Moosh in the booosh

Location Name: 
Forecaster observation: Marias Pass
Observation date: 
Wednesday, April 10, 2019 - 16:00
Is this an Avalanche Observation: 
Yes
Observation made by: Forecaster

Location

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Quick Observation

Traveled to Marias Pass area to check out the effects of Tuesday's wraparound storm. We climbed to about 6100 feet; no obs from obove there due to poor visibility.

  • The storm dropped 6-16" (2+" SWE) of moist. dense snow near the Continental Divide. Snow totals tapered off rapidly west of the pass, though it looked like snow fell above ~5600 feet near Essex.
  • The storm wasn't accompanied by much wind. We saw no signs of drifted or blowing snow. Of course, it would have taken a spatula to move this storm snow.
  • We found ~1/2 dozen natural wet loose slides that ran on steep (~40 degrees) creekbanks. Stomping around on short test slopes confirmed that it would be easy to trigger wet loose slides that would entrain significant debris. Near 5000 feet, they could gouge into the wet melt freeze grains below the storm snow, making them more dangerous.
  • Below the storm snow is a 1-5 cm thick refrozen crust of melt freeze grains or rain crust. We could pry the storm snow off at the interface ( planar shear) but it did not fail in stability tests.
  • The snow below the old/ new snow interface is moist rounds and refrozen percolation tubes on northerly slopes, or mushy soft melt-freeze grains.
  • What we saw suggests storm slabs 6-18" thick might exist at upper elevations (above 7000 feet?) where the storm dropped dry snow. 

Skiing was tips-up,  wide feet to let the wedge of snow pass between your boots. 

Snowpack, Avalanche, Weather Images: 
Snowpack, Avalanche, Weather Videos: 

April 10, 2019 - Wet Blanket

Travel Details
Region: 
Flathead Range - Marias Pass/Skyland
Snowpack Details
Snowpack and Weather Details: 
Hide Terrain
Elevation of observation: 
5000-6500 ft
Aspect(s) of observation: 
N
NE
W
NW
Red Flags: 
More than a foot of new snow or heavy snowfall rates (>1"/hr)
Rain on snow
Rapid or prolonged warming
Rollerballs / pinwheels
New Snow in the past 24 hours: 
15.00in.
Total Snow Depth: 
155 cm
More comments about the snowpack and weather: 
Snowline this morning varied from over 6000 feet near West Glacier to ~5600 feet near Essex to ~4500 feet near Marias Pass. Snow totals ranged from a few inches around Fielding to 15+" near and east of the Continental Divide. Based on snow in trees, little wind accompanied the snowfall. Skies were mostly cloudy with a brief shot of sun about midday. Winds remained light and easterly. Rain showers started mid-afternoon, light at the field site but moderate on the drive home around Nyack Flats. Rain line appeared to be higher than the morning's snow line.
Blowing Snow: 
None
Wind Speed: 
Light (Twigs in motion)
Wind Direction: 
Northeast
Air temperature: 
Above Freezing
Snow line: 
7000 feet
Sky Cover: 
Mostly Cloudy (BRK)
Highest Precipitation Rate: 
Very Light Rain (RV)
Avalanche Details
Avalanche Details: 
Date and Time of Avalanche: 
Wednesday, April 10, 2019 - 10:00
Avalanche Type: 
Wet Loose
Failure Plane/Weak Layer: 
Old snow
More information or comments about the avalanche: 

Natural Wet Loose avalanches in the new snow on steep slopes above creek either side of Marias Pass.

Hide Trigger
Trigger: 
natural
Hide Terrain
Aspect: 
Northwest
Starting Elevation: 
5200 feet
Hide Size
Destructive Size: 
D1 Relatively harmless to people.
Relative Size: 
R2 Small
Avalanche Length (Vertical Run): 
40ft.
Hide People Involved
Number of people caught: 
0
Number of partial burials: 
0
Number of full burials: 
0
Avalanche Location: 
Date and Time of Avalanche: 
Tuesday, April 9, 2019 - 12:00
Avalanche Type: 
Wet Loose
Failure Plane/Weak Layer: 
New/old snow interface
More information or comments about the avalanche: 

Slightly older Wet Loose slide in eastmost of 3 gullies (Larry; 3 Stooges) between Tranquil Basin trail and Silver Stairs. Looked to have run in last 24-36 ours. 

Hide Trigger
Trigger: 
natural
Hide Terrain
Aspect: 
Northwest
Starting Elevation: 
below-treeline
Hide Size
Destructive Size: 
D1.5
Relative Size: 
R1 Very Small
Avalanche Length (Vertical Run): 
200ft.
Hide People Involved
Number of people caught: 
0
Number of partial burials: 
0
Number of full burials: 
0
Avalanche Location: