetrate well below the freezing level.  

A good example happened yesterday over the Nordkette ridge just north of Innsbruck.  I had a great view of it from my office. The storm popped up around 2 PM local time.  The streaky virga in the right of the photo below srongly suggested the presence of graupel or small hail.  A bit farther to the west (left in the photo) though was less precipitation and even a bit of sun peaking through a hole in the clouds.  

After a couple of rumbles of thunder, the storm was over quickly.  Light graupel accumulations were evident where the cell was, with accumulations reaching down to about 1900 meters, whereas the high ridge farther west, which reaches over 2300 meters, was still snow free.  

A web-cam on the portion of the ridge that received precipitation showed some graupel accumulation at 1900 meters.  

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

It didn't take long for the graupel to melt once the storm was over, but it was good entertainment while it lasted. 

I Have Seen the Future

One of the great things about coming to Europe to work is getting exposed to the latest and greatest modeling systems for operational weather prediction.  

Modeling systems for operational weather prediction in the United States has stagnated now for several years.  The last major upgrade was when the Global Forecast System (GFS) upgraded to the Finite–Volume Cubed Sphere (FV3) dynamical core in 2021.  Beyond that, upgrades have been  incremental, with no major changes to the grid spacing of the GFS (13-km) or the HRRR (3-km).  The GFS Ensemble (GEFS), Short-Range Ensemble Forecast System (SREF), and High Resolution Ensemble Forecast system (HREF) have aged and are no longer cutting edge. 

Meanwhile in Europe, both numerical and artificial intelligence weather prediction systems (NWP and AIWP respectively) are advancing rapidly.  Readers of this blog are likely well aware that the European Center for Medium-range Weather Forecasting (ECMWF) ensemble has the highest resolution (9 km), most members (51), best data assimilation, and best statistical performance of any operational, global, numerical modeling system in the world.  ECMWF is also also at the forefront of AIWP and now has their Artificial Intelligence Forecast System (AIFS) ensemble running four times a day.  

But European countries are also pushing the frontiers of limited-area modeling systems that forecast for a specific region.  For example, Meteo Swiss runs an operational, 11-member, 1-km ensemble eight times a day with forecasts out to 33 hours.  They also run a 21-member, 2.1-km ensemble four times a day with forecasts out to 120 hours (see https://www.meteoswiss.admin.ch/weather/warning-and-forecasting-systems/icon-forecasting-systems.html). These forecasts are produced using the ICON model, which was originally developed at the Max Planck Institute for Meteorology in Germany.  The ICON is also used by the German Weather Service.

Here at the University of Innsbruck, I have access to an experimental version of the ICON model run by the Deutscher Wetterdienst (DWD; German Weather Service) at 500-meter grid spacing.  NWP models run at such grid spacings are sometimes called large-eddy simulations (LES) rather than mesoscale simulations because they are beginning to resolve the large eddies that are found in the boundary layer, the portion of the atmosphere that interacts directly with the Earth's surface.  A model run at 500-meter grid spacing also better resolves the fine-scale terrain in mountains regions, which is particularly important in the Alps where glacier-carved mountain valleys are quite narrow.  

Let's look at last night's 6-hour forecast from the 500-m ICON valid at 0600 UTC or 8 AM local time this morning.  The plot below shows the wind (vectors with color fill for speed in meters per second) at 2000 m elevation (relative to sea level).  Terrain elevation above 2000 m is indicated by grey shading. The pattern is characteristic of what are known here as föhn, a strong wind that affects the northern Alps during southerly flow.  In the Innsbruck area, the föhn acclerates as it moves northward through Brenner Pass and down the Wipp Valley.  At this 2000 m elevation, that strong flow eventually moves over Innsbruck and encounters the Karwendel Alps, leading to flow splitting on their southern (windward) side and a wake on their northern (leeward) side.  Locally strong föhn can also be seen in and north of other Alpine Valleys in the region.  

Source: University of Innsbruck

A cross-section from the ICON taken from south (left) to north (right) down the Inn Valley illustrates the vertical structure of the föhn in this forecast.  Locations identified in the cross section include Brenner Pass (BRE) and Innsbruck (IBK).  Note in particular that the strongest föhn flow becomes elevated just upstream of Innsbruck (near EUR) and ultimately rises rapidly whe it encounters the Nordkette ridge of the Karwendal Alps to the north of Innsbruck.  

