Heavily rimed new snow, often shaped like little Styrofoam balls.
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Graupel:

Graupel is that Styrofoam ball type of snow that stings your face when it falls from the sky. It forms from strong convective activity within a storm (upward vertical motion) caused by the passage of a cold front or springtime convective showers. The static buildup from all these falling graupel pellets sometimes cause lightning as well.

It looks and behaves like a pile of ball bearings. Graupel is a common weak layer in maritime climates but more rare in continental climates. It's extra tricky because it tends to roll off cliffs and steeper terrain and collect on the gentler terrain at the bottom of cliffs. Climbers and extreme riders sometimes trigger graupel avalanches after they have descended steep terrain (45-60 degrees) and have finally arrived on the gentler slopes below (35-45 degrees)--just when they are starting to relax. Graupel weak layers usually stabilize in about a day or two after a storm, depending on temperature.



Graupel Summary:

Caveat:
Graupel tends to become faceted easily when subjected to a strong temperature gradient, in which case, graupel produces avalanches much more persistently.

Looks like:
Little Styrofoam balls

Feels like:
Stings your face

Behaves mechanically:
Like ball bearings

Distribution pattern:
Rolls off of cliffs and steep slopes and collects on gentler terrain and in pockets. Not aspect or elevation dependent.

Persistence:
Sstabilizes about one day after deposited, depending on temperature and metamorphism

Additional Terms:
Anchors Hard Slab Avalanche Slide
Aspect High Danger Sluff
Avalanche High Marking Snowpit
Avalanche Path Isothermal Soft Slab Avalanche
Avalanche Transceiver Layer, Snow Stability
Bed Surface Leeward Stability Test
Collapse Loading Starting Zone
Concave Slope Loose Snow Avalanche Stepping Down
Considerable Danger Low Avalanche Hazard Sun Crust
Convex Slope Melt-Freeze Snow Surface Hoar
Cornice Metamorphism, Snow Sympathetic Trigger
Corn Snow Moderate Danger Temperature Gradient
Couloir Persistent Weak Layers Terrain Trap
Cross Loading Point-Release Track
Crown Face Probe Trigger
Danger Ratings Propagation Trigger Point
Deep Slab Avalanche Rain Crust Upside-Down Storm
Density, Snow Remote Trigger Weak Layer
Depth Hoar Rime Weak Interface
Dry Snow Avalanche Runout Zone Wet Snow Avalanche
Extreme Danger Sastrugi Windward
Faceted Snow Settlement Wind Loading
Fracture Ski or Slope Cut Wind Slab
Glide Skinning, Skin Track Whumpf
Graupel Slab