An avalanche warning has been issued for the San Juan Mountains by the Colorado Avalanche Information Center.
The warning starts at 4:30 p.m. Tuesday and runs through Thursday morning. Avalanche conditions are rated high, a Level 4 out of five on the danger scale, the CAIC reports.
Expect widespread avalanche activity large enough to bury or kill a person. Some avalanches will release spontaneously. Travel in backcountry avalanche terrain is not recommended.
“Heavy snowfall and strong winds are creating very dangerous avalanche conditions,” said CAIC Deputy Director Brian Lazar.
Areas impacted by the warning include areas surrounding Rico, Lizard Head Pass, La Plata Mountains, Hesperus, Telluride, Ophir, Coal Bank Pass, Molas Pass, Red Mountain Pass, Creede, Ouray, Silverton, Durango, Vallecito, Wolf Creek, Cumbres and La Manga Passes.
More information and specific maps are available by visiting the CAIC website.
Dangerous avalanche conditions will begin to develop Tuesday night and will reach High Level 4 danger by Wednesday morning. Ongoing heavy snowfall means larger avalanches will become more widespread as the day progresses Wednesday. A brief lull in snowfall happens Thursday before another impactful storm arrives over the weekend.
Lazar said the danger is a combination of a weak snowpack layer on the ground and sudden heavy accumulation of new snow.
“We have a pretty poor show infrastructure in place as it is and now we have a very potent winter storm barreling down on us,” Lazar said. “So this is going to drop lots of heavy dense snow in a short period of time, and the snowpack we have on the ground is just not going to be capable of supporting that rapid change. That's what is going to cause expected avalanches.”
The Level 4 out of five avalanche danger is widespread throughout the San Juans. While in some avalanche conditions it is possible to work out less dangerous aspects for safer passage, that is not the case in these conditions.
“That kind of nuance doesn’t help us when widespread natural avalanches large enough to bury you come into play,” the forecast states. “Travel in backcountry avalanche is simply not advised during the warning period.”
The forecast warned that large avalanches running long distances also can make it hard to know if an individual is far enough away from steep slopes overhead, and can make more comfortable areas below-treeline just as dangerous as higher elevations.
For example, traveling up a canyon such as Roaring Fork or Scotch Creek puts anyone at risk of avalanches releasing above them. In dangerous conditions, backcountry travelers are at risk of triggering avalanches some distance away from their position.
The National Weather Service has issued a Winter Storm Watch from Tuesday afternoon to Thursday morning for the mountains of Southwest Colorado and southeast Utah.
Heavy snow is possible mainly above 8,000 feet, with total accumulations of 10-18 inches with upward of 2 feet possible.
Travel could be very difficult, the weather service said. Patchy blowing snow could significantly reduce visibility, especially on ridge tops and mountain passes.
CAIC is working with CDOT to identify and mitigate avalanche dangers along roads and highways through the Southwest Colorado Mountains. CAIC will also conduct training for search and rescue groups.
An earlier avalanche watch issued by the CAIC was upgraded to an avalanche warning Tuesday. A warning means avalanche danger is currently happening, whereas a watch is avalanches are anticipated.
There has been one avalanche death this year in Colorado.
So far, there have been four reported accidents in the San Juan Mountains this winter, Lazar said.
Two avalanches caught skiers in the Red Mountain Pass area this season, and one person was injured. Another person was caught in an avalanche on Wolf Creek Pass.
An ice climber in South Mineral Creek near Silverton was caught in a natural avalanche that swept over him. The climber was roped in and survived unscathed.