What was an already difficult ridge climb for accomplished ice climber Caroline George had suddenly turned scary and treacherous.
The year was 2004, and she was in the midst of a three-day climb nearing the summit of the Weisshorn, a 13,123-foot (4000-meter) peak in the Swiss Alps.
George, who has scaled some of the most challenging peaks around the work and competed for three years in the Ice Climbing World Cup, said the weather was forecast to be perfect, but as she and her group continued their ascent, they could see storms coming their way.
"I was calling the Geneva Airport weather forecasting service and they kept telling me that nothing was coming our way. But simultaneously, we were getting thunder, lightning and snow," George said in an email.
Fortunately, George and the members of her group escaped unscathed, but the severe weather made the descent problematic, because it was very cloudy and the rocks were wet, making it slippery and dangerous.
"It was an intense experience," George said.
George's encounter is just one example of how extreme, sudden changes in weather can endanger even the most experienced and prepared outdoors-men.
Along with her husband, Adam, also an experienced climber, she owns "Into the Mountains," a guide service focused on climbing trips in the European Alps and in North America.
George, who also leads skiing trips, said wind chill factor is one of the most frequent dangers she encounters when in the mountains. She added that wind can impact the snow pack, creating wind slabs that are a red flag for avalanches.
"Either way, the wind is a very key factor in the mountains that must always be monitored, not only on the day you are going out, but it is also important to know the history of the wind events of the previous days," she said.
Whenever she's preparing for a trip, George said she makes sure to bring a GPS, map, compass and altimeter. In case of stormy weather, she makes sure to plan her itinerary well ahead of time and also packs extra layers, as well as a tarp, hot tea and plenty of food.
"Weather Changes Fast in the Mountains"
Avalanches are a common threat for back-country expeditions around the world, and many natural triggers of avalanches are weather related.
Jaime Musnicki, executive director of the American Avalanche Association, said weather is the architect of the snowpack.
Musnicki said weather factors, such as temperature and amount of snowfall, influence whether weak layers form in the snowpack. Additionally, if a snowpack's structure is weak, temperature and wind speed and direction as well as amount and type of precipitation are components that can initiate an avalanche.
Artificial triggers of an avalanche include human activity, such as hiking, skiing or snowmobiling near an avalanche slope. Avalanches can occur very quickly and can even reach speeds up to 60 mph, according to Musnicki.
For those who are planning a back-country skiing or hiking expedition, Musnicki recommended becoming educated about avalanches, including learning how to recognize avalanche terrain. In addition, she suggested acquiring the proper equipment, such as avalanche beacons, shovel and a probe, as well as checking the avalanche advisory from the local avalanche forecasting center.
In early October, two experienced extreme skiers died in Chile after being swept away by an avalanche.
"Weather changes fast in the mountains and you should always be prepared to face what might be coming your way," George said.
"Someone might get hurt and you might be forced to spend the night, you might have to go a way you hadn't expected to go and be forced to cross an avalanche slope you hadn't expected to cross," she added.
Just last week, deadly blizzards and avalanches struck in a popular trekking region in the Himalayan Mountains in Nepal, leaving at least 39 dead, according to the BBC.
According to the Associated Press, survivors of the blizzards said they were caught off guard when the weather changed quickly.
"We could hardly see anyone, even within a couple of feet. The wind was blowing snow, and visibility was almost zero," Gombu Sherpa, a guide who was leading a group of Germans, told the AP.
"There is Intrinsic Risk to Traveling Outdoors"
The Pacific Crest Trail (PCT) stretches more than 2,600 miles from Mexico to Canada, winding its way through California, Oregon and Washington. Due to its vast expanse, encountering bad weather on the trail is almost a certainty for those looking to travel the trail in its entirety.
Jack Haskel, a trail information specialist for the Pacific Crest Trail Association, has traversed every inch of the PCT, and said he thru-hiked the entire trail in five months and four days.
Haskel, 30, has been hiking and backpacking for nearly his entire life. Haskel is quite familiar with having to adapt to the elements because in addition to his journeys traveling the trail, he has also worked as an outdoor guide, teaching backpacking, winter camping and cross country skiing among other activities. Due to his extensive outdoor work, Haskel said there have been several years when he has lived outside for more than 300 days a year.
Cold and wet conditions can occur at any time, Haskel said. In one case, he said he was snowed on in California during the middle of summer.
"Generally, these are small summertime snow events, not terribly significant and they come along with significant changes in the weather pattern, so I encourage everybody to know a little bit about the different types of clouds and signs that weather is coming through," Haskel said.
During this time of year, Haskel said that cold, fall storms can occur at any time, so it's critically important that people check the weather forecast before embarking on their trip.
"Hikers and backpackers should definitely be aware that hiking in the Pacific Northwest can be cold and very wet, including significant snowstorms happening as early as mid-September, and smaller storms that can be a threat to life or safety earlier in the year."
In October 2013, one PCT long-distance hiker was rescued after being stranded for a week following a heavy snowstorm that dumped several feet of snow on the trail.
The storm, which occurred in late September, caused a lot of disruptions and a lot of people were unprepared, according to Haskel.
While thousands will travel the PCT every year, the majority of those who visit the trail are short-term hikers looking for a day, weekend or week-long trip. For the long-distance hikers that are attempting to thru-hike the entire PCT in one season, they need to go quite quickly, in order to time their trip for the snow-free season.
This time of year is actually pretty late to be on the trail, according to Haskel; however, those who are hiking southbound through Southern California likely have an extra month to travel versus those heading northbound into Canada.
The PCTA does not keep tabs on those who embark on the trail, so hikers must prepare to be self-reliant.
Haskel explained that whenever he embarks on a trip, he always gives an itinerary to family members and a trusted friend, typically one who is an experienced hiker and is familiar with the area he is going to be traveling.
"It's important that people realize that there is intrinsic risk to traveling outdoors and that they be prepared, do their research and travel with a partner," he said.