Pro Field Report

Basic Information

Observation Details

Observation Date:
March 12, 2023
Submitted:
March 12, 2023
Observer:
SAC - JP Preuss
Zone or Region:
Banner Summit
Location:
Lola Creek (SE-NE; 6500-8600')

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
None Experienced
Collapsing? 
Isolated
One large collapse on the ridgeline of a previous skin track from yesterday.

Bottom Line

The snowpack in this location looks stronger than the other zones. Though, these are limited observations, I observed less natural activity and other signs of instability. Snow pit structure and tests pointed towards good stability.

Media/Attachments

(3/12/23) Large cornices near Copper Mountain.
(3/12/23) Cracks from a cornice beginning to calve from the ridgeline.

Advanced Information

Weather Summary

Cloud Cover:
Mostly Cloudy
Wind:
Light , SW
New/Recent Snowfall:
HST 30cm settled

Skies were broken through the mid-afternoon with enough solar gain to moisten south facing slopes, which were dry snow in the morning. Later in the day, the skies became overcast with a passing light flurry, bringing no accumulation.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Mar 10, 2023
(+/- 1 day) 		Cabin Creek
NE 9400ft 		D3 N-Natural
(3/12/23) A very large avalanche occurred on a NE slope at 9400' in the Cabin Creek drainage. The crown appears to be about 3-5' deep.
Report
5 Mar 10, 2023
(+/- 1 day) 		Beaver Creek
NE 9600ft 		D2 N-Natural
(3/12/23) Numerous crowns and debris piles across this basin. All are primarily facing NE from 9000-9800' above Beaver Creek.
Report
4 Mar 10, 2023
(+/- 1 day) 		Frenchman/Smiley Creek Divide
N 9100ft 		D2 N-Natural
(3/12/23) Many large avalanches on N-NE slopes around 9100'.
(3/12/23) Many large avalanches on N-NE slopes around 9100'.
Report
5 Mar 10, 2023
(+/- 1 day) 		Vienna Peak
NE 9900ft 		D2 SS-Soft Slab N-Natural
(3/12/23) Many large avalanches in the Vienna basin.
Report
1 Mar 11, 2023
(+/- 1 day) 		Smiley Creek near Vienna Peak
NE 9100ft 		D2 SS-Soft Slab N-Natural
(3/12/23) A very large avalanche on a NE slope at 9600' in the Smiley Creek drainage.
Report
1 Mar 11, 2023
(+/- 1 day) 		Smiley Creek near Vienna Peak
NE 9600ft 		D3 N-Natural
(3/12/23) A very large avalanche on a NE slope at 9600' in the Smiley Creek drainage.
Report
4 Mar 10, 2023
(+/- 1 day) 		Frenchman Creek
E 9800ft 		D2 N-Natural
(3/12/23) Many large avalanches failing on various weak layers on E-SE slopes.
Report
1 Mar 10, 2023
(+/- 1 day) 		Vienna Peak
N 9500ft 		D2 N-Natural
(3/12/23) Several large avalanches occurring on E slopes in Mill Gulch.
Report
2 Mar 10, 2023
(+/- 1 day) 		Mill Gulch
E 9400ft 		D2 N-Natural
(3/12/23) Several large avalanches occurring on E slopes in Mill Gulch.
Report
2 Mar 10, 2023
(+/- 1 day) 		Imogene Peak
E 9800ft 		D2.5 N-Natural
(3/12/23) A very large avalanche occurred on an E slope at 9800' on Imogene Peak. Another crown is visible on the right side of the drainage.
Report
1 Mar 11, 2023
(+/- 1 day) 		Hell Roaring Creek
SE 10000ft 		D2.5 SS-Soft Slab N-Natural
(3/12/23) A very large avalanche occurred on a SE slope at 10,000' in the central Sawtooth mountains.
Report
1 Mar 10, 2023
(+/- 1 day) 		Williams Peak
NE 9800ft 		D2 N-Natural
(3/12/23) A large avalanche on a NE slope at 9800' on Williams Peak.
Report
2 Mar 10, 2023
(+/- 1 day) 		Meadow Creek
E 9200ft 		D2.5 N-Natural
(3/12/23) A few deep debris piles can be seen in this photo.
(3/12/23) A very large avalanche occurred on a E-NE slope around 9200' above Meadow Creek in the Sawtooth mountains.
Report
1 Mar 10, 2023
(+/- 1 day) 		Lola Creek
SE 9000ft 		D2 SS-Soft Slab N-Natural
(3/12/23) A persistent slab avalanche on a SE slope at 9000' in Lola Creek. Based on the aspect and the appearance of the crown, this slide likely failed on a layer of facets below a melt freeze crust.
Report
Cabin Creek
Beaver Creek
Frenchman/Smiley Creek Divide
Vienna Peak
Smiley Creek near Vienna Peak
Smiley Creek near Vienna Peak
Frenchman Creek
Vienna Peak
Mill Gulch
Imogene Peak
Hell Roaring Creek
Williams Peak
Meadow Creek
Lola Creek
 #  Date Location Size Type Bed Sfc Depth Trigger Comments Photo
2 Meadow Creek
NE 8700 		D1.5 SS N-Natural
(3/12/23) Two thin crowns on a NE slope at 8700' in Meadow Creek.

I observed many D2-3 avalanches in the Sawtooth mountains and will add them to the database tomorrow.

I talked with a group of snowmobilers who saw some small avalanches on a NE slope around 9000'. They didn't have any alarming snowpit results.

Snowpack Observations

I dug three snow pits on SE slopes through each of the zone elevation bands. All of the results were within the new snow and below the most recent melt freeze crust. The new snow is upside down with wind-affect and warmer temps during the tail end of the storm. This likely won't be an issue for too long. Results from below the melt-freeze crust (30cm down) were all ECTN20s in all locations. The rain crust is down about 55cm for reference, but was glued on either side of it.

A northeast facing pit at 7600' showed a strong snowpack with no layers of concern. Storm snow measured around 30cm thick. The rain crust was down 70cm and produced ECTN23, 30 results.

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: 1-2'
Comments: I felt hollow-drumlike slabs (4F/1F) in the upper elevation down 1-2' thick, but didn't have any collapsing associated with them.
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: 35cm
Comments: Sensitivity is based on limited natural activity and snow pit results.

The natural in Lola Creek likely failed on a melt-freeze crust down a foot with some additional weight of wind-loading on the slab. It seems the persistent slab problem on south facing slopes is stubborn unless you find the right loaded terrain from the wind.

Cornices are getting very large. I witnessed cracks from cornices beginning to show signs of calving away from the ridgeline.

Terrain Use

Solo travel. Stayed out of avalanche terrain.