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  INSTITUTE FOR SNOW AND AVALANCHE RESEARCH  DAVOS
               NATIONAL AVALANCHE BULLETIN NO. 77
           from Monday, 12 February 2007, 18:30 hours
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  FURTHER INCREASING AVALANCHE DANGER WITH STRONG NORTH-WESTERLY 
WIND AND FRESH SNOW
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CURRENT CONDITIONS

Monday was mostly very cloudy, and the showers persisted in the 
west and north. There were some bright spells in the south and 
Upper Engadine. Since Saturday morning the following amounts of 
snow have fallen: Vaud and Fribourg Alps, Lower Valais and Goms 
30 to 50 cm; remaining northern flank of the Alps, Gotthard 
region, north-west Ticino, Praettigau to Samnaun 10 to 30 cm; 
other places only a few centimetres. On the southern flanks of 
the Alps it remained dry. Midday temperatures on Monday at 2000 
m were between plus 1 degree in the north-west and minus 2 
degrees in the south. The snowfall level rose temporarily to 
approximately 2000 m. The moderate to strong west to south-
westerly wind was very gusty. 
Wind has transported snow from the vicinity of ridge lines, so 
that the snow surface there is hard. The fresh snow layers and 
the layers of older new snow and wind-deposited snow are poorly 
bonded.


SHORT-TERM DEVELOPMENT

The showers will continue. By Tuesday evening the following 
quantities of fresh snow are expected: northern flanks of the 
Alps, western Lower Valais, northern Valais, Gotthard region 30 
to 50 cm; elsewhere 10 to 30 cm. The south has sunny spells. The 
snowfall altitude drops during the night to approximately 700 m. 
Midday temperatures at 2000 m falls to about minus 6 degrees. 
The wind direction will change to north-westerly. The wind will 
be strong to gale force. 
Further snow drift accumulations will form, some of them large, 
mainly in the regions with fresh snow.


AVALANCHE DANGER FORECAST FOR TUESDAY

Northern flanks of the Alps; Valais; Gotthard region; northern 
Surselva; Flims-Untervaz; Praettigau; Silvretta; Samnaun:
  Considerable avalanche danger (level 3)
The avalanche prone locations are wind-loaded slopes of all 
aspects. They are above approximately 1800 m on the northern 
flanks of the Alps and above approximately 2000 m elsewhere. 
Natural avalanches can occur. In the west in particular these 
can be medium-sized avalanches and, in isolated 
circumstances, they can endanger exposed parts of 
transportation routes. Caution and extensive experience in 
the assessment of avalanche danger are required.

Remaining areas of the Swiss Alps:
  Moderate avalanche danger (level 2)
Avalanche prone locations are to be found, in particular, in 
gullies and bowls of all aspects. In the rest of northern 
Ticino and the rest of Grisons, excluding the southern 
valleys, these locations are above approximately 2000 m. With 
the onset of showers and the transportation of snow by the 
wind, the avalanche danger will increase during the day. 
Avalanches can be triggered by a single person. 
In central and southern Ticino and the Grisons southern 
valleys, the avalanche prone locations are to be found above 
approximately 2400 m.

Especially in the west and north, isolated small wet snow slides 
can occur on all aspects below approximately 1800 m.


TREND FOR WEDNESDAY AND THURSDAY

On Wednesday small quantities of snow will continue to fall in 
the west and north, and the weather will become milder. It will 
brighten up on Thursday. The avalanche danger will decrease 
slowly from Thursday.