Snowsafe Blog

How to Dig a Snow-pit ❄️

A snow-pit is a trench that exposes a vertical section of snow between the carpet of snow and the ground beneath. The purpose of a snow pit is to reveal layers of snow for study. 

Why do I need to dig snow-pits? 

Snow-pits allow you to study the characteristics of the snow in a particular area. Most people dig snow pits as a means of assessing the safety of the snow in a specific area and assessing avalanche risks.

As time goes by, snow accumulates in layers. These layers are not all the same but have marked physical differences.

The way the snowpack develops can have a profound effect of the risk posed, with some structures putting the snow at higher risk of an avalanche than others. 

How to dig snow-pits 

1. Scan an area with your avalanche probe to see how deep the snow is and to find a weak layer in the snow.
2. Check that your snow-pit faces north if you are in the northern hemisphere and south if you are in the southern. It’s vital that the sun’s rays cannot melt the exposed section of snow in your snow pit. 
3. With your avalanche shovel cut out a column of snow, 90 cm wide and 30 cm up the slope, you can measure this with your snow probe.
4. insert your probe into the corner of your snow-pit and use a cord to cut out the snow.
5. Once the snow is cut out place your shovel blade on top of the column and tap 10 times from the wrist, 10 times from the elbow and 10 times from the shoulder, harder and harder until you initiate a fracture. 
6. Finally, when tapping lightly, if the snow propagates a fracture this is capable of an avalanche. 

Checkout the video below on a simple way to dig a snow-pit: 

Should I dig snow-pits in more than one area?

The answer depends on how the characteristics of the area change. If you believe that there are substantive differences between one area and another, then digging more than one pit might be necessary to give you a full answer on the weakness of the snow. 

How to test snowpack stability 

• Measure the temperature of the snowpack. The temperature of the snow can provide information about its stability. Measure the temperature at the ground to the nearest 0.1 C, and then in 10 cm increments up to the surface. 
• Make a visual inspection. Look at the wall of snow in front of you. Icy layers will appear shiny and pebbly. Soft snow is not as reflective. 
• Use the naked finger test. The naked finger test involves running your finger over the snow and feeling for differences in texture and consistency. Soft texture indicates a loose snowpack, whereas hard suggests ice.

What is Compression Test? 

The compression test is where you isolate a square foot of snow and then place the blade of a shovel flat on top. Tap on the shovel harder on the shovel blade until the column falls.

Start with easy taps using your wrist and then progress onto hard taps using your elbow and then shoulder for the movement. If the snow falls under easy taps, this suggests that it is unstable.

What is an extended column test? 

Select a block a yard wide and a foot deep. Then tap on either side of the block with increasing firmness, just like the compression test, to see whether the block fails.

If it fails quickly or fractures spread out across it, then it is a warning that the snowpack might be unstable. 

What’s the best shovel & probe for digging snow-pits? 

All kinds of brands make snow shovels. The best include the Ortovox Pro Alu III, the Terrawest Core Light.

For probes its simple, a solid 240 centimetre probe will help you dig a snow-pit, we highly recommend the Terrawest Core 240 Probe. 

Snowsafe Blogs:

It’s important to stay safe and have the correct training when skiing or snowboarding off-piste please check out further blogs below : 

• Off-Piste Equipment Checklist 
• Top tips for surviving an Avalanche
• Avalanche Safety Courses
• History of Avalanche Transceivers and How they have Evolved 
• What are the differences between the BCA Tracker, Tracker 2, Tracker 3
• Could there be an app on your phone that is an Avalanche Transceiver?
   
• Difference Between Ortovox Zoom+, 3+ and S1+ Transceivers?
• Boy,12, Buried in La Plagne Avalanche for 40 Minutes

If you would like to feature a blog about your organisation or experience in the snow please feel free to contact us on info@snowsafe.co.uk or 01273 003925. We are happy to take guest blogs linking back to your website.