snow is not the same Snow. He is by definition a mixture of ice crystals, water, water vapor and air in particular. This is no surprise. Interestingly, however, that the snow water content, depending on the damp and stronger again. This depends to a fall on the moisture content of air in the snow and off to the other by the temperature and humidity conditions in the cloud. The temperature at the soil affects the moisture content in the snow barely, only when it is there.
problem - snow forecast
The current weather models to calculate the amount of precipitation in the unit mm (= liters / square meter). But what about snow removal services have like the snow in mm (water equivalent) should be? Also Average consumer is interested in more for the winter snowfall in cm as for his molten equivalent in mm or liters per square meter.
Experience and a few scientific studies have shown that one can convert the mm in the model with the 10:1 rule in cm New Snow: 1 mm water equivalent of snow thus means 10 mm. It is assumed that the snow falls with a density of 100 kg / m³. However, studies have shown that quite densities between 20 kg / m³ (very dry and light snow) occur and up to 300 or more kg / m³ (wet snow). This would therefore result in conversion ratios from 50:1 to 3:1.
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| Nassfeldpass yesterday evening |
Jenna and deep snow
The last Adriatic depression has brought the south and east of Austria a few cm of fresh snow. Thus while in Vienna nearly 10 cm, 15 cm in Graz and Klagenfurt in 20 cm of fresh snow. In between there were some more (Fischbach 18), some less / Eisenstadt with 10). And depending on the temperature in the lowest layers of air (Schmelzungsgrad the snow) the snow was wet or dry.
wettest (densities of 100) had fallen in the Ried (first rains), the driest (By 40 to 70) in the Southern Alps (snow consistently below 0 degrees).
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One problem with the calculation of the snow density is the time of measurement. In principle, new snow is measured only once daily, in some places the snow is probably already 12 hours old, gone with the wind and set. Thus, the densities calculated for mountain (Kredarica 180, Villach Lape 140) more than to doubt. Also, the fit for St. Pölten not in the picture. In contrast to the normal rainfall measurement is the Measurement of snow fraught with more errors, but still "real". A blanket of snow is what it is inhomogeneous and in the rarest case, therefore, is a point measurement representative of the entire region.
No traffic problems
again back to the snow event. Even if 10 cm of snow increase the city of Vienna often presents problems, which this time was not the case. Wien.orf.at wrote this morning:
has over night it snowed in Vienna up to four inches. There have been no problems in the early traffic. The winter is the 1,200 men and 380 clearance vehicles in use. [...] Even with the ÖBB there were no problems so far. Almost all the trains are on time on the road.
But it should be interesting to see what delivered the next low-pressure areas in addition to fresh snow in the coming days. The south-western weather that is still there remains this week, only towards the weekend there are signs of a warming.
JRC (06) calculated via wetter3 until Friday morning in particular, again south of the Alps is a nice package, the Maximim the snowfall is in Europe but elsewhere: in Poland and Belarus, as well as in the Massif Central is the winter is very thick:
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| GFS forecast to Friday 06 UTC (96h) |
The European model (Alpine section) has also in it for the main Alpine ridge at the 40 cm of fresh snow.
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| ECMWF forecast until Friday morning (96 hours) |
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Sources:
webcam Nassfeld (1): Avalanche Warning Service Kärnten
amounts of new snow: UBIMET
-fallen snow seal + Graphics graphics (2 +3): alpen.wetter (Austria Map taken from bergfex.at)
snow forecasts: wetter3.de (4); bergfex.at (5)
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