Warming temperatures and increasing solar radiation throughout the day will make wet loose and cornice triggered avalanches possible today. Natural and human triggered wet loose avalanches will be most likely on Southern aspects earlier in the day and transition to Western and Northwestern aspects by the afternoon. Cornice failures will increase in likelihood throughout the day as well. Careful terrain choices are recommended on aspects with strong solar exposure and time spent under cornices should be minimized.
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Wet loose avalanches often start small but can grow large as they entrain snow. Wet loose avalanches are especially hazardous in steep exposed terrain and above terrain traps such as cliffs and gulleys. Signs of wet loose activity include wet saturated surface snow that feels unconsolidated, pinwheels and rollerballs on slopes, and snow shedding off rocks and trees due to solar heating.
Cornices are unpredictable and can fail without warning. Cornice failures can put a significant load on the slopes below them which can often trigger large avalanches. When traveling on ridgelines, cornices often fail much further back from their edges than expected as well. Cornices should be given a wide berth when traveling on corniced ridges and time spent under cornices should be minimized.
Over the past five days, we’ve seen an intermittent mix of rain and snow. Douglas received around a foot of new snow throughout the week, with freezing levels hovering near 1,500 feet. This has created variable skiing conditions, particularly at lower elevations. This warmer storm system arrived with moderate to strong ESE winds and contributed to significant cornice growth along ridgelines. With increasing solar input, these cornices may become reactive during the heat of the day.
Clear skies are now driving strong diurnal temperature swings, increasing the likelihood of crust formation overnight as the snow surface refreezes. Widespread tree shedding and rollerballs were observered throughout the day yesterday along with reports of natural wet loose avalanches in Cropley and on TSA ridgeline.
Mid elevations have remained above freezing for nearly 24 hours. With continued strong solar radiation today, expect additional wet loose activity and variable snow conditions, especially on solar aspects.