Source: University of Innsbruck

The cause for the detatchment of the föhn flow from the surface as it approaches Innsbruck is the formation of a nighttime old pool over the Inn Valley.  At night and in the morning, the föhn often rises over this cold pool, although there are times it can "break into" the cold pool, resulting in strong south winds at the surface in Innsbruck.  This is an important forecast problem for the region, including for the local airport, as it affects runway flow direction and the elevation of föhn related turbulence.

How did that forecast verify?  Quite well.  Below is a time-height section of winds over Innsbruck observed with a wind lidar.  The time-height section is for a 24-hour period (time increases to the right).  I've added a red line corresponding to the time of the forecast above.  Note how in the left half of the diagram, the föhn frequently extended to the ground.  Then, just prior to and after 0000 UTC (0200 local time), winds over Innsbruck weakened.  However, by 0600 UTC the southerlies aloft increased once again, resulting in a structure similar to that above with light flow at low levels but strong flow aloft.  

Source: University of Innsbruck

Readers of this blog with a strong interest in snow might also be interested in seeing the corresponding 500-m precipitation forecast.  Validating this is a bit more difficult given the poor radar coverage in the Alps, so I provide it simply for entertainment purposes.  

Source: University of Innsbruck

Enjoy a look at the future.

Walking

This is my second long-term visit to Innsbruck and in both cases my body went through a real transformation due to the amount of walking that one does here.  I would guess that I average walking 10 km a day, scattered around from morning to night.  It's a great way to keep the body in motion.  

And Innsbruck is a wonderful place to walk.  The town in interesting and many places historical.  There are views everywhere.  The old town area is car free, but even elsewhere, the road traffic is moving slowly and respectfully.  Just look at a crosswalk and drivers will stop.  Austrian law is very protective of pedestrians, but drivers here are also very pedestrian aware because everyone here walks some.  

One can also hike right from town, accessing mountain huts on the Nordkette north of town or if you are so inclined, ascending all the way to the ridgeline about 2000 meters above town.  Public transit is exceptional so one can access hikes in the surrounding region easily or use public transit to enable one way hikes with a bus return.  Believe me when I say that high-quality summertime public transit would completely transform recreation in the central Wasatch by enabling many outstanding point-to-point through hikes. 

One of my favorite destinations for a casual walk or hike is the Hungerburg neighborhood that sits on a ledge about 300 meters above Innsbruck.  I get a nice little climb in when I go there taking any number of routes.  There is the direct route following cobbled roads, pedestrian paths, and trails, which takes about 45 minutes, or more circuitous options involving urban walking and trail hiking that might take an hour or two.  I just go with what feels right and return via bus or funicular.

The route I did today merges the best of everything.  It starts with a level section along the Inn River.  I realize seeing this river every day how much I miss water living in Utah.  

Then there's about a 300 vertical meter ascent through managed forests that occaisionally open up for a quick view.

Once at Hungerburg, there's a wonderful view of Innsbruck.    

I often return to the valley floor via the Hungerburgbahn funicular.  Below is the entrance.  A walk up ticket is an overly expensive 7 euro, but fortunately I get unlimited free access with my ski pass.  

One reason I like to return via the funicular is that it ends near the Innsbruck Old Town and I enjoy walking through it to get back to our apartment, especially in the morning when there are no crowds.

There is a gelateria that is open early if one is inclined to have ice cream for breakfast.  I showed great will power not stopping this morning, although I ultimately had a schokomuffin while walking to the office.  So many bakeries.  So little time.  

The NWS Is Hiring

What is probably the biggest hiring action in modern National Weather Service history is now underway.  If you are looking for positions with that agency, government boilerplate with links are below.  

The DHA announcements for the Standing Register Meteorologist, GS-1340-05/07/09 positions have been posted. The announcements are set to open May 1, 2026 - September 30, 2026.

PR-424133 ("Harder to Fill" Locations):

Job Announcement # (DHA): NWS-26-12947704-DHA

• https://www.usajobs.gov/GetJob/ViewDetails/867259300

PR-424134 ("East" Locations):

Job Announcement # (DHA): NWS-26-12947756-DHA

• https://www.usajobs.gov/GetJob/ViewDetails/867260400

PR-424136 ("West" Locations):

Job Announcement # (DHA): NWS-26-12947773-DHA

• https://www.usajobs.gov/GetJob/ViewDetails/867260700

Tyrol in Spring

Much like Utah, the Alps offer up a tremendous diversity of recreational opportunities in the spring months due to the large elevation differences and diverse microclimates. 

