A participant jumps on snowmobile in front of the Alexander Column on the Palace Square during a festival of youth street culture in St. Petersburg, June 28, 2014. REUTERS/Alexander Demianchuk (RUSSIA - Tags: SOCIETY SPORT) 

Snowmobilers circle a 50-foot snowman named "Granddaddy" in Gilman, Minnesota, March 6, 2014. The snowman began to take shape earlier this winter when farmer Greg Novak needed to move mounting snow piles away from his greenhouses. REUTERS/Eric Miller (UNITED STATES - Tags: ENVIRONMENT SOCIETY) 

Spectators (bottom) watch snowmobiles riders descending down from the slope in the town of Zheleznogorsk, some 50km (31 miles) northeast of Russia's Siberian city of Krasnoyarsk, March 1, 2014. Local residents organized an annual winter torch festival to promote sports and a healthy way of life, according to organizers. Picture taken with long exposure. Picture taken March 1, 2014. REUTERS/Ilya Naymushin (RUSSIA - Tags: SOCIETY) 

Men's Pro Open riders compete in the Canadian Snowcross Racing Association's (CSRA) Kawartha Cup in Lindsay, Ontario February 8, 2014. The snowmobile event is part of CSRA's professional circuit of racing in Ontario and Quebec. The Kawartha Lakes event continues tomorrow. REUTERS/Fred Thornhill (CANADA - Tags: SPORT MOTORSPORT) 

Men's Pro Open riders compete in the Canadian Snowcross Racing Association's (CSRA) Kawartha Cup in Lindsay, Ontario February 8, 2014. The snowmobile event is part of CSRA's professional circuit of racing in Ontario and Quebec. The Kawartha Lakes event continues tomorrow. REUTERS/Fred Thornhill (CANADA - Tags: SPORT MOTORSPORT TPX IMAGES OF THE DAY) 

Professional snowmobile rider and stunt performer Jimmy Blaze from Alaska appears to be flying through clouds as he comes off a jump at the Canadian Snowcross Racing Association's (CSRA) Kawartha Cup in Lindsay, Ontario February 8, 2014. The snowmobile event is part of CSRA's professional circuit of racing in Ontario and Quebec. The Kawartha Lakes event continues tomorrow. REUTERS/Fred Thornhill (CANADA - Tags: SPORT MOTORSPORT) 

Professional snowmobile rider and stunt performer Jimmy Blaze from Alaska appears to be flying through clouds as he comes off a jump at the Canadian Snowcross Racing Association's (CSRA) Kawartha Cup in Lindsay, Ontario February 8, 2014. The snowmobile event is part of CSRA's professional circuit of racing in Ontario and Quebec. The Kawartha Lakes event continues tomorrow. REUTERS/Fred Thornhill (CANADA - Tags: SPORT MOTORSPORT) 

Men's Pro Open riders compete in the Canadian Snowcross Racing Association's (CSRA) Kawartha Cup in Lindsay, Ontario February 8, 2014. The snowmobile event is part of CSRA's professional circuit of racing in Ontario and Quebec. The Kawartha Lakes event continues tomorrow. REUTERS/Fred Thornhill (CANADA - Tags: SPORT MOTORSPORT) 

Men's Pro Open riders compete in the Canadian Snowcross Racing Association's (CSRA) Kawartha Cup in Lindsay, Ontario February 8, 2014. The snowmobile event is part of CSRA's professional circuit of racing in Ontario and Quebec. The Kawartha Lakes event continues tomorrow. REUTERS/Fred Thornhill (CANADA - Tags: SPORT MOTORSPORT) 

A snow cat traverses through a tunnel under the Men's Olympic Downhill course 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/Mike Blake (RUSSIA - Tags: SPORT OLYMPICS SKIING TPX IMAGES OF THE DAY) 

A course worker drives a snowmobile as the second training session of the Women's World Cup Downhill skiing race was cancelled due to heavy snowfall in Cortina D'Ampezzo January 17, 2014. REUTERS/Max Rossi (ITALY - Tags: SPORT SKIING ENVIRONMENT) 

People ride snowmobiles along a snow-covered bank of the Yenisei River in front of the Krasnoyarsk hydroelectric power station outside Russia's Siberian city of Krasnoyarsk, January 12, 2014. REUTERS/Ilya Naymushin (RUSSIA - Tags: ENVIRONMENT SOCIETY TRANSPORT) 

