Arctic Valley backcountry:
Obvious signs of instability (red flags):
- Very small human triggered wind slabs
- Recent wet loose avalanches
- Active wind loading in some areas
- Somewhat recent D2-D2.5 large persistent slabs (at least two) in 3 Bowls (South Fork)
- Partly cloudy skies over the NW Chugach becoming more cloudy and obscured to the SE
- Alpine temps in the upper 20s to lower 30s
- Light to moderate SE wind
- Variable wind, sun, and warmth affected snow. The series of recent warm storms has greatly improved the upper elevation base with heavy, moist snow. However, many areas are “punchy” and “grabby” with breakable wind and melt-freeze crusts. A proper melt-freeze cycle has not yet commenced as temps have neither been hot or cold enough.
There has been a lot of natural wet loose avalanche activity and roller balls from steep terrain on more westerly aspects in the Gordon Lyon – Nike north bowls. We avoided bigger and more open slopes, and managed terrain on our descents by using “walled-in” and raised terrain features with ski cuts. We were able to suss out some very small wind slabs on obviously loaded terrain features, and experienced sluffing on steep terrain with dry snow.
A pit near the top of Gordon Lyon revealed the expected concerns: near surface instability due to rapid faceting below recent melt-freeze crust, mid snowpack persistent slab from snowfall and windloading the past couple weeks above heavily faceted snow (from the month long dry spell) on hard wind slab, and deep persistent slab from advanced basal facets and depth hoar below thick hard slab). This snowpit was somewhat unrepresentative due to the deeper snowpack close to the leeward ridge (i.e. expect persistent instabilities to be more reactive where the snowpack is thinner).
~4050′, 250* W aspect, 38* slope, ~135cm HS, ECTN1 down ~10cm (4F recently wind loaded snow on 1F+ melt-freeze crust with 4F facets below), ECTN13 down ~ 40cm (1F snow from the past couple weeks on 4F heavily faceted snow from month long dry spell above P windpacked hard slab), ECTPQ2 beyond test parameters down ~120cm (P windpacked hard slab on F basal facets and depth hoar).
Wet loose and rollerballs on NW Gordon Lyon:
SoFo from GL: