DENVER -- Four human-caused avalanches in the past two days have avalanche forecasters reminding backcountry users to be cautious.

A skier was completely buried outside on Thursday outside of Vail -- one of three human-triggered slides that day. He was located and rescued by his skiing buddies, who heard his screams for help through the snow, without any injuries.

Ethan Greene, director of the Colorado Avalanche Information Center, said the skier jumped off a 25-foot cliff in an area called Mushroom Bowl. The depression is located next to Vail Ski Resort and a popular "side-country" destination.

"It is hard to say how they triggered the avalanche," Greene said. "You can say, though, that it was a skier-triggered avalanche."

Greene said the forecast for the area the skiers were at was considerable for the day. Considerable means that natural slides are possible and that human-triggered avalanches are probable. It is the second-highest level the center issues.

Also Thursday, a backcountry skier near Arapahoe Basin Ski Area near Loveland Pass triggered several small avalanches. Greene said the group escaped the bowl and a hairy situation by carefully picking their way out using safer terrain and making good route-finding decisions.

A skier was buried up to his neck outside of Silverton, in the southwest part of the state, on Wednesday. A group of skiers triggered an avalanche near Mayflower Gulch in the Ten Mile Range on Thursday but were not caught in it.

With a warm, sunny weekend forecasted, Greene cautions backcountry users not to be lulled into a sense of false security.

"We are far enough away from the loading cycle that we don't see natural avalanches," he said. "And that is the time when people often get in trouble or get killed. You don't have that flashing red light. You tend to let your guard down because the weather is so nice.

"There are still some lurking landmines you have to look for."

Greene the avalanche forecast for the Front Range and in Summit County is at considerable.