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  INSTITUTE FOR SNOW AND AVALANCHE RESEARCH  DAVOS
               NATIONAL AVALANCHE BULLETIN NO. 72
                for Saturday, 19 January 2008
             issue date 18.1.2008, 18:30 hours
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  DELICATE AVALANCHE SITUATION AMID SIGNIFICANT WARMING
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CURRENT CONDITIONS

Thursday night on the northern flank of the Alps and in the 
Valais there was 5 to 15 cm of new snow; in Ticino and Grisons, 
less than 5 cm. During the day on Friday it was quite sunny, 
especially on the southern flank of the Alps. In the afternoon 
new cloudbanks moved in from the northwest. Midday temperatures 
at 2000 m were minus 2 degrees in northern regions and plus 1 
degree in southern regions. Generally light to moderate westerly 
winds prevailed, although they were very gusty. For the most 
part, only small sized snowdrift accumulations formed. 
The snow layering in the southern Upper Valais, in central 
Grisons, in the Engadine and in the Muenstertal is the least 
favourable. In these regions, faceted, very weakly consolidated 
layers are incorporated in the snowpack. Natural or human 
triggered avalanches continue to be possible in these places. 
Such layers are especially pronounced in areas near the tree 
line. On the southern flank of the Alps, the thick layers of new 
snow are consolidating incrementally. On the northern flank of 
the Alps there are still trigger-sensitive snowdrift layers near 
to the surface in places.


SHORT-TERM DEVELOPMENT

Friday night there will be a few centimeters of snowfall as part 
of a warm front sweeping through. The snowfall level will rise 
towards 2000 m. During the day on Saturday it will be 
increasingly sunny in southern regions to begin with, later on 
in the other regions as well. Moderate to strong westerly to 
northwesterly winds will prevail. Midday temperatures at 2000 m 
will be plus 2 degrees in western regions, 0 degrees in eastern 
regions and plus 4 degrees in the south. The freezing level will 
climb in western regions towards 3000 m.


AVALANCHE DANGER FORECAST FOR SATURDAY

Entire region of the Swiss Alps:
  Considerable avalanche danger (Level 3)
Through the rising temperatures and the radiation, the 
likelihood of avalanches being triggered will increase during 
the course of the day. 
In the southern Upper Valais, in northern and central 
Grisons, in the Engadine and in the Muenstertal, the 
avalanche prone locations are found on steep slopes in all 
aspects above approximately 1800 m. Small and medium sized 
natural avalanches are possible. Humming noises are 
indications to attentive backcountry skiers and freeriders of 
the delicate situation. Extensive experience in assessing the 
avalanche hazards is imperative. 
On the northern flank of the Alps, in the Lower Valais, in 
the northern Upper Valais, in Ticino, in Val Calanca, in Val 
Moesa, in Bergell and in Puschlav, the avalanche prone 
locations are found on steep slopes in all aspects above 
approximately 2000 m. Slab avalanches can be triggered by 
single backcountry skiers and freeriders most easily in those 
places where the snowpack is of substandard thickness.

In the western regions on the northern flank of the Alps below 
about 2000 m in particular, moist sluffs and wet snow avalanches 
can be expected in the course of the day.


TREND FOR SUNDAY AND MONDAY

Sunny weather is expected on both days and in the mountains it 
will be quite mild. The avalanche danger is subject to a mild 
cycle of daytime warming.