Vail & Summit County
SnowpackAnonymous · Jan 27, 2014 · Vail & Summit County
Weather
Bluebird. T near-below 0C, cool above treeline where light-moderate NW winds kept people and snow surface chilled.
Snowpack
<> NE slopes at/below treeline provided fantastic recycled powder skiing even in tight trees. The strong (1F) mid pack was supportive. No instability signs observed. A quick pit (near-below tl, NE, 28dgr, HS140cm, wide open glades below ridge of Chief Mountain) showed weak basal depth hoar- MOD reactive on DT with sudden pop (a "deep ECT", showed full sudden propagation at MOD indicating that a large trigger is necessary where slab is thick and stout, but in thinner areas, fracture initiation by a skier and propagation propensity are still present. <> S slopes above treeline overall had a thin snow depth except for cross loaded features. The surface consisted of a hard wind crust (1F to P) several inches thick; at times, skis broke through into the softer layer underneath (faceted df). A quick pit (near-above treeline at 11,800ft, S, 30dgr, HS155cm) produced PST85/100 down 128cm on an old half inch P-hard melt-freeze crust, but PST40/100 immediately below that crust in basal dh, indicating that a large trigger is necessary where slab is thick and stout, but in thinner areas, fracture initiation by a skier and propagation propensity are still present. Three more instabilities in the mid and upper snowpack were observed but not tested (stacked hard slabs separated by thin nsf; broke clean when dropping the PST column). <> Currently, the most suspicious areas to trigger a Persistent Slab or Deep Persistent Slab are very steep non-uniform slopes on N-SE at and above treeline - CAUTION: Many such slopes have avalanched during the last cycle. While those start zones often have only partially refilled, strong and persistent winds have created start zones further down the track. Before committing to a very steep slope with evidence of recent avalanche activity, it is important to verify the lack of sufficient refill in the normal start zone as well as a new start zone further down its track!