Observation: NWAC Forecaster

All Observations

Basic Information

Observation Details

Observation Date:
January 20, 2023
Submitted:
January 20, 2023
Observer:
NWAC Forecaster - Josh Hirshberg, Joe Dellaporta
Zone or Region:
East Central
Location:
Blewett Pass, Windy Knob (SW-W-N-NE, 3880-5920ft)

Signs of Unstable Snow

Recent Avalanches? 
None Observed
Cracking? 
Isolated
Collapsing? 
None Experienced

Media/Attachments

Profile. Sudden test results, tho no propagation just below the MLK crust (CTE(SP), ECTN12 @ 90cm). Windy Knob, 5485ft, NE
Mt Rainier behind the mountains surrounding Blewett Pass.
Views of the Stuart Range, Enchantments, and mountains near Leavenworth and Blewett Pass.
A wide crack where a large cornice pulled away from the ridge during the 1/13 rain event. Windy Knob
A namesake feature on Windy Knob, 5920ft
A small wind loaded roll broke into a 5ft wide slab "avalanche" with a ski cut.
Snow melted away from a geothermal vent. Windy Knob, Blewett Pass
Surface hoar in a meadow. Windy Knob, 4000ft
Surface hoar in a meadow. Windy Knob, 4000ft

Advanced Information

Weather Summary

Cloud Cover:
Clear
Temperature:
14°F
Wind:
Calm

Clear, cold morning. Light variable breeze a

Evidence of cornice fall and wet avalanches to D2 in steep near treeline terrain (N-NW, Windy Knob and Diamond Head) during the 1/13/MLK rain event

Snowpack Observations

Surfaces and upper snowpack:
Well-developed surface hoar in open terrain, though isolated elsewhere.
Light wind effect near treeline, though slabs are trending to stubborn
Steep south aspects were slightly warming at 11a
10-15cm of recent snow over the MLK crust

We didn't find evidence of the 1/4 buried surface hoar. Profile revealed a generally strong snowpack with crusts and frozen melt forms throughout. Noted weak layers were ↓20cm below the MLK crust , ↓35cm above the Xmas crust, ↓92cm on basal facets

Profile 5,485ft, NE, Windy Knob
HS 110cm
110-95: F hard, FCsf (1.0mm)
95-90: K hard, MFcr, MLK crust
90-85: 4F hard FCxr (0.5mm), CTE(SP), ECTN12 @ 90cm
85-75: 4F+ hard, FCxr(0.5mm), CTH (brk) @ 77cm
75-67: K hard, MFcr, Xmas crust
67-62: 1F hard
62-55: 4F+ hard
55-37: P hard, MF
37-20: 1F hard
20-18: P hard
18-0, 4F+ hard, FCxr (2.0mm)

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
 Comments: Isolated NTL
Persistent Slab
Isolated
Specific
Widespread
 Unknown
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Weak Layer(s): Jan 4, 2023 (SH)