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  INSTITUTE FOR SNOW AND AVALANCHE RESEARCH  DAVOS
               NATIONAL AVALANCHE BULLETIN NO. 117
           from Saturday, 24 March 2007, 18:30 hours
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  PARTICULARLY ON THE NORTHERN FLANK OF THE ALPS STILL 
CONSIDERABLE AVALANCHE DANGER
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CURRENT CONDITIONS

On Saturday in the Valais and in southern regions it was quite 
sunny. In northern regions there were increasingly sunny 
intervals during the course of the day. Light easterly winds 
prevailed. Midday temperatures at 2000 m were minus 8 degrees in 
the north and minus 4 degrees in far western regions and in the 
south. 
Since Wednesday 30 to 50 cm of snow has fallen in the northern 
Prealpes. In Lower Valais and along the remaining northern flank 
of the Alps it snowed about 15 to 30 cm, south of these regions 
somewhat less. The new snow is consolidating, yet particularly 
on north facing slopes is still loosely packed. In exposed 
places there are especially dangerous snowdrift accumulations. 
The weak snowpack fundament is prone to triggering in places, 
particularly in inneralpine regions.


SHORT-TERM DEVELOPMENT

On Sunday it will be overcast in southern regions and a bit of 
snow is expected. Elsewhere it will be quite sunny. During the 
course of the day, cumulonimbus clouds will form and isolated 
showers are possible. The midday temperature at 2000 m will rise 
to minus 2 degrees in northern regions. In southern regions it 
will be about minus 4 degrees. Moderate southeasterly winds will 
prevail and will increase in strength during the day. 
The new snow of recent days continues to consolidate.


AVALANCHE DANGER FORECAST FOR SUNDAY

Northern flank of the Alps with the exception of Urseren; also 
northern Praettigau and western Silvretta:
  Considerable Avalanche Danger (Level 3)
The avalanche prone locations are on steep slopes in all 
aspects above approximately 1800 m. Single persons can 
trigger avalanches. Snowdrift accumulations are especially 
dangerous and often difficult to recognize, since they are 
covered over by snow. Areas adjacent to the ridge line must 
be judged especially critically. Experience in the assessment 
of avalanche danger and careful route planning are essential.

Valais; Urseren; northern and central Ticino; Grisons with the 
exception of northern Praettigau and western Silvretta:
  Moderate Avalanche Danger (Level 2)
In the Valais, in Urseren and in Grisons except for Calanca, 
Misox, northern Praettigau and western Silvretta the 
avalanche prone locations are on steep slopes in all aspects 
above approximately 2000 m. Areas adjacent to the ridge line 
are especially treacherous due to the snowdrift. Particularly 
in inneralpine regions, isolated fractures down to the old 
snow cover are possible. Prudent route selection is 
important. 
In the central part of the southern flank of the Alps the 
avalanche prone locations are primarily on west to north to 
east facing steep slopes above approximately 2200 m.

On steep sunny slopes frequent snow slides can be expected. In 
lower lying altitude zones, full depth wet snow slides on the 
ground continue to be anticipated.


TREND FOR MONDAY AND TUESDAY

It will be predominantly sunny. During the afternoon, 
cumulonimbus clouds and isolated showers are possible, 
particularly in southern regions. The avalanche danger will 
continue to diminish.