Sunday, February 10, 2019

Dodging the Foehn

After yesterdays splendid ski tour, I thought I would do a short day of alpine today (Sunday) and get a little work done in the afternoon.

There was, however, a challenge as today was forecast to be a Foehn day.  The Foehn is a strong downslope wind that affect the northern Alps during periods of southerly cross-barrier flow.  Think of it as the Alpine equivalent of Utah's "Canyon Winds", although they are more frequent.

Owing to the surrounding topography, Innsbruck is quite exposed to strong Foehn.  Innsbruck lies in the deep Inn Valley, which runs predominantly from west to east, with the Inn river flowing eastward.  Although surrounded by high mountains, the Wipp Valley lies due south of Innsbruck and represents a low-elevation corridor that connects with the Alpine Divide at Brenner Pass, where the border to Italy lies.

Map background source:
During Foehn, strong winds extend down the Wipp Valley to Innsbruck.  They also have a strong influence on the Patscherkofel, the easiest ski area to access from my apartment, as it is immediately adjacent to the Wipp Valley.

I'm not expert on the local meteorology around here, but enough people told me to avoid the Patscherkofel during Foehn that I never even considered going there this morning.  Instead, I went to Axamer Lizum, which is probably the best ski area I can access on a free bus anyway.

Turns out it was a good call.  Below is a seven-day time series of wind speed and gusts from the top of the Patscherkofel (these are provided by ZAMG, the Austrian Weather Service).   Southerly flow at this location began late yesterday (1800 LST) and ramped up overnight and today.  So far, the peak gust of just over 120 km/hour (75 mph) was at noon.

Source: ZAMG
The Patscherkofel gondola doesn't reach the summit where those observations are taken, but I noticed as soon as I got back to Innsbruck that the bus stop for the line going to the Patscherkofel ski area said the gondola was closed due to the weather.  Yes, they provide that information on electronic signs at the bus stops.

Meanwhile, in Innsbruck at the University of Innsbruck, winds really picked up after noon, with a peak gust of just over 75 km/hour (45 mph).  The local flow there is westerly, although the origin of the winds is the south.

Source: ZAMG
I had no problem skiing at Axamer Lizum this morning.  The timing was good (before the flow really ramped up) and it was less exposed than the Patscherkofel.  I was, however, able to observe some of the effects of the Foehn.  The Panorama below is taken looking toward the ENE.  Innsbruck lies in the deep valley at left and the flow is mainly from right to left.  To the right of the prominent peak just lef of center, one can see low clouds that have spilled across Brenner Pass into the Wipp Valley.  These clouds eventually dissipate as the flow descends into the Inn Valley, warms, and dries.  However, there is a band of clouds over the Nordkette range immediately north of Innsbruck.  These clouds persisted all morning and they were the only clouds along that entire range, including its extension further west, which can't be seen in the photo.  I suspect that the Foehn winds were riding abruptly on the south face of the Nordkette, leading to the cloud formation either due to that area seeing the strongest incident flow and/or the flow from the Wipp Valley being a bit cooler and moister since it traversed a lower portion of the Alpine Divide (i.e., Brenner Pass and the immediate surrounding area).  My colleagues can correct this hypothesis tomorrow if it is wrong :-).  

Getting back to skiing, I rode the chair today that ascends the Bergitzköpfl, which services ungroomed terrain on the east side of the valley and provides a view of most the terrain at Axamer Lizum.  One can see the funicular snaking to the top and several chairlifts.    

Although the light was terrible when I took those photos, the filtered sun provided good light for most of the morning, with no major impacts of the Foehn, although I did noticed that they cancelled their hot air balloon event.  


  1. how do those bubble chairs work with foehn winds?

    1. Keine Ahnung (no idea). I haven't been there when the winds have been blowing hard.