A girl drives a snowmobile towing another girl in a sled after a fresh snowfall in Newtown, Connecticut December 15, 2013. Locals have been striving to return to normal even as yesterday marked the one year anniversary of the shooting rampage at Sandy Hook Elementary School, where 20 children and six adults were killed by gunman Adam Lanza. REUTERS/Carlo Allegri (UNITED STATES - Tags: CRIME LAW ANNIVERSARY) 

Executives from Fox Factory Holding Corp. take photos on a snowmobile following ringing of the opening bell at the Nasdaq Market to celebrate the company's IPO in New York, August 8, 2013. Fox Factory Holding Corp. opened to the public at $15 per share. FOX builds high-performance suspension products that are used mostly on mountain bikes, snowmobiles, off-road trucks and other adventure vehicles. REUTERS/Brendan McDermid (UNITED STATES - Tags: BUSINESS SOCIETY) 

Snowmobile racer Levi LaVallee jumps his snowmobile as executives from Fox Factory Holding Corp. ring the opening bell for the Nasdaq Market to celebrate the company's IPO in New York, August 8, 2013. Fox Factory Holding Corp. opened to the public at $15 per share. FOX builds high-performance suspension products that are used mostly on mountain bikes, snowmobiles, off-road trucks and other adventure vehicles. REUTERS/Brendan McDermid (UNITED STATES - Tags: BUSINESS SOCIETY SPORT) 

Snowmobile racer Levi LaVallee jumps his snowmobile as executives from Fox Factory Holding Corp. ring the opening bell for the Nasdaq Market to celebrate the company's IPO in New York, August 8, 2013. Fox Factory Holding Corp. opened to the public at $15 per share. FOX builds high-performance suspension products that are used mostly on mountain bikes, snowmobiles, off-road trucks and other adventure vehicles. REUTERS/Brendan McDermid (UNITED STATES - Tags: BUSINESS SOCIETY SPORT) 

A stunt rider performs with two spectators onboard during the Adrenaline FMX Rush moto freestyle show in Russia's Siberian city of Krasnoyarsk, July 2, 2013. Russian and foreign professional riders showed their skills in stunt riding and freestyle jumping on sport bikes, a quad bike and a snowmobile. REUTERS/Ilya Naymushin (RUSSIA - Tags: SOCIETY SPORT) 

Riders perform during the Adrenaline FMX Rush moto freestyle show in Russia's Siberian city of Krasnoyarsk, July 2, 2013. Russian and foreign professional riders showed their skills in stunt riding and freestyle jumping on sport bikes, a quad bike and a snowmobile. REUTERS/Ilya Naymushin (RUSSIA - Tags: SOCIETY SPORT) 

Colton Moore of the U.S. rides a snowmobile as he performs during the Adrenaline FMX Rush moto freestyle show in Russia's Siberian city of Krasnoyarsk, July 2, 2013. Russian and foreign professional riders showed their skills in stunt riding and freestyle jumping on sport bikes, a quad bike and a snowmobile. REUTERS/Ilya Naymushin (RUSSIA - Tags: SOCIETY SPORT TPX IMAGES OF THE DAY) 

Karl Reisinger (L) and David Schneider, technicians of the University of Applied Sciences in Graz (FH Joanneum Graz) carry out last checks on a prototype electric snow mobile in a workshop of the University in Graz February 21, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one. Picture taken February 21. REUTERS/Herwig Prammer (AUSTRIA - Tags: TRANSPORT SCIENCE TECHNOLOGY) 

David Schneider, a technician of the University of Applied Sciences Graz (FH Joanneum Graz), tests a prototype electric snow mobile on a field near Graz February 22, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports, but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one. Picture taken February 22. REUTERS/Herwig Prammer (AUSTRIA - Tags: SCIENCE TECHNOLOGY) 

A laptop lies on cables as last checks on prototype electric snowmobile are done in a workshop of the University of Applied Sciences (FH Joanneum Graz) in Graz February 21, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one. Picture taken February 21. REUTERS/Herwig Prammer (AUSTRIA - Tags: SCIENCE TECHNOLOGY TRANSPORT) 