The Inn Valley and the south-facing slopes of the Nordkette ridge immediately north of Innsbruck are green with just a few patches of snow hanging in the high elevations.  One can get off work and go for a hike to one of several mountain huts or alms on the lower- and mid-elevation slopes of the Nordkette.  Directly above our apartment we can climb about 550 vertical meters to Umbruggler Alm for lunch, dinner, or strudel.  

Similar to the Salt Lake Valley, the views right now are of green valleys and snow capped mountains.  One difference is that things will probably stay green in the low elevations through the summer because it actually rains here.  

The next day I skied at Ischgl, which reaches to about 2800 meters elevation, and is fully interconnected with Samnaun in Switzerland.  Below shows the valley route from the top of the ridge that divides the two resorts down to the village of Samnaun.  

Once the snow softened a bit, we did a good deal of off-piste skiing on the Ischgl side.  This is below the Piz Val Gronda cable car.  I jokingly called this run "Little Snowbird." 

One reason for that is my friend Samu calls this one "Little Alta."

A highlight for the day was skiing down a very long and completely untracked gully that skied like butter.  Spring snow can be wonderful like that.  The bottom though got a little thin.  We slalomed through the rocks and then had to do a mixture of hiking and skiing to get out.  

Ischgl is a hard partying resort with a skiing problem.  At 2300 meters they have a concert stage setup for their Top of the Mountain concerts. 

If you miss Frank at Alta, this might be a good fall back.  I grabbed that photo off the web.  My multi-resort pass is not good on Ischgl concert days, not that I care.   

Source: https://www.top.tirol/news-tourismus/konzertreihe-bringt-ischgl-millionen

Finally, when the knees are cranky, a great thing to do from Innsbruck is take a 40 minute train ride to Seefeld.  The train climbs up the steeply sloped north wall of the Inn Valley and offers up great views.  

You'll find many older Tyroleans on the train as there's a lot of low angle walking in the Seefeld area.  You can walk for many miles if you like or just a few.  There's plenty of views to be had from the open areas around Seefeld.  One of the more famous views is of the Seekirche Catholic Church right on the edge of town.  

Secrets of the Greatest Snow on Earth at the University of Innsbruck

I'm approaching the half-way point of our stay in Tyrol.  One of my responsibilities as a Guest Professor is to present a "public lecture" as a way to introduce myself to the Department of Atmospheric and Cryospheric Sciences as well as the wider University community.  I decided to adapt my "Secrets of the Greatest Snow on Earth" talk to a Tyrolean audience.  

Although the talk had some similarities to the versions I've given in Utah, significant modifications were needed.   The Greatest Snow on Earth slogan is well known in North America, but most people in Innsbruck have never heard of it.  I had to introduce the slogan, and how it is put on everything from web sites to license plates, providing an opportunity for a little humor by imagining what might have happened if Tyrol had come up with it first.   

To introduce everyone to Utah skiing I decided to compare the history of skiing in Austria with Utah. There are some great parallels here.  Austria has a very long and rich history with Alpine skiing, with St. Anton and the Arlberg region known (and marketed) as the "cradle" or birthplace of Alpine skiing.  One reason for this is that Hannes Schneider, who was born in the village of Stuben in the Arlberg, was a pioneering Alpine skier who developed the Arlberg technique there, a system for teaching skiers how to progress from wedge to parallel skiing that revolutionized ski instruction in the early 20th century.  

For comparison, Utah has a very long and rich history with deep-powder skiing, especially at Alta where many people, including the Alf Engen, Dick Durrance, and Junior Bounous were developing the techniques to ski the steep and deep.  Here are a couple of slides discussing these two rich regional ski histories.  

The turnout was great with probably about 100 people attending.  And they really know how to celebrate and make a visitor feel welcome.  After answering questions for about 15 minutes the regional wines and local beer were rolled in and we had a great social hour. 

Much thanks to the Department of Atmospheric and Cryospheric Sciences and the Mountain Regions Research Area for hosting the event.