Northern San Juan
AvalancheJason Bushey · Mar 26, 2023 · Northern San Juan
Weather
On Saturday, winds primarily loaded on easterly slopes in the morning with broken clouds. On Saturday despite the frigid temperatures observed surface warming BTL on E on the top 1" in the middle of the day due to solar radiation where I could make snowballs very easily. The temperature change from the North tree aspect to Easterly was roughly 15 degree warmer due to the sun, and my fingers appreciated the change. Sunday was cold and overcast all day with periods of light snowfall never accounting to much accumulation and unknown loading patterns near and above treeline. A 3" deep styrofoam style crust was found on small south aspects near 9K, likely from brief warming on Saturday.
Snowpack
A few isolated (<15') isolated collapses on Saturday where one party member would hear and another close would not. No cracking. No cracking or collapsing on Sunday. The biggest surprise to me was how many slopes were still in tact from the high danger event, especially slopes that had previously avalanched which I would have expected to been pushed past their tipping point again. This includes the northerly faces on Sultan which avalanched a couple weeks ago. Near and above treeline slopes were plump and looked full of energy throughout the weekend. Many W facing slopes near ridgelines showed rock from violent winds in the last storm. Hand pits and shovel sheers on north btl (in timber just down from ridges with slight wind loading) on Saturday showed broken interfaces 30 and 70cm down. The 70cm interface interestingly showed a small melt freeze on one cut of the column and not on the other side on both shovel sheers in locations 100' apart. Trail breaking BTL was typically 40cm on Saturday and decreased to 20-30cm on Sunday.
Avalanche
Saw 2 avalanches from the high danger event. Coding to that timeframe all estimated.