Pro Field Report

Basic Information

Observation Details

Observation Date:
January 11, 2023
Submitted:
January 11, 2023
Observer:
SAC - Davis, Pruess
Zone or Region:
Soldier and Wood River Valley Mtns
Location:
Salt Bowns Road (All aspects, 5,800-8,300')

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced
Numerous <D2 wind slab avalanches at middle and lower elevations. Some near Bellevue and a couple dozen more in the Soldier foothills. One D2 near Little Smoky Dome. One rider triggered D1.5/D2? (see below). Cracking under recent 2' of snowfall as well as in deeper weak layers buried 2.5' down.

Snow Stability

Stability Rating: 
Fair
Confidence in Rating: 
High
Stability Trend: 
Improving

Bottom Line

2' of recent storm snow + last night's NW wind caused numerous small natural avalanches. Wind slabs were reactive today. Riders triggered a wind-loaded slope from above. Weak snow beneath these slabs appears to be most sensitive on shaded slopes. Cracking in older weak layers 2.5' below the surface suggests that triggering a very large avalanche remains a possibility in steep terrain.

Media/Attachments

Large slab avalanche on Little Smoky Dome. E aspect at 9,300'.
Small, low elevation wind slab avalanches on the hills NW of Bellevue.
Small, low elevation wind slab avalanches on E aspects near Soldier Ck.
Wind affect at low elevations of Soldier Ck.
Riders in the Soldier Mtns remotely triggered this wind slab avalanche from atop the ridge. SE aspect at 8,200'. This and many nearby slopes showed signs of heavy wind-loading from strong NW wind early in the morning on Jan. 11th.
Snowmobiles produced this crack and small slab release on a N-facing slope at about 7,200'. The slab released on 4 mm surface hoar. The lines above and below the failure layer also harbored weak layers of 4-6 mm surface hoar.
Riders in the Soldier Mtns remotely triggered this wind slab avalanche from atop the ridge. SE aspect at 8,200'. This and many nearby slopes showed signs of heavy wind-loading from strong NW wind early in the morning on Jan. 11th.
Slope cuts with a snowmobile released two slab layers. One about a foot thick, and another 2.5 feet thick. The lower failure layer was surface hoar between two closely spaced crusts (center of crystal card). NNE aspect at about 6,900'.
Slope cuts with a snowmobile released two slab layers. One about a foot thick, and another 2.5 feet thick. The lower failure layer was surface hoar between two closely spaced crusts. NNE aspect at about 6,900'.

Advanced Information

Weather Summary

Cloud Cover:
Mostly Sunny
Temperature:
Low 20s
Wind:
Moderate , NW
New/Recent Snowfall:
HST since (1/5) = 30-55 cm

Mostly sunny skies over the Soldiers. Some mid-level clouds at times, particularly in the W. Smokys and along the southern Smoky Crest near Dollarhide. Light to moderate NW wind. Some blowing snow was observed in the Soldier alpine but no snow moving at middle elevations. Warm direct sun released roller balls in steep SW and S in the mid-afternoon.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Jan 10, 2023
(+/- 1 day) 		Little Smoky Dome
E 9300ft 		D2 N-Natural
Large slab avalanche on Little Smoky Dome. E aspect at 9,300'.
Report
1 Jan 11, 2023 10:45 am
(Exact) 		Between N. Fork and S. Fork Soldier Ck
SE 8200ft 		D1.5 HS-Hard Slab AM-Snowmobile
r-Remote
Riders in the Soldier Mtns remotely triggered this wind slab avalanche from atop the ridge. SE aspect at 8,200'. This and many nearby slopes showed signs of heavy wind-loading from strong NW wind early in the morning on Jan. 11th.
Riders in the Soldier Mtns remotely triggered this wind slab avalanche from atop the ridge. SE aspect at 8,200'. This and many nearby slopes showed signs of heavy wind-loading from strong NW wind early in the morning on Jan. 11th.
Report
Little Smoky Dome
Between N. Fork and S. Fork Soldier Ck

Clouds prevented any effective glassing into the W. Smokys or the southern Smoky Crest near Dollarhide.

Snowpack Observations

WSW @ 6,800', HS = 140 cm, Planar open slope: Snowpack tests produced several, repeated ECTNs in the upper 45 cm of the snowpack on small facets and near crusts. The snowpack grades from F at the surface to 1F near the base. A 35 cm 4F layer of rounding large facets sits at the ground. ECTXs on and below (12/26) dn 55 cm.

NNE @ 6,900', Steep sheltered slope: We dug near a sled-triggered crack. The deeper failure was down 80 cm on (12/19?) which presented as surface hoar on a melt-freeze crust. Shallower failure was down 25 cm within recent storm snow. (see photos).

N @ 7,200', HS = 130 cm, steep sheltered slope: We dug near a small sled-triggered roadcut. The slab failed on 1 of 3 layers of surface hoar found in the upper 45 cm of the snowpack. (see photo).

SSW @ 6,800', HS = 108 cm, 30 deg short open slope: The upper 10 cm of the snowpack was wet. ECTNs in the upper 30 cm of recent snow. No surface hoar here. ECTXs near and below (12/26).

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wind Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 30 to 80 cm, (1/10)
Comments: There were some thick crowns out there but most slabs tapered quickly away from ridge lines. These were reactive today but I'd assume that they heal fairly quickly given the relatively friendlier sunny slopes that they formed on.
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 30-50 cm, (1/8)
Comments: Between stubborn and reactive. I've found this layer as buried surface hoar in Banner (1/10) and in the Soldiers. It seems most likely to be found in sheltered, shaded areas. I didn't find it on sunnier aspects today and it was spottier as I climbed into windier locations on Copper Mtn yesterday.
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Layer Depth/Date: 60-80 cm
Weak Layer(s): Dec 19, 2022 (FC)
Comments: 12/19 and 12/26 are close together here. Snowmobiles triggered a small road cut that cracked down to these layers. They are still <1m down in this area and could produce a very large avalanche in the right terrain.

Terrain Use

We avoided avalanche terrain.