Island Park

Wind slab avalanches breaking two feet deep on recently drifted slopes are the primary hazard. Avoid wind-loaded terrain below cornices, near ridgelines, and where you encounter shooting cracks or a stiffening of snow surfaces. Play in wind-sheltered areas where conditions are much safer. A quick assessment of the upper three feet of the snowpack can further reduce your chances of triggering an avalanche.

In the Southern Gallatin and Southern Madison Ranges, and the Lionhead Area, avoiding large, persistent slab avalanches breaking 3-5 feet deep on buried weak layers should motivate today’s terrain selection. The chances of triggering a destructive avalanche are decreasing without new snow, but the consequences remain high. This weekend, Mark observed several natural avalanches that failed last week and provide insight into the danger (observation/ photos). Additionally, winds drifted snow into thick slabs below cornices and near ridgelines, where wind slab avalanches large enough to bury and critically injure riders or skiers could release. Wind-drifted snow will stabilize relatively quickly, but persistent slab avalanches are most likely on wind-loaded slopes, so these areas are worth avoiding. Select smaller, wind-sheltered slopes free from terrain traps or avoid pitches steeper than 30 degrees. The danger in the Southern Gallatin and Southern Madison Ranges, and the Lionhead Area is MODERATE.

Without the same concern for deeper avalanches in the Cooke City and Island Park areas, wind slab avalanches breaking two feet deep on recently wind-drifted slopes are the primary hazard. Natural and snowmobiler-triggered avalanches in the Goose Lake area, on Mineral Mountain, and Town Hill near Cooke City are good examples from the last few days. Avoid wind-loaded terrain below cornices and near ridgelines, and where shooting cracks or a stiffening of snow surfaces indicate instability. Play in wind-sheltered areas where conditions are much safer, and quickly assess the upper three feet of the snowpack for instability to reduce the chance of a surprise (Centennial Range observation, Alex’s Cooke City observations/ video). The danger in the Cooke City and Island Park Areas is MODERATE.

Strong winds are drifting the limited remaining soft snow, and wind slab avalanches breaking 6–12 inches deep are possible in the upper elevations of the Northern Gallatin and Northern Madison Ranges (Beehive observation 1, 2). Wind slabs are tricky; many are stabilizing, but a few could avalanche if they sit on weaker snow (observation from Hyalite). Watch and test for signs of instability near the top of the snowpack and consider the consequences of a slide in your selected terrain. Avalanches are unlikely in lower- and middle-elevation, wind-sheltered terrain. The danger is MODERATE at upper-elevation, and LOW at low- and middle-elevations in the Northern Gallatin and Northern Madison Ranges.

Conditions are generally stable in the Bridger Range, and avalanches are unlikely. Follow normal safety precautions and watch for isolated instability within drifts in steep, technical terrain, where a small avalanche could have more significant consequences. There is a possibility of strong, localized winds that could increase wind-loading rates. If these materialize, take a step back from steep, wind-loaded terrain. The danger is LOW at all elevations in the Bridger Range.

Recent Accidents

A snowmobiler was killed on Sunday in Wyoming after being buried two feet deep (preliminary information from the BTAC). On Friday (1/9), an avalanche in Washington caught four skiers and killed two (more information). Our thoughts are with families, friends, and responders.