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Eddy Mtns - Storm Slab

Location Name: 
Tamarack flat
Mt Eddy
Date and time of observation: 
Mon, 02/27/2023 - 1:01pm
Observation made by: 
Red Flags:
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain

Location Map

96067 Mount Shasta , CA
United States
41° 21' 56.5344" N, 122° 31' 52.0716" W
California US

Snowpack Observations


Today we embarked on a mission into the Eddy mountains to observe storm conditions and assess for instabilities within the new snow. Our suspicions were confirmed with a storm slab releasing a foot deep from the weight of a single rider on a convex roll-over. Test slopes displayed shooting cracks and blocking underfoot. Over a foot of new, dry snow resting atop a thin crust from the previous storm's interface was encountered. The dry snow was easy to move and sluff off steep terrain. No major sign of wind loading below treeline was observed, though winds blew small amounts of snow around. Near treeline consistent moderate to strong southwest and westerly winds were ripping over ridge tops and through exposed areas, loading snow onto leeward slopes. Snowfall rates of one inch per hour persisted through the majority of the outing. No other signs of avalanche activity or snowpack instability were observed. 

  • Observation Location: Mount Eddy range 
  • Elevation: 6,600 feet
  • Date: 2032.02.27
  • Time: 0100
  • Observer: E.Falconer 
  • Sky Conditions: Overcast (OVC) | Obscured (X)]
  • Current Precipitation: Type - SN  Rate -  S2 
  • Air Temperature: 21 °F
  • Surface Penetration: Ski penetration (PS) = 10 in (25 cm), boot penetration (PF) = 40 in (100 cm)
  • Total Snow Depth (HS): 140in (355 cm)
  • 24-hour New Snow Depth (HN24): 10 in (25 cm)
  • 24-hour New Snow Water Equivalent (HN24W): 0
  • Wind Direction: SW | W 
  • Wind Speed: Moderate (M), 17-25 mi/hr, small trees sway | Strong (S), 26-38 mi/hr, whole trees in motion 
  • Column & Block Tests:



  • skier triggered storm slab over a foot deep on convex roll-over, below treeline on a north aspect
  • Snowfall amount and structure from the previous (Nov 23&24) storm and the current (Nov 27th) storm. 55 cm total with slight crust at storm interface
  • Fragile 2 cm crust under a foot of freshly fallen snow
  • Very thin, very fragile crust, can hardly feel. But its on most aspects other then due north
  • Dry-loose snow sluffing. Below treeline
  • Shooting crack underfoot. Below treeline
  • One inch-per hour snow fall rate
  • Conditions on a north facing slope near treeline
  • Conditions below treeline

Weather Observations


Cloud Cover: 
100% of the sky covered by clouds
Blowing Snow: 
Accumulation rate: 
Greater than 1 in. per hour
Air temperature: 
Below Freezing
Air temperature trend: 
Wind Speed: 
Wind Direction: