Northern San Juan

Avalanche

Chris Bilbrey · Apr 8, 2023 · Northern San Juan

Weather

Graybird day with moments of broken skies and sun. Mid-morning, skies became obscured and light snowfall lasted for maybe an hour. This did not lend to measurable accumulations. Winds were mostly light along ridgetops, with occasional moderate gusts.

Snowpack

The snow surface got a decent refreeze overnight. In general, boot penetration ranged 5 and 10 cm to start. This increased throughout the day below treeline as temperatures warmed. By mid-afternoon, boot penetration was deepest on southeast and south-facing slopes, and between 35 and 40 cm. The snow surface on those aspects consists of moist, unconsolidated round grains sitting above more supportive layers/ crust. The wetting front near treeline was about half the depth as below treeline. Despite weak surface snow, we could not initiate loose wet sluffs on steeper test slopes. We also encountered more rotten snow closer to trees than wide open areas. The snow surface showed less signs of softening/ weakening on similar sunny slopes above about 11,000 feet as below. The snowpack as a whole got more supportive as we moved up in elevation. Recent storm snow on northerly-facing slopes near and below treeline has consolidated into an inch or two above the old snow surface, and readily glopped to our skins. Above treeline on northerly-facing slopes, the latest round of snow has settled into about 5 to 8 inches of moderately dense wind-packed snow. We did not experience sluffing of the recent storm snow on slopes around 35 degrees. We found little evidence of stiff, wind slab formation on lee slopes in the alpine, but isolated areas harbor a harder, breakable surface close to ridgetops. The surface crust, on sunny slopes near treeline, softened enough to become breakable in the afternoon, but those same aspects above treeline remained firm today.

Avalanche

1 old crown from a slide that likely released around April 2, 2023.