Fresh snow has smothered the Alps in the remote Swiss town of Davos, which was put on high alert on the eve of the important gathering of business leaders, politicians and representatives from non-government organisations.
A host of world leaders -including US President Donald Trump, Theresa May, India’s prime minister Narendra Modi, French President Emmanuel Macron and Canadian PM Justin Trudeau are set to attend the event.
But the SLF Institute for Snow and Avalanche Research in Davos warned a broad band of the mountainous country was under Level 5 avalanche danger, the highest on a 1-5 scale.
It said: “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.”
Snow slides could be deep and large, it added, posing danger to exposed settlements and transit routes.
The accumulation of snow is the highest since 1999 and authorities have evacuated two dozen people from homes most at risk.
The World Economic Forum takes place at the upmarket ski-resort between January 23 and 26.
But Mr Trump’s attendance was in doubt on Monday as the US government shutdown stretched into a third day.
White House spokeswoman Sarah Sanders said the departure of a high-profile US delegation for the conference has been delayed.
Slated to lead the delegation were Treasury Secretary Steven Mnuchin and Commerce Secretary Wilbur Ross.
Mr Trump is scheduled to depart later in the week for a speech in Davos on Friday, the last day of the four-day global conclave of political and financial movers and shakers.
The World Economic Forum said it still expected the US President to attend.
But leaders could face difficulty getting around due to the snow. Zermatt in southwestern Switzerland remained cut off by road and rail.
Access roads are still open as crews use controlled explosions to reduce the chance of slides. The sun is due to come back out on Tuesday.
A town spokeswoman said a helicopter air bridge that had been ferrying people in and out of the popular ski resort was out of action because of bad weather.
A helicopter rescue team had to fly a pregnant woman out of the town on Elm in Glarus canton where snow drifts had cut off roads as she went into labour. And, at lower elevations steady rain was causing local flooding.
The ski resort is due to play host to a series of crunch meetings at the World Economic Forum.
Mrs May andMr Trump are expected to hold a bilateral meeting on the margins of the Swiss summit.
A Number 10 spokesman said: “The Prime Minister will have a bilateral meeting with President Trump in the margins of the World Economic Forum at Davos in Switzerland next week.”
There had been rumours that the pair would not meet after the US president canceled a trip to open the American embassy in London.
However, US Secretary of State Rex Tillerson today reaffirmed the US’s commitment to the “special relationship” with Britain amid reports of strains between London and Mr Trump’s administration.
Following talks in London with Foreign Secretary Boris Johnson, Mr Tillerson said the US continued to “treasure” its transatlantic ties with the UK.
He said: “We also view this as the special relationship. It has been and will be.”
“We spend a lot of time talking about the world’s problems. Sometimes we forget about the importance of our own relationship.
“We treasure this relationship. I treasure Boris’s relationship with me personally.”