David Schneider, scientific assistant at the University of Applied Sciences Graz (FH Joanneum Graz), tests 'Snowbird' a prototype electric snowmobile on a slope at Packsattel mountain, some 50 kilonetres (some 30 miles) west of Graz, March 11, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one. Picture taken March 11. REUTERS/Herwig Prammer (AUSTRIA - Tags: SCIENCE TECHNOLOGY TRANSPORT) 

David Schneider, scientific assistant at the University of Applied Sciences Graz (FH Joanneum Graz), tests 'Snowbird' a prototype electric snowmobile on a slope at Packsattel mountain, some 50 kilonetres (some 30 miles) west of Graz, March 11, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one.Picture taken March 11. REUTERS/Herwig Prammer (AUSTRIA - Tags: SCIENCE TECHNOLOGY TRANSPORT) 

David Schneider and other technicians of the University of Applied Sciences Graz (FH Joanneum Graz) make checks before testing a prototype electric snowmobile on a field near Graz February 22, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one. Picture taken February 22. REUTERS/Herwig Prammer (AUSTRIA - Tags: TRANSPORT SCIENCE TECHNOLOGY) 

David Schneider, scientific assistant at the University of Applied Sciences Graz (FH Joanneum Graz), tests 'Snowbird' a prototype electric snowmobile on a slope at Packsattel mountain, some 50 kilonetres (some 30 miles) west of Graz, March 11, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one. Picture taken March 11. REUTERS/Herwig Prammer (AUSTRIA - Tags: SCIENCE TECHNOLOGY TRANSPORT) 

Technicians of the University of Applied Sciences Graz (FH Joanneum Graz), test a prototype electric snow mobile on a field near Graz February 22, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports, but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one. Picture taken February 22. REUTERS/Herwig Prammer (AUSTRIA - Tags: SCIENCE TECHNOLOGY) 

David Schneider, a technician of the University of Applied Sciences Graz (FH Joanneum Graz), tests a prototype electric snow mobile on a field near Graz February 22, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports, but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one. Picture taken February 22. REUTERS/Herwig Prammer (AUSTRIA - Tags: SCIENCE TECHNOLOGY) 

Karl Reisinger (R) and David Schneider, technicians of the University of Applied Sciences in Graz (FH Joanneum Graz) carry out last checks on a prototype electric snow mobile in a workshop of the University in Graz February 21, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one. Picture taken February 21. REUTERS/Herwig Prammer (AUSTRIA - Tags: TRANSPORT SCIENCE TECHNOLOGY) 

Technicians of the University of Applied Sciences in Graz (FH Joanneum Graz) carry out last checks on a prototype electric snow mobile in a workshop of the University in Graz February 21, 2013. Snowbird - Austria's first all-electric snowmobile, not only makes a contribution to resource-efficient and sustainable mountain rescue in the field of winter sports but is a quiet, zero-emission snowmobile which offers a high degree of safety due to its operation at lower speeds. The prototype, which was developed by Energie Steiermark and FH Joanneum in collaboration with the Styrian regional government and cable car company Planai-Hochwurzen-Bahnen, still costs some 10,000 euros (13,000 USD) more than a conventional one. Picture taken February 21. REUTERS/Herwig Prammer (AUSTRIA - Tags: TRANSPORT SCIENCE TECHNOLOGY) 

A snowmobile and cars drive along the frozen Yenisei River in the taiga area some 52 km (32 miles) south of Russia's Siberian city of Krasnoyarsk, February 4, 2013. REUTERS/Ilya Naymushin (RUSSIA - Tags: ENVIRONMENT TRANSPORT) 

Rescue workers stand on a snow groomer as they transport the bodies of two Russian tourists who died on the Alpe Cermis in Val di Fiemme, northern Italy January 5, 2013. Six Russian tourists were killed and two seriously injured on Friday when a snowmobile tipped over and plunged down a steep ski slope in the Italian Alps, rescue workers said. REUTERS/Alessandro Garofalo (ITALY - Tags: TRAVEL DISASTER TPX IMAGES OF THE DAY) 

Rescue workers wait during the rescue operations to recover the bodies of six Russian tourists who died on the Alpe Cermis in Val di Fiemme, northern Italy January 5, 2013. Six Russian tourists were killed and two seriously injured on Friday when a snowmobile tipped over and plunged down a steep ski slope in the Italian Alps, rescue workers said. REUTERS/Alessandro Garofalo (ITALY - Tags: TRAVEL DISASTER) 

