The exclusive ski resort was snow-bound on Monday after the heaviest precipitation in two decades.
“In the last six days, 159 centimetres (63 inches) of snow fell on Davos (...) a fall that we observe only every 20 years,” Switzerland’s Institute for the Study of Snow and Avalanches said in an evening bulletin.
“From Monday evening until the end of the snow overnight, an additional 20 to 40 cm will be added,” the Institute said, evoking an “exceptional” situation.
Heavy snow has been blanketing Davos for days. After a brief lull on Monday, large flakes began to fall in the early afternoon, disrupting traffic and threatening to block the landing of VIP helicopters.
An economist registered at the forum told AFP it took two hours to drive the last 12km (7 miles) approaching the resort.
Trains were more crowded with official Davos delegates, who usually take limousines and special shuttle vehicles to the week-long forum.
In the centre of Davos, participants preferred to walk rather than take the shuttles, which were slowed down by roads resembling skating rinks.
Businessmen slipped over on icy patches as snow ploughs roamed the streets, with the snow returning as fast as the machines could clear it.
The streets are not salted in Davos, to protect the environment.
On Sunday, the snowfall had already disrupted the road traffic and temporarily cut the railway line leading to the ski resort.
With the weather forecast to clear on Tuesday, organisers are hoping transport will start to operate more smoothly and will be running without a hitch by the time US President Donald Trump arrives on Friday to give the closing address.
However, so much snow has built up on the slopes surrounding Davos that avalanches remain a danger.
A bulletin from the SLF Institute for Snow and Avalanche Research in Davos showed a broad band of the mountainous country under Level 5 avalanche danger, the highest on a 1-5 scale.
“Fresh snow and snow drift accumulations are prone to triggering (avalanches). Until late in the night a large number of natural avalanches are to be expected,” it said.
Local officials said on Monday they had evacuated two dozen residents from vulnerable areas while crews used explosives to reduce dangerous build-ups on some slopes above the town.
“When Trump comes on Friday it is far from obvious whether he will be able to use a fleet of large helicopters to land in Davos,” said a source close to the organising committee. “Large helicopters increase the risk of avalanches.”
Meanwhile, heavy snowfall in France has led to the evacuation of more than 100 chalets in one of France’s best known ski resorts near Mont Blanc because of avalanche risks.
“The situation is extraordinary: we’ve had the equivalent of five months of precipitation in just 45 days,” the mayor of the Chamonix resort, Eric Fournier, told AFP, adding that such snowfall “occurs once every fifteen years”.
Over 1,000 residents had been contacted by midday, Fournier said: “We’re asking them to stay inside and to close up shutters on the sides exposed” to potential avalanche flows.
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