Avalanche

Tranquil Basin

FACFlathead Range & Glacier NP
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Quick report

Cracking
isolated
Collapsing
isolated

3-10" of new and drifted snow between canyon floor and 7500 feet. Sitting on last week's snow surfaces, which were mostly melt-freeze crusts on steeper, sun-exposed slopes and old snow on sheltered slopes. 1 audible collapse, 2 recent natural avalanches, and no shooting cracks or propagating test results. Snow felt cakey and a little dense on open, west facing slopes at upper elevation but we found no distinct wind slabs. 

1 glide ctack opening on a steep, southeasterly slope at upper elevations. 

Today's sunny breaks were strong enough to thicken the surface snow on the most open mid elevation slopes. May be a slight crust in the morning. 

Isolated short, radial cracks around skis while breaking trail. Crust breaking on soft snow below. 1 audible collapse at ~6600 feet as later skiers approached regroup point. Not loud.

Weather

Air Temp
low 20s
Cloud Cover
broken
Wind Loading
none
Recent Snowfall
T
Snow Avail For Transport
moderate amounts

Broken clouds, with strong sun when windows were open. Calm to light winds until early afternoon, then winds got gusty when convective cell moved through. A few flurries.

Snowpack

3-10 inches of new and some drifted snow between 4200 and 7500 ft. Deepest accumulations at mid elevations; windward, upper elevations scoured, with just 2-4" sitting on last Thursday's MFcr. A thin layer of near-surface facets exists at the new/ old snow interface, which made for planar breaks in most hand shear tests. Recent snow did not feel stiff enough to act as a slab. 

Test profile at 6600 ft, W slope, 26*. HS 300 cm. 20 cm F to F+ hard new/ drifted snow sitting on 3-5 cm P hard MFcr. Thin layer of NSF at interface. ECTN 16; CTM 11 SP. Below MFcr, ECTN 21, CTM 16. Generally harder with depth below, though a few slightly softer interfaces that did not fail in ECT. 

Avalanche

Size
D1 R1
Type
U
Count
2
Aspect
E
Trigger
N
Elevation
6900 ft

Small, narrow natural avalanche that broke below rocks on leeward slope. Debris did not trigger slab on slope below.