Northern Whitefish Storm Snow

Location Name: Northern Whitefish Range Observation date: Thursday, January 9, 2020 - 18:00	Is this an Avalanche Observation: Yes

Observation made by: Professional Observer

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Quick Observation

Today we took the snowmobiles out in the Red Meadow drainage.

We found 18+ inches of new snow on the road.
At elevations above 5500' there was evidence of plenty of wind transport on N and NE slopes.
Protected slopes had 18-24 inches of 4F, right-side-up new snow. This new snow sits atop a thin freezing rain crust that was constructed over the holidays (12/31 crust). Below the rain crust we found buried surface hoar. This layer failed with hard force in an Extended Column Test (ECTP21).
We did not find the third, shallower, thin rain crust that has been found further south.
Clear skies dominated the day with temps in the teens.
In the country that we could see there was no evidence of recent avalanches, other than an 8-10 inch storm slab that looked to have pulled out Monday.
Winds were calm, with the exception of the higher peaks in Glacier NP where we saw active blowing snow through midday.

Snowpack, Avalanche, Weather Images:

Travel Details

Region:

Whitefish Range - Northern (north of Coal Creek)

Route Description:

To 5600'

Activity:

Snowmobiling

Snowpack Details

Snowpack and Weather Details:

Terrain

Elevation of observation:

3500-5000 ft

5000-6500 ft

Aspect(s) of observation:

Red Flags:

More than a foot of new snow or heavy snowfall rates (>1"/hr)

Persistent Weak Layers:

Surface Hoar

Facets or Faceted Crust

Buried

Total Snow Depth:

215

More comments about the snowpack and weather:

clear with increasing clouds throughout the day. Temps were dropping. Right side up snow was found in sheltered areas. Wind affected snow was stiffer and our sleds didn't sink in as deep. We had localized cracking in wind affected snow on the very short skin to where we dug our snowpit.

Blowing Snow:

None

Wind Speed:

Calm (No air motion)

Air temperature:

Below Freezing

Snow line:

below valley

Sky Cover:

Increasing clouds

Highest Precipitation Rate:

No Precipitation (NO)

Avalanche Details

Avalanche Details:

Date and Time of Avalanche:

Sunday, January 5, 2020 - 06:15

Number of avalanches:

Avalanche Type:

Soft Slab

Failure Plane/Weak Layer:

Within storm snow

More information or comments about the avalanche:

This looked to have been during the storm, probably monday.

Trigger

Trigger:

natural

Terrain

Start Zone Slope Angle:

Aspect:

Southeast

Starting Elevation:

near-treeline

Size

Destructive Size:

D1 Relatively harmless to people.

Relative Size:

R1 Very Small

Crown Height:

Less than 1 ft

Avalanche Length (Vertical Run):

250ft.

Avalanche Width (Average width):

100ft.

People Involved

Number of people caught:

Number of partial burials:

Number of full burials:

Avalanche Location:

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