Little bit of wind and a whole lot of crust

Location Name: 
Forecaster Observation - Central Swan Range
Observation date: 
Tuesday, March 10, 2020 - 14:30

Is this an Avalanche Observation: 
No
Observation made by: Forecaster

Tabs

Quick Observation

We went to the western side of the Swan Range to monitor the upper snowpack and surface conditions before the return to winter weather.

  • The big story of the day remains recently formed crusts at or near the surface. On south aspects the crust was hardest (Pencil +) and up to 6 inches thick. On northerly aspects, the crust was thicker and harder in open areas and on steeper terrain, but was 2 inches thick and 1 finger hard at most. In north facing trees, and on gentle slopes, the crust was at its thinnest, softest, and most breakable. We found only dry snow under the crusts.
  • We tested the upper snowpack on a mid elevation, northwest aspect and found no weak layers and got no test results above the crusts buried in early February.
  • We found between .5 and 1 inch of graupel on the surface in most places. The exception being where recent winds had scoured the surface.
  • Despite moderate ridgetop winds, we saw only light blowing snow because there was little snow on top of the surface crusts left to transport. We did find very isolated, very thin wind deposits just in the lee of favored ridges. Under these soft drifts was a surprisingly slick wind board.
  • We expect an increase in avalanche danger this week proportional to the amount of new snow and wind.
  • With crusts locking down the snowpack in the area, we skied very steep terrain on a variety of aspects. We were slow and cautious because the fast and hard crust has created the potential for slide for a life situation in the event of a fall in the wrong terrain. As we skinned back up a slope we made sure to set our track so as not to put us directly under larger, looming cornices.
Snowpack, Avalanche, Weather Images: 
Snowpack, Avalanche, Weather Videos: 

Swan Range. March 10th, 2020

Travel Details
Region: 
Swan Range - West Side (Flathead Valley access)
Route Description: 

To 6700'

Activity: 
Skiing
Snowmobiling
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
5000-6500 ft
Above 6500 ft
Aspect(s) of observation: 
NE
E
SE
S
SW
W
NW
Red Flags: 
Blowing snow
New Snow in the past 24 hours: 
0.00in.
Total Snow Depth: 
3m
More comments about the snowpack and weather: 
Surface crust thins out with elevation on northerlies and gets softer - to 4F. Large (6mm) graupel above the crust on mid and upper elevations, all aspects, and below the crust on upper elevation northern aspects. Test at 6200' NW aspect: ECTX, CTH SP down 65cm between the 2/5 and 2/1 crusts. Early February crusts were down a meter deep on upper elevation, NE slopes. We saw evidence of old rollers on northerly slopes at middle elevations, so that snow had previously transitioned to at least moist.
Blowing Snow: 
Light
Wind Speed: 
Moderate (Small trees sway)
Wind Direction: 
West
Air temperature: 
Below Freezing
Snow line: 
3800'
Sky Cover: 
Mostly Cloudy (BRK)
Highest Precipitation Rate: 
No Precipitation (NO)