How to read avalanche bulletins

I have known too many people who have been involved in avalanche accidents and incidents. What stands out in all these events is the fact that all the info was there in black and white in the avalanche bulletin – but people either failed to notice it, or failed to heed the fact that it really meant it!

Here’s a short guide to learning more about how these bulletins are written, and what the forecasters really mean.

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THERE IS A PERSON BEHIND THOSE WORDS

Avalanche forecasters are not some suited geeks sat at a big computer with a lack of interest in skiing – far from it. These guys and girls are out in all weather, gathering data and making crucial observations.

They have a wealth of experience, a passion for their subject and, just like you, they spend a lot of time looking for the best snow. The difference is they are obsessed with how well it is all stuck together. If you read an avalanche bulletin like it was written by a psyched and caring uncle (rather than the headmistress) then you’ll be on the right track from the start.

SO WHAT’S TO KNOW?

The avalanche forecasters will be out and about gathering information about the weather conditions (did the forecast come true? What are the atmospheric conditions?). There is a lot of poking around in the snow. They’ll be skiing up high and down low to see how the conditions change with altitude; they will be furkling in the snow to find out how sticky, powdery and consolidated it is, how many dodgy layers there are, and how well it’s all stuck in place.

They’ll be skiing from one side of the hill to the other to see how the slope aspect impacts the snow; and they will be taking particular interest in ridge lines and wind-affected areas to look for accumulations of wind-slab, and to find out how well-bonded these dodgy rafts of snow are. All the time they will be scouring the hillsides for evidence of avalanche activity.

SO WHAT HAPPENS WITH ALL THIS INFO?

This is where the geeks come in. The whole lot – atmospheric conditions, snowpack information and avalanche evidence – is fed into a super computer. It whirrs away and comes up with a fantastically-detailed model of the day, which is logged alongside thousands of others. But working out how things are now is of little use when you want a forecast for tomorrow – so here’s where the magic happens.

The weather forecast for the next 24 hours is added and the machine goes giddy as it whirrs its way through the last few decades to find the perfect match; it will find examples of days in the past when the snow and weather conditions were almost exactly the same as they are forecast to be tomorrow – et voila! All they have to do is look at the avalanche activity on those closely-matched days, and you have a pretty good idea of what to expect.

ALL SOUNDS PRETTY SCIENTIFIC, SO WHAT COULD GO WRONG?

Here is the first (and most important) lesson of the day: it is all based on the weather forecast. All that collected data was irrefutable, but then we threw a weather forecast into the mix. And the weather doesn’t always play ball. This is a chink in the armour of the avalanche bulletin – and one of the most common factors in avalanche accidents. So, if the weather forecast was wrong, then don’t expect the avalanche conditions to remain the same as the forecast.

SO WHAT DOES THE AVALANCHE FORECAST FORECAST?

The problem with loads of us skiers is that we’re in a rush to go skiing. So we often don’t look past the number. We all know that it’s a scale of 1-5 right, so three is kind of average, four is worse, and two is loads better right? WRONG (in a big way). This is a scale of hazard – so zero would mean that there is no risk of avalanche and it gets worse from there. On a category-three day it is almost certain that there’ll be avalanche activity.

The key is in making sure you know where and when – and don’t get caught with your pants down, so to speak!

Worse than that is when a low number coincides with a dodgy forecast. Important lesson number two is this: I have known several people get nailed by a spontaneous avalanche (and a big one at that) on a category-two day. “That shouldn’t happen,” ?I hear you say! Having had a good look at the wording of the European Avalanche Scale you’d be right, but the weather changed and the number two was just a figment of the computer’s imagination. The avi was real.

THE DEVIL IS IN THE DETAIL

This is where you can heed advice from a real person (remember those passionate mates of ours?), so pay attention. If you read an avalanche bulletin with care you’ll find they tell you exactly where, when and how it could go wrong – and even what to look for.

I remember an accident where the bulletin had talked about ‘deep instabilities’. Leaving the hut early, the team tested the surface, poked the snow throughout the day, took note of their tracks and the lack of slab.

Unfortunately they missed the point. If they had read the words they would know that the risk came from deep layers, and just as all their tests indicated the conditions were okay, a massive and deep avalanche proved they weren’t.

FINALLY, READ THE SMALL PRINT

There is no such thing as stock phrases and wasted words. These forecasters know that they have a huge amount of crucial information to convey – and not many words to use. So each one is critical. Put yourself in the mind of the writer. What might he/she be getting at?

A great example was looking back at an avalanche event to find the words “Heed the daytime danger cycle!” at the foot of the bulletin. At the time it seemed like a passing comment. But why would the you write that? Why was it so important that it had an exclamation mark on the end? Furthermore, it didn’t appear on the day before, or the day after the avalanche – only the day when the accident happened.

 

Fall-Line Skiing Magazine
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