Recap of Storm and Snowpack

Location Name: 
Recap of Storm and Snowpack
Region: 
Williams Lake Area
Date and time of observation: 
Mon, 12/19/2016 - 11:48
Location Map: 
United States
36° 33' 55.2384" N, 105° 26' 30.786" W
US


Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Obvious avalanche path

Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Another beautiful day after the storm with more cold temps.  Cold temps have really dried out the snow with good quality low density snow on the surface.   Travel is incredibly supportable and things are starting to fill in down low with better skiing at lower evelations even in the trees.  We are posting two videos today giving you an idea of what we are seeing out there.  Naturals have occured throughout our backcountry.  It appears most of the avalanche activity occured Saturday Morning with the frontal passage and intense burst of snow that had graupel in it.  We can tell this from debris only being covered by 10 to 20 cm of low density snow that fell Saturday afternoon when the temperatures dropped.  There is a graupel layer that fell Saturday Morning, if you were up or half awake around 4 AM you might have heard Thunder in the town of Taos, signaling a shift from Warm and Cold Air and produced graupel here in town.  This Graupel layer is widespread but seems to be reactive only in specific areas where it has pooled.  A pronounced sun crust/melt freeze crust at lower elevations formed Thursday before the storm when we had near record temperatures and delineates the storm snow from old snow.   

Strong solar radiation and frigid temps are really driving temperature gradients in the snowpack.  See Snowpit for a temp profile.  Graham will talk about this in tomorrow's forecast.  A near surface facet layer is forming on the surface again and bares watching before this next storm.  

In all the crowns we've been too we are seeing a common theme of avalanches failing on small grained facets above a supportable crust about 4 to 10" above the ground.  We have seen a couple of crowns especially southerly aspects that have run on just the sun crust that formed Thursday before the storm, but for the most part this is the layer of concern (See Videos)  

Propagation during this avalanche cyle was incredible for this area and crowns on different aspects and elevations are showing a similar problem of small grained facets near the ground.  Stability Tests (See Video) are indicating that this weak layer has the ability to propagate.

Snowpit or crown profile photo or graph: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
Clear
Air temperature: 
Below Freezing
Wind Speed: 
Light
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
West
Accumulation rate: 
None