Southern San Juan

Avalanche

Chris Bilbrey · Apr 8, 2022 · Southern San Juan

Weather

Warm and sunny with light westerly wind. We observed air temperature around 50 degree Fahrenheit around 10,000 feet at 4 pm in a shaded location.

Snowpack

The snow surface and the upper snowpack has benefited from cooler temperatures in recent days. We found generally supportive surfaces on all aspects in the morning hours. As the day progressed surfaces quickly softened from warm temperatures, light wind, and abundant sunshine. Later in the day, the top 3 to 4 inches of snow was wet on east to south through west slopes above treeline. Depth of wet snow increased to around 6 inches on the same slopes near treeline. Below the wet surface snow, a firm re-frozen layer was supportive to boot penetration. This refrozen layer was less robust below 11,000 feet with trap door conditions on most aspects as we descended lower in the terrain. Even northerly slopes below treeline were not void of today's warmup. The top 4 to 5 inches of snow got wet and minor wet snow sluffing noted on a northeast aspect where slope angles approached 35 degrees. A snowpit on an east-facing slope at treeline produced concerning results in wet, 4F faceted snow below a pencil hard slab. These soft, wet grains were around 70 cm's below the surface and failed with easy-moderate force in Compression and Extended Column Test. Upon weak layer failure, a crack propagated across the entire column and the cohesive slab slid off the column ending up at our feet rather quickly. These results raise concern of a potential uptick in Wet Slab avalanche activity if we return to a prolonged string of non-freezing nighttime temperatures. While frozen percolation columns exist below this weak layer interface, the reactivity suggest that as the overlying slab softens, it could become susceptible to failing from the added weight of a rider. This may be more of a rider-triggering threat than a natural wet avalanche threat.

Avalanche

No fresh natural wet snow slides visible during our travels. Only small, rollerball action from steeper slopes near rocky outcrops on east and southerly slopes.