Safety Swiss Avalanche Centers will subdivide Danger Ratings

[Slim]

The Swiss Avalanche Centers will start adding a +, =, or - to the danger rating.
(In Europe, a number is always used, in combination with the verbal rating, ie 1 Low, 3 Considerable, etc).
So now, instead of just calling it 2 Moderate , it would be subdivided into 2-, 2= or 2+.

If you can read German, here is an interview with some very interesting information about how they will do it, and how they researched.

https://www.bergundsteigen.com/wp-content/uploads/2022/11/bergundsteigen-121-seite-64-68-neue-unterteilung-der-gefahrenstufen.pdf

 

[Mendieta]

Thanks for sