How to read the Avalanche Advisory

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The Eastern Sierra Avalanche Center issues a slightly modified version of avalanche advisories than most centers typically publish. The primary difference between our model and others is that our advisory does not include a Hazard Rating or Stability Rose - but it does include all the other core aspects of typical advisories. This is largely due to the fact that we do not issue advisories seven days a week, and do not want to leave Hazard Ratings up for periods longer than 24 hours.

The information below describes how our advisory is structured, and how to interpret it.
 

The Bottom Line
The Bottom Line highlights the key points of the avalanche advisory, in a summary format. While this information should not be taken without reviewing the rest of the advisory, it does provide the salient points up front.

Avalanche Problems

 

Below the Bottom Line section, you will find the avalanche problems for the day.  These have a series of symbols and graphics above a description to help explain the avalanche problem and help you remember it while making decisions in the field.

Avalanche Character

There are many different kinds of avalanches and each has its own characteristics.   Most Level 1 avalanche classes cover these various avalanche problems.  For a quick tutorial, click HERE.

For each problem, we tell you both graphically and in text, where you will find the problem by aspect and elevation, the characteristics of the problem including how easy it is to trigger, its size and distribution, and whether or not its is becoming more or less dangerous.

The Aspect-Elevation Rose

The aspect-elevation rose is a powerful way to understand the general avalanche pattern in a glance by aspect (the direction a slope faces) and elevation.  

These blue-and-grey roses are what we call "locator roses" meaning that they show you the general aspect and elevation where you will MOST LIKELY find the avalanche problem, not all the places where you might find it. The blue areas indicate where this avalanche problem likely exists and the grey areas indicate where it likely is absent.

Likelihood of Triggering means the probability that a single person will trigger that type of avalanche in the terrain specified. 

Size means the size of the avalanche.  Small avalanches are D1 in size or not quite large enough to bury a person unless other factors like terrain traps contribute to magnify the consequences of the avalanche. Large avalanches are D2 avalanches meaning that they can bury or injury people. Very large avalanches are D3 avalanches that can bury and destroy a car, damage a truck, destroy a small building or break a few trees. Historic avalanches are D4 and D5 avalanches that can destroy a railway car, large truck, several buildings, a small village, or a forest area up to 40 hectares. 

Following the Avalanche Problems section, there is the Advisory Discussion section which talks about the overall recent snowpack history and avalanche concerns more generally.  Following that is the Recent Observations section, which provides links to and descriptions of recent specific field observations.  Following that is the Weather section which provides pertinent weather forecast information.  Then there is the Two-Day Mountain Weather Forecast data section, which provides this information in a simple table format. 

Finally, remember this information is only for AVALANCHE TERRAIN, which is generally slopes steeper than 30 degrees (or flatter slopes locally connected to steeper terrain).  Even on high danger days you can find much safer terrain if you stay on slopes less steep than about 30 degrees that are not underneath steeper terrain.

 

 

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