Rescue workers wait during the rescue operations to recover the bodies of six Russian tourists who died on the Alpe Cermis in Val di Fiemme, northern Italy January 5, 2013. Six Russian tourists were killed and two seriously injured on Friday when a snowmobile tipped over and plunged down a steep ski slope in the Italian Alps, rescue workers said. REUTERS/Alessandro Garofalo (ITALY - Tags: TRAVEL DISASTER) 

A medical staff member wheels the body of a Russian tourist who died on the Alpe Cermis in Val di Fiemme, northern Italy January 5, 2013. Six Russian tourists were killed and two seriously injured on Friday when a snowmobile tipped over and plunged down a steep ski slope in the Italian Alps, rescue workers said. REUTERS/Alessandro Garofalo (ITALY - Tags: TRAVEL DISASTER) 

Rescue workers and authorities wait during the rescue operations to recover the bodies of six Russian tourists who died on the Alpe Cermis in Val di Fiemme, northern Italy January 5, 2013. Six Russian tourists were killed and two seriously injured on Friday when a snowmobile tipped over and plunged down a steep ski slope in the Italian Alps, rescue workers said. REUTERS/Alessandro Garofalo (ITALY - Tags: TRAVEL DISASTER) 

A rescue worker stands on a snow groomer as he transports the body of a Russian tourist who died on the Alpe Cermis in Val di Fiemme, northern Italy January 5, 2013. Six Russian tourists were killed and two seriously injured on Friday when a snowmobile tipped over and plunged down a steep ski slope in the Italian Alps, rescue workers said. REUTERS/Alessandro Garofalo (ITALY - Tags: TRAVEL DISASTER) 

Red Cross members look on as they wait during rescue operations to recover the bodies of six Russian tourists who died on the Alpe Cermis in Val di Fiemme, northern Italy January 5, 2013. Six Russian tourists were killed and two seriously injured on Friday when a snowmobile tipped over and plunged down a steep ski slope in the Italian Alps, rescue workers said. REUTERS/Alessandro Garofalo (ITALY - Tags: TRAVEL DISASTER) 

Rescuers stand on a snow groomer as they carry the bodies of two Russian tourists who died on the Alpe Cermis in Val di Fiemme, northern Italy January 5, 2013. Six Russian tourists were killed and two seriously injured on Friday when a snowmobile tipped over and plunged down a steep ski slope in the Italian Alps, rescue workers said. REUTERS/Alessandro Garofalo (ITALY - Tags: DISASTER TRAVEL) 

A snowmobiler flies through the air as part of the entertainment during the Monster Energy Snowmobile Freestyle tour at the World Cup Ski Cross race in Nakiska, Alberta, December 8, 2012. REUTERS/Todd Korol (CANADA - Tags: SPORT SOCIETY) 

A snowmobiler flies through the air as part of the entertainment during the Monster Energy Snowmobile Freestyle tour at the World Cup Ski Cross race in Nakiska, Alberta, December 8, 2012. REUTERS/Todd Korol (CANADA - Tags: SPORT SOCIETY) 

Canada's Prime Minister Stephen Harper (C) rides a snowmobile with members of the Canadian Rangers on Frobisher Bay in Iqaluit, Nunavut February 23, 2012. REUTERS/Chris Wattie (CANADA - Tags: POLITICS) 

A snowmobiler rides past sled dogs on Frobisher Bay in Iqaluit, Nunavut February 23, 2012. REUTERS/Chris Wattie (CANADA - Tags: SOCIETY ANIMALS) 

Canada's Prime Minister Stephen Harper (L) rides a snowmobile with a member of the Canadian Rangers on Frobisher Bay in Iqaluit, Nunavut February 23, 2012. REUTERS/Chris Wattie (CANADA - Tags: POLITICS SOCIETY) 

Canada's Prime Minister Stephen Harper rides a snowmobile with members of the Canadian Rangers on Frobisher Bay in Iqaluit, Nunavut February 23, 2012. REUTERS/Chris Wattie (CANADA - Tags: POLITICS) 

Canada's Prime Minister Stephen Harper (R) rides a snowmobile with members of the Canadian Rangers on Frobisher Bay in Iqaluit, Nunavut February 23, 2012. REUTERS/Chris Wattie (CANADA - Tags: POLITICS) 

Canada's Prime Minister Stephen Harper rides a snowmobile with members of the Canadian Rangers on Frobisher Bay in Iqaluit, Nunavut February 23, 2012. REUTERS/Chris Wattie (CANADA - Tags: POLITICS TPX IMAGES OF THE DAY) 

A man rides his snowmobile, about 40 km (25 miles) southeast of the town of Naryan-Mar, in northern Russia February 19, 2012. The Nenets are the indigenous tribe people of Russia's Far North, who live in poorly populated and developed Tundra region, near the coast of the Arctic Ocean. Picture taken February 19, 2012. REUTERS/Anton Golubev (RUSSIA - Tags: SOCIETY) 

People rest near their snowmobiles, about 40 km (25 miles) southeast of the town of Naryan-Mar, in northern Russia February 19, 2012. The Nenets are the indigenous tribe people of Russia's Far North, who live in poorly populated and developed Tundra region, near the coast of the Arctic Ocean. Picture taken February 19, 2012. REUTERS/Anton Golubev (RUSSIA - Tags: SOCIETY) 

Men drive a snowmobile, about 70 km (43 miles) southeast of the town of Naryan-Mar, in northern Russia, February 19, 2012. The Nenets are the indigenous tribe people of Russia's Far North, who live in poorly populated and developed Tundra region, near the coast of the Arctic Ocean. Picture taken February 19, 2012. REUTERS/Anton Golubev (RUSSIA - Tags: SOCIETY) 

Stefano Gross (R) of Italy walks to the podium after arriving on a snowmobile for the award ceremony at the men's alpine skiing World Cup slalom race at the Bulgarian ski resort of Bansko, some 150 km (93 miles) south of Sofia February 19, 2012. REUTERS/Stoyan Nenov (BULGARIA - Tags: SPORT SKIING) 

A man drives a snowmobile on the frozen Pechora river in the town of Naryan-Mar in the Nenets Autonomous region in Russia's far north, February 18, 2012. REUTERS/Anton Golubev (RUSSIA - Tags: SOCIETY ENVIRONMENT) 

A participant competes in the Winter Race 2012 annual amateurs snowmobile competition at the Bobrovy Log ski resort outside Russia's Siberian city of Krasnoyarsk February 18, 2012. REUTERS/Ilya Naymushin (RUSSIA - Tags: SPORT SOCIETY) 

Participants compete in the Winter Race 2012 annual amateurs snowmobile competition at the Bobrovy Log ski resort outside Russia's Siberian city of Krasnoyarsk February 18, 2012. REUTERS/Ilya Naymushin (RUSSIA - Tags: SPORT SOCIETY) 

A participant competes in the Winter Race 2012 annual amateurs snowmobile competition at the Bobrovy Log ski resort outside Russia's Siberian city of Krasnoyarsk February 18, 2012. REUTERS/Ilya Naymushin (RUSSIA - Tags: SPORT SOCIETY) 

Participants compete in the Winter Race 2012 annual amateurs snowmobile competition at the Bobrovy Log ski resort outside Russia's Siberian city of Krasnoyarsk February 18, 2012. REUTERS/Ilya Naymushin (RUSSIA - Tags: SPORT SOCIETY) 

A participant competes in the Winter Race 2012 annual amateurs snowmobile competition at the Bobrovy Log ski resort outside Russia's Siberian city of Krasnoyarsk February 18, 2012. REUTERS/Ilya Naymushin (RUSSIA - Tags: SPORT SOCIETY) 

A tourist rides on a snowmobile during winter at Wierch Rusinski in Bukowina Tatrzanska near Zakopane, southern Poland, February 11, 2012, as the Tatra Mountains are seen in the background. REUTERS/Kacper Pempel (POLAND - Tags: TRAVEL ENVIRONMENT) 

Men ride a snowmobile through the snow in Denver, Colorado, February 3, 2012. A winter storm walloped eastern Colorado with its first heavy snow of the new year on Friday, closing schools, forcing flight cancellations at Denver International Airport and creating blizzard conditions on the High Plains. REUTERS/Nathan W. Armes (UNITED STATES - Tags: ENVIRONMENT) 

A man rides a snowmobile through the snow in Denver, Colorado, February 3, 2012. A winter storm walloped eastern Colorado with its first heavy snow of the new year on Friday, closing schools, forcing flight cancellations at Denver International Airport and creating blizzard conditions on the High Plains. REUTERS/Nathan W. Armes (UNITED STATES - Tags: ENVIRONMENT)