A snow making machine is seen in the Verbier ski resort in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse 

A snow making machine is seen in the Verbier ski resort in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse 

A snow making machine is seen in the Verbier ski resort in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse 

A snow making machine is seen in the Verbier ski resort in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse 

Snowmaker Jose Martinez of the Verbier ski resort checks the artificial snow making machine in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse 

An artificial snow making machine is seen in the Verbier ski resort in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse

An artificial snow making machine is seen in the Verbier ski resort in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse

Snowmaker Jose Martinez of the Verbier ski resort checks the artificial snow making machine in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse 

An artificial snow making machine is seen in the Verbier ski resort in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse

An artificial snow making machine is seen in the Verbier ski resort in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse

An artificial snow making machine is seen in the Verbier ski resort in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse

An artificial snow making machine is seen in the Verbier ski resort in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse

Snowmakers of the Verbier ski resort check the artificial snow making machine in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse TPX IMAGES OF THE DAY 

Snowmaker Jose Martinez of the Verbier ski resort checks the artificial snow making machine in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse 

Snowmaker Jose Martinez of the Verbier ski resort checks the artificial snow making machine in Verbier, Switzerland, November 28, 2016. REUTERS/Denis Balibouse 

A girl stands on a lift at the skiing area of the western city Winterberg, Germany December 29, 2015. REUTERS/Ina Fassbender 

Visitors ski on a piste made with artificial snow by a snow cannon during warm weather in the western German ski resort of Winterberg some 80km southeast of Dortmund, Germany December 22, 2015. REUTERS/Wolfgang Rattay TPX IMAGES OF THE DAY 

A woman walks her dog along a small hill made of artificial snow by a snow cannon during warm weather in the western German ski resort of Winterberg some 80km southeast of Dortmund, Germany December 22, 2015. REUTERS/Wolfgang Rattay 

People play on a small hill made of artificial snow by a snow cannon during warm weather in the western German ski resort of Winterberg some 80km southeast of Dortmund, Germany December 22, 2015. REUTERS/Wolfgang Rattay 

Visitors ski on a piste made with artificial snow by a snow cannon during warm weather in the western German ski resort of Winterberg some 80km southeast of Dortmund, Germany December 22, 2015. REUTERS/Wolfgang Rattay 

People play on a small hill made of artificial snow by a snow cannon during warm weather in the western German ski resort of Winterberg some 80km southeast of Dortmund, Germany December 22, 2015. REUTERS/Wolfgang Rattay 

Visitors ski on a piste made with artificial snow by a snow cannon during warm weather in the western German ski resort of Winterberg some 80km southeast of Dortmund, Germany December 22, 2015. REUTERS/Wolfgang Rattay 

A snow making machine stands on a snowless slope on Gschwandtkopf mountain in the western Austrian village of Seefeld November 28, 2014. REUTERS/Dominic Ebenbichler (AUSTRIA - Tags: ENVIRONMENT)

A course worker adjusts her hat beside a working snow cannon during preparations at the Rosa Khutor alpine resort near Sochi, January 31, 2014. Sochi will host the 2014 Winter Olympic Games from February 7 to 23. REUTERS/Kai Pfaffenbach (RUSSIA - Tags: SPORT OLYMPICS) 

A snow cannon produces artificial snow in the finish area of the 'Kandahar' racing course for the Alpine Skiing World Championships in Garmisch-Partenkirchen January 5, 2011. The organizers of the GAP 2011 skiing championships that are scheduled for February 7 - 20, are struggling with a local farmer over the usage of his meadows for the finish area of the speed events. The mayor of the 26,000 inhabitants strong Bavarian town is also facing a battle with some 59 farmers that have launched an attempt to prevent their land from being used for Germany's bid for the 2018 Winter Olympic Games in Munich. REUTERS/Wolfgang Rattay (GERMANY - Tags: POLITICS SPORT SKIING) 

A worker uses a snowblower to remove snow from a street at the Swiss mountain resort of Flumserberg some 90 kilometres east of Zurich November 16, 2007. After heavy snowfalls during the last week Flumserberg opened this years winter sport season. REUTERS/Arnd Wiegmann (SWITZERLAND) 

Markus Zeller, employee of Flumser Bergbahnen controls a snow cannon on a ski-piste at the Swiss mountain resort of Flumserberg some 90 kilometres (56 miles) east of Zurich November 16, 2007. After heavy snowfalls during the last week Flumserberg opened this year for the winter sport season on Friday. REUTERS/Arnd Wiegmann (SWITZERLAND)