AVALANCHE UPDATE: Cold stabilizes snow conditions despite unfavorable winds, but heavy snow and temperatures above freezing forecast next week


Temperatures of about minus 15 degrees Celsius are stabilizing Longyearbyen’s snow-packed hillsides this weekend despite strong winds from the east that were a factor in last week’s avalanche, according to an assessment published Saturday morning by the Norwegian Geotechnical Institute.

About five millimeters of precipitation is expected between 9 a.m. Saturday and 9 a.m. Sunday which, combined with winds gusting to 47 kilometers an hour will result in drift accumulation primarily on the city’s westside mountains, according to the assessment at Norway’s avalanche warning system website. Longyearbyen was added to the system Wednesday.

“There is still little danger of avalanches to the settlement on the western side of the valley,” notes the assessment, which rates the overall risk during the next day as “low.”

Last Saturday’s avalanche – which buried ten homes, killed two people and forced 180 people to evacuate their homes – occurred on the eastside mountain of Sukketoppen.

The slide was triggered by one of the worst storms in Svalbard’s recorded history, with an intense amount of snowfall in a few hours accumulating highly unevenly due to easterly winds gusting to 120 kilometers an hour. But Ulrik Domaas, the geotechnical institute’s avalanche department leader, told TV2 strong gusts from the same direction today shouldn’t be problematic.

“Now we have enjoyed a period of relatively low precipitation and temperature changes that have been ideal for the snow in the mountains to stabilize,” he said. “It is not positive that it is now blowing from the east, but the wind will turn to a northerly direction during the day and not be a problem for snowslides. This information collected allows us essentially assume the snow is more stable than before.”

But Domaas told the TV station it’s still not safe for the 80 people still displaced from their homes to return.

“We have a weak layer in the bottom of the snowpack that is still quite unstable and that can be problematic,” he said. “We still think the probability of a naturally triggered huge avalanche is small. That means we think there needs to a extra factor, such as a skier on top of the snow, for a new avalanche to be triggered.”

The long-term forecast may also cause concerns, with up to 18 millimeters of precipitation and temperatures near or above freezing expected between Wednesday morning and midday Friday, according to the Norwegian Meteorological Institute. Winds are expected to be relative mild during that period, peaking at 20 kilometers an hour.

The storm that triggered last week’s avalanche produced about 21 millimeters of precipitation, but in a much shorter timespan.