Some incredible snow totals continue to come in from the south side of the eastern Alps. The biggest increase in the Height of Snowpack (HS) that I could find was at the Porzehütte, an Austrian Alpine Club hut in the Carnic Alps just north of the border of Italy. I grabbed the screen shot below fortuitously when they peaked at around 2.34 meters, which represents more than a 2 meter increase in less than 24 hours.
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| Source: lawis.at/station |
I don't know how to access tabular data to get precise numbers for total water equivalent, but a guesstimate from the graph yields about 400 mm, so we're talking some serious concrete with 20% water content if those numbers are accurate.
The Carnic Alps, as well as the Julian Alps and Dolomites to the south, are one of the wettest parts of the Alps and prone to heavy precipitation. An analysis of average annual precipitation in the Alpine region shows the highest values along the northern and southern "rims" of the Alps. In the central and eastern Alps, precipitation actually decreases as you move into the Inner Alps, despite the terrain getting higher.
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| Average annual precipitation (mm) in the Alpine Region. Source: Isotta et al. (2013). |
There are also two precipitation "hot spots" on the southern rim. The first is in the Ticino, Lombardia, and Piemonte regions of Switzerland and Italy. The second is in the Dolomites, Julian Alps, and Carnic Alps of Austria, Italy, and Slovenia. These precipitation hot spots are produced by flow interactions with the Alps and the surrounding mountain ranges, which focuses vapor transport and precipitation dynamics in these areas.
In addition, these are areas that receive the greatest fraction of their precipitation on days with moderate to high precipitation intensity, so their precipitation climatology is biased to big events.
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| Fraction of precipitation from moderate to high precipitation intensity days. Source: Isotta et al. (2013). |
In contrast, moderate to high precipitation intensity days produce a lower fraction of the precipitation along the northern rim. Thus, the southern rim and hot spots get their precipitation when Mother Nature hits home runs (big events), whereas the northern rim scores with lots of base hits (lots of smaller events). Note that this doesn't mean that the northern rim doesn't see extremes, because it does, but it tends to see more frequent smaller events than the southern rim.
A few photos of this event from @weathertoski are provided below. The area is still seeing snow and will see periods of snow, possibly heavy again on Tuesday, until Wednesday. Impressive!
Potentially historic snowfalls for some southern parts of the Alps: https://t.co/PGoKdcOhGN pic.twitter.com/CJbv9b51Gj
— weathertoski (@weathertoski) December 6, 2020
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