Northeasterly 'bise' wind prolongs Swiss winter

The bitter cold conditions brought by the bise, a northeasterly wind, are set to remain until Thursday, when warmer temperatures are finally expected to bring relief to winter-weary Swiss.

Gusts were clocked at up to 90 kilometres an hour over Lake Geneva on Monday and reached 97 km/h in Bienne, according to MeteoSwiss, the national weather office.

They dropped to 60 km/h in Geneva on Tuesday morning and were recorded at 86 km/h in Bienne, Ludwig Zgraggen, a MeteoSwiss expert in Zurich, told Swisster.

The wind raised the chill factor to temperatures already well below zero, as Switzerland suffered from its fourth major bout of freezing weather this winter.

A bise of this magnitude usually occurs every five years, Zgraggen said.

This latest epidode, which starting blowing on Sunday “will go to Thursday, which is longer than usual,” Zgraggen said.

The bise occurs when there is high pressure over the British Isles accompanied by low pressure in the Italian area of the Mediterranean, he said.

The result is a northeasterly wind that funnels through the valleys of the Alps, with winds usually strongest in the Geneva region.

This whipped up waves on Lake Geneva and created ice sculptures along the shoreline as water froze on the branches of trees and shrubbery.

The high winds have interrupted service of the CGN passenger boats for the past two days.

Temperatures fell to as low as minus 12 in the plain around Lake Geneva and ranged from minus 20 to 25 degrees in the higher areas of the Jura Mountains.

The lowest temperature in the country on Monday was recorded in a mountain region of Graubunden, where the mercury fell to minus 28.6 degrees, according to MeteoSwiss.

On Tuesday morning, temperatures fell even further, with the coldest spot identified as Glattalp, canton Schwyz, where it plummeted to a bone-snapping minus 38.9 degrees.

Zgraggen said the winter this year has been colder than normal, with chillier than average weather in January and February, followed by an icy start to March.

But he noted that winters were generally colder in the early part of the 20th century, with global warming having a moderating influence on the climate in recent years, even if it may not feel like it this week.

As to the longest recorded single period for the bise, Zgraggen said in February 1956 it blew for 20 days, with gusts up to 100 kilometres an hour and temperatures plunging to minus 20 degrees in Geneva.

The strongest bise ever recorded in Switzerland reached 110 kilometres an hour on April 25, 1972 when thousands of trees were knocked over in a storm, he said.

The bise can blow year round, but in the summer it usually brings warm air, Zgraggen said.

For those looking forward to a spring-like break, the weather pattern is forecast to change on Thursday with a 20 to 50 percent chance of sunshine, temperatures rising to four to seven degrees and no – or little –wind.