Reading the Avalanche Forecast
Before reading this post, it is important that you know the different kinds of avalanches. Check out our blog that goes over this here: How to Quickly Identify the Different Kinds of Avalanches
Now that you know the different kinds of avalanches, the avalanche forecast will make a lot more sense to you!
What is the avalanche forecast?
The avalanche forecast is an incredibly useful tool for backcountry skiers, snowshoers, and snowmobilers. It is usually put together by your local avalanche center who send out a professional each morning to analyze the snow pack. They then put this information into an easy to read page found on their website or app for us backcountry skiers to use in order make our safety decisions each day. Check out how the Utah Avalanche Center creates their forecast:
What does the avalanche forecast tell you?
The avalanche forecast is saturated with important information. Here is a list of what each days report will tell you:
- How likely it is that an avalanche will occur
- What kind of avalanches may occur
- How big that potential avalanche will be
- What aspect the avalanches will most likely happen on
- The elevations these avalanches are possible at
- Current weather
- Future weather forecast
- Observations of different areas by other skiers
Avalanche Danger Scale
The avalanche danger scale is color coordinated making it easy to read. The colors are pretty self explanatory but it is best to know them and what they mean.
- Green – Low avalanche danger, if triggered the slide will be small, natural avalanches not likely
- Yellow – Moderate avalanche danger, avalanches possible on certain aspects, natural avalanches not likely
- Orange – Considerable avalanche danger, small avalanches likely and large avalanches possible
- Red – High Avalanche Danger, large avalanches likely with very large possible on certain aspects
- Black – Extreme avalanche Danger, large and very large avalanches certain
The Aspect Elevation Rose
This is the graph that will tell you the likelihood, aspect, and elevation avalanches are most likely to occur on that particular day.
Now, let’s identify what the layers and overall shape of the rose is. It’s a octagonal shape and has 3 sections to it: a center, middle, and outer section all the way around. Think of it as a target you would shoot with a bow and arrow, or simply take a look at the example picture to the right.
The part that can be a little bit hard to grasp is you have to think of this rose as if you are looking down directly onto a mountain peak. The center portion of the rose represents above tree line, the middle portion represents at tree line, and the outer portion represents below tree line. This is what allows the rose to tell you what elevation the avalanches are likely to occur.
Since we now know the elevation part of the aspect elevation rose, what tells us which aspects are susceptible to avalanches being triggered? Well, if you look at the picture of the rose to the right, you will see that there are 8 triangles that make up this octagon. Each triangle is a different aspect on the mountain and is usually labeled. In this one (and most others) the very top is north and you go around from there counting off NE, E, SE, S, SW, W, and NW in a clockwise fashion.
Once you understand the concept, it is fairly easy to figure out how to read these. Some roses will have color and some will be black and white. The ones with color give you the severity of the avalanche danger that exists in the backcountry for that specific day. For now, let’s use the rose above as an example.
You wake up in the morning to a couple inches of snow on the ground at your house, but you know that means there is almost double that in the mountains, so you decide to head out into the backcountry. Like a responsible, safe skier, you check the avalanche forecast before leaving the house and you see the rose above. Well since the middle and inner portions of the rose are shaded in on the NW, N, NE, E, and SE aspects, you know that these aspects at and above tree line are where there is possible avalanche triggering.
While those are the main graphs and visual representations of what the avalanche professional found that morning, there are parts of the forecast that tell you what kinds of avalanches are most likely, what the weather as been along with a future forecast, and observations from other people that have skied different zones that this forecast covers.
Personally, I stay out of the backcountry completely if the avalanche danger is high or extreme. If it is considerable, being cautious is extremely important and strategic route choice is essential. Stay tuned for a post on choosing the best routes in the backcountry!
If you are looking to sign up for a professional avalanche class, check out these resources where you can find one near you:
- AIARE Course Providers: https://aiare.info/providers_list.php
- Upcoming Public Avalanche Training Courses: https://aiare.info/course_list.php
- Choosing an Avalanche Course: https://avtraining.org/choosing-an-avalanche-course/
For more avalanche education, check out the rest of our articles: