Graupel keeps falling on my head


Whilst walking my dog Indy this afternoon, I noticed the snow change from fluffy crystals to small hail like snow. Looking a bit like Styrofoam balls they stuck to Indy's back and head. This type of precipitation is called Graupel.

Graupel is formed when the temperature in the clouds drops to around -40°C. Under the right atmospheric conditions snow crystals collide with super-cooled water droplets. The water then freezes around the snow crystal, forming the small balls you see on Indy's head. Hail is very hard and icy, whereas graupel is a soft and almost sticky kind of snow.

It is important to notice graupel as it can be a contributing factor to avalanches. The little balls stack up on the snow like a layer of marbles. When the weather turns back to snow this layer becomes buried in the snowpack. As you can imagine it then becomes very easy for the snow to slide off this 'layer of marbles'. Fortunately, graupel quickly begins to compact and loose its shape, stabilising in the snowpack after a couple of days. So just be aware and avoid any steep slopes for the next two days, the graupel is lurking!