| Trigger | Foot Penetration | Remote Trigger | Unknown |
| Avalanche Type | Soft Slab | Aspect | North |
| Elevation | 4400ft | Slope Angle | 37deg |
| Crown Depth | 20in | Width | 40ft |
| Vertical Run | 300ft |
Avalanche: Hatcher Pass
Location: Nose Bleed
Road observations
Toured from IMB > Microdot > Nose Bleed
Avalanche Details
SS-AFr-D1.5-I new snow failing on old snow layer of NSFs, remotely triggered on foot
Also SS-ASc-D1-I x2 40-50cm deep x 10'wide x 15' long
Many slab and dry loose avalanches W>N>E, 2500'-4500'
Obvious signs of instability
| Recent Avalanches? | Yes |
| Collapsing (Whumphing)? | Yes |
| Cracking (Shooting cracks)? | Yes |
Observer Comments
Multiple recent natural slab avalanches, W>N>E, 2500-4500' (mid to upper elevations), D1-2, during and shortly after 4/16-17 storm
Recent natural loose dry on all aspects but predominantly on northerly aspects on slopes 35 degrees and steeper, with more significant and larger loose dry on 40 degrees and steeper, D1.5. Example: All of Rae Wallace northerlies sluffed out. See picture.
Recent natural wet loose on steep southerly aspects failing on crusts, D1-1.5
Weather
50cm new snow 4/16-17
4500' H29F, 3500' H36, greenhousing, high humidity
broken skies
calm winds observed up to 4500', no flagging observed
Snow surface
moist snow
Snowpack
New storm slabs sitting on the old snow surface of NSFs on northerly aspects sensitive to human triggers on unsupported, steep convex slopes, 40 degrees and steeper. Northerly aspects on 4068, on slopes approximately 38 degrees, saw a good amount of skier traffic with no avalanche activity.
In most other locations, and on slopes 35 degrees and less, storm slabs were not reacting to human triggers.
The new snow was very warm today (hot pow) and appeared to be bonding to the old snow surface. Cold temps this evening should improve stability for tomorrow.
Loose wet avalanches were observed on steep southerly aspects, failing on old crust surfaces.
Loose dry avalanches were widespread and large on slopes 40 degrees and steeper.
Rae Wallace, N, 3800'-4500', most steep northerlies had widespread loose dry avalanches, D1.5
Microdt, S, 4400', recent natural wet loose failing on old crust surface, D1
April Bowls lower roll, Bennets Ridge, N, approx. 3800', natural or remotely triggered storm slab avalanches, D2
Delia Creek, E, 3200', recent large natural dry loose avalanche, D1.5
Microdot, NW, approx. 3800', recent natural slab avalanche, D1, possibly failing this morning
Microdot, NW, 3800', recent natural storm slabs, D1.5
Rae Wallace, N, 4250', recent natural storm slab, D2
Nose Bleed, N, 4400', Crown from foot penetration remotely triggered storm slab avalanche, D1.5
Nose Bleed, N, 4400', foot penetration remotely triggered storm slab, runnout and debris. Note ski tracks occurred after avalanche was triggered.