- Trip 1, Mike Spencer Pk, 3.5 miles East of Pine Creek, skied 2/3/10, 10AM-3PM, 8400-6800′ skied, N-NE aspect, 4 skiers, 4-6′ snow, sunny AM-overcast/snowing PM, temps 5AM-23, 11AM-39, 5PM-30 (from Pine Creek Basin Snotel @ 6,720′)
- Trip 2, Stouts Mt, 2 miles West of PC, skied 2/6/10, 10AM-4PM, 8600-6600′ skied, S-SE aspect, 4 skiers, 3-5′ snow, clearing AM-sunny PM, temps 5AM-27, 11AM-37, 5PM-25 (from PCBS @ 6,720′)
- Trip 3, Girls Camp Bowl, .75 miles West of PC, skied 2/6/10, 3PM-6PM, 7200-6600′ skied, NE aspect, 6 skiers, 3-5′ snow, clearing AM-sunny PM, temps 5AM-27, 11AM-37, 5PM-25 (from PCBS @6,720′)
- Trip 4, Girls Camp Bowl, .75 miles West of PC, skied 2/7/10, 11AM-1PM, 6800-6600′ skied, NE aspect, 2 skiers, 3-5′ snow, sunny AM and PM, temps 5AM-14, 11AM-30, 5PM-20(from PCBS @ 6,720′)
All of the terrain was of the same basic character; open trees, glades and drainages and of about the same slope angles, ranging from 25-40 degrees.
- Trip 1, 3 pits showed the reactive layer to be buried surface hoar 8-12″ down, sheared Q2 at 7 taps at 37 degrees, sheared Q2 in mid teens taps on 28-31 degree slopes but no propagation in extended column. The over-laying snow was newly fallen, light fluff(no slab)
- Trip 2, 2 pits showed layers and slabs but no shear by 30 taps. The surface snow was moistening with the days heat and sunlight.
- Trip 3, 1 pit showed reactive layer shearing at 7 taps.
- Trip 4, 2 pits showed reactive layer to be older buried surface hoar about 2′ deep, sheared Q2 at 25 taps
Third, the results:
- Trip 1, 2 laps skied uneventfully, no sluffs, whumps, cracking, no signs of instability
- Trip 2, 1 lap skied uneventfully, saw new, small wet slides and rollers, beginnings of wet instabilities
- Trip 3, 1 lap skied with 4 skiers triggering slab breakouts with 8-14″ crowns causing 2, 50-70′ wide slides with 200-300′ runout of debris.
- Trip 4, 1 lap skied uneventfully, no signs of new instabilities
- Trip 1, reactive layer in snowpack in the RED zone on angles above 35 degrees, in the YELLOW zone on angles less than 32 degrees. The skied terrain was mostly under 35 degrees, the slope was relatively uniform with few rollovers(convexities) and we crossed out of one minor drainage, there was no slab on the reactive layer, just fluffy new snow. The day, although warming turned overcast during the descent with little to no wind. We skied conservative lines based on the tests
- Trip 2, GREEN zone conditions in our tests but the S exposure and sun quickly warmed the snow and early sign of wet instabilities hurried us along. If we had an advantage, it is that this aspect has already been warmed and cooled several times, somewhat stabilizing the slap and it did not have the buried surface hoar found on the northerly slopes. We did cross around and over rollovers but tried to limit them, we did ski down a drainage that could have proved dangerous as a terrain trap; a little later in the day or a bit warmer and it could have been a big problem. Our route selection could have been better.
- Trip 3, RED zone with this test, slope angles averaging steeper than the first 2 trips, many rollovers and a minor drainage on left side of descent, more skiers, late on a warm day that stressed the reactive layer and it did fail on rollovers in the terrain. The fact that the skiers triggered the slides and were therefore at the top of it and that the slab was relatively thin prevented more serious consequences. They moved to an area of lesser slope angle and fewer convexities and skied out.
- Trip 4, Overnight cold temperatures settled the reactive layer into the GREEN zone on the same slopes as Trip 3. Stayed off the reorganizing snowpack on this slope and left while it was still cold.
- heed the tests results
- know the instability
- heed new stress on the snowpack, in this case rapid warming
- avoid convexities and drainages when the tests indicate RED to YELLOW conditions
I know looking at these recent, closely spaced trips with differing results and looking for patterns is helping me understand what I do well and what I need to do differently.