BC Zone Observation Report
Tuesday, November 26, 2019 at 12:00 AM
Gunnison
Details
Date:
2019/11/26
Observer:
Ben Pritchett
Organization:
Forecaster, CAIC
Location
BC Zone:
Gunnison
Area Description:
Anthracites
Weather
Ridgeline Wind Speed:
20-30 mph
Ridgeline Wind Direction:
NW
Wind Loading:
Moderate
Temperature:
7 F
Sky Cover:
Overcast
Depth of New Snow:
18 cm
Depth of Total Snow:
80 cm
Most Significant Precip Rate:
S1 - 1 cm/hr
Weather Description:
Chilly, overcast, and windy
Snowpack
Snowpack Description:
Very weak structure overall. Biggest concern is triggering a Persistent Slab avalanche that would break near the ground in large depth hoar. Easterly-facing slopes with drifting have the most volume and most well-developed slab structure, hence greatest hazard. Above 11,000 feet the slab is just barely cohesive enough to propagate a short distance in wind-sheltered but connected terrain. At lower elevations there's not enough stiffness in the slab to be a concern. Besides the October Depth Hoar (capped with Surface Hoar), there's another weak layer worth noting. I found very large Surface Hoar beneath the current storm snow on many slopes. This layer was very touchy, but only breaking 15-20cm deep so it posed no danger at the moment. The crystals are strangely crispy, so it may remain more durable - we'll have to watch it over time. In this area, I could not find a place where I would be able to trigger a Wind Slab avalanche that did not have a persistent weak layer below.
Avalanches
Avalanche Description:
Watched another party nearby trigger a small slab in a steep roll in widely spaced forest.
Date
Location/Path
#
Elev
Asp
Type
Trig
SizeR
SizeD
2019/11/26
†
Anthracites
1
<TL
NE
SS
AS / u
R1
D1
Date:
2019/11/26 (Estimated)
Observer:
Ben Pritchett
Organization:
Forecaster, CAIC
Area Description:
Trees just west of 7-bowl
Landmark:
Anthracites
Elevation:
11600 ft
Weak Layer Grain Type:
Depth Hoar
Average Crown:
50 cm
Media
Images