Northern San Juan

Dangerous avalanche conditions develop Monday night into Tuesday. You can trigger an avalanche in the storm snow, and some avalanches may break several feet deep on buried weak layers.

A pair of recent accidents highlight the consequence of triggering a deep avalanche. On Friday, three backcountry skiers triggered and were caught in a large avalanche near Marble on an easterly-facing slope. Sadly one died. You can read the preliminary report here. Sunday afternoon another skier died in an accident in Maroon Bowl, on a northerly-facing slope near Aspen Highlands. You can read this preliminary report here.

An Avalanche Watch is in effect from Tuesday night through Thursday afternoon. Expect very dangerous avalanche conditions. Heavy snowfall and strong winds will produce natural avalanches, and human-triggered avalanches will be very likely. Avoid backcountry avalanche terrain during this time.

For Tuesday, you can trigger an avalanche which breaks in wind-drifted storm snow or which breaks on weak layers buried deeper in the snowpack. If you trigger an avalanche in a surface layer, it could break into these deeper weak layers and create a larger, more dangerous slide. The most suspect slopes face west through north to east, especially near and above-treeline northerly and easterly-facing slopes, where wind-drifted snow forms a thicker, more cohesive layer near the surface. Look for and avoid slopes with cornices above them, or with signs of wind-drifting such as smooth lens-shaped pillows or stiff, sculpted snow surfaces. You can trigger avalanches from the bottom of slopes, so give steeper terrain above you a wide margin. Slopes less than about thirty degrees without steep terrain above offer safer choices.