Contrasts Across the Alps

In the previous post (An Optimistic Snow Forecast) we discussed a developing storm in the southern European Alps, with snowfall developing in the southern Limestone Alps today and becoming heavy through Saturday.

It's worth taking a closer look at the contrast that exists across the Alps during these situations, as when the southern Alps have great upslope, the northern Alps have downslope winds, known as Foehn.

I'm going to use images from two web cams from the great https://www.foto-webcam.eu/ web site. The first is from San Cassiano near Alta Badia in the Dolomites.  The cam faces roughly westnorthwest.  The other is from Seegrube in the Nordkette range above Innsbruck.  The cam faces roughly south and looks toward Brenner Pass and the crest of the Alps.   

Source: maps-for-free.com

With flow from the southern half of the compass, San Cassiano is on the windward side of the Alps for this storm.  Prior to the storm, on December 1st. there was little to no natural snow evident in the area.  

Things are beginning to change, however, and snowcover is evident today, with more on the way.

Meanwhile to the north of the Alps, downslope foehn is developing.  The series of images from Seegrube shows significant change from yesterday when cloud cover filled the Inn Valley and also lingered on the Alpine crest (top photo below).  Overnight, the low clouds cleared out as downslope Foehn developed.  Clouds on the Alpine crest deepened with the increasing southerly flow.  By today, snow was falling on the Alpine crest and spilling over into the mountains and Wipptal (the Wipp Valley, which descends from Brenner Pass), but one can see some sun in Innsbruck. 

This is a very common occurrence in the Alps with stark contrasts from one side to the other during storms.  It does work both ways.  There are situations when the north side gets heavy snow and the south side is dry (see Stau Storm).  In some seasons, one side of the Alps sees more storms than the other, and a quick trip across or under the Alps can lead to better (or worse) snow. 

Knowledge is power, but weather knowledge is powder power.