A Tell-Tale Sign To Watch For In Avalanche Country.

As the weather in the Northeast has gradually become colder over the last few weeks, I have noticed the soil in my garden develops into crystalized patterns such as those in the picture below:

Of course, as the weather starts to turn cooler, I naturally start to think about skiing. As these thoughts materialized recently, I realized that this crystallization follows the same process as that of surface hoar in the snow pack. Surface hoar presents, on a smaller scale than these pictures, in a very similar manner. It develops overnight when the following weather conditions exist:

• Clear sky
• No direct sunshine, or very weak sun
• Calm or light winds
• Open slope exposed to a clear sky (trees or clouds can radiate their own heat and disrupt the process)
• Humid air

If you have been fortunate enough to participate in guided backcountry skiing, including heli or snow catting,you may have witnessed the guides digging a pit in to the snow pack to evaluate its stability. You may also have seen ski patrollers doing this, notably at Western ski areas. Evidence of surface hoar in the underlying layers is one of the things they are looking for. It is also cause for alarm as it generally represents a very weak layer at high risk of releasing. (Another feature they may note, with alarm, is a layer of “ball bearing” like snow similar to hail. It looks like very small marbles and is a hazard as the overlying snow pack could literally roll right off of the “ball bearings’ forming a slide).

At any rate, the fact that this crystallization is occurring in my garden is good news for me as it means the weather is cooler and ski season is upon us. Here’s to a good winter!