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Wind slab development in the Apgars
Location Name:
Forecaster Observation - Apgar Range, GNP
Observation date:
Saturday, December 29, 2018 - 15:15
Is this an Avalanche Observation:
No
Observation made by:
Forecaster
Location
Tabs
Quick Observation
Enjoyed a short day off tour observing surface slab development in the Apgar Range.
Overnight snow amounts of 3" at 4000' and ~ 6" at 6000'.
Impressive wind transport from moderate to strong winds. Our skin track filled in rapidly between 4500' and 6000'.
Cracking underfoot was the norm in areas affected by the wind. Shooting cracks up to 15' were frequent on open wind loaded slopes above 5500'.
The surface slab thickened and became increasingly tender throughout the day. This slab rests on low-density snow.
Snow falling throughout the day became increasingly dense forming an upside-down snow surface in sheltered terrain.
Snowpack, Avalanche, Weather Images:
Travel Details
Region:
Glacier National Park - Apgar Range
Snowpack Details
Snowpack and Weather Details:
Terrain
Elevation of observation:
3500-5000 ft
5000-6500 ft
Aspect(s) of observation:
E
SE
S
Red Flags:
Shooting cracks
Blowing snow
Persistent Weak Layers:
Not observed
New Snow in the past 24 hours:
6.00in.
More comments about the snowpack and weather:
I did not dig a pit because I was only interested in surface instabilities. The temperature increased throughout the day which resulted in a rain/snow mix at the trailhead at 1630.
Blowing Snow:
Moderate
Wind Speed:
Moderate (Small trees sway)
Wind Direction:
West
Snow line:
3500'
Sky Cover:
Obscured by fog, etc (X)
Highest Precipitation Rate:
Moderate Snowfall (S2)
Avalanche Details
Avalanche Details:
Date and Time of Avalanche:
Saturday, December 29, 2018 - 19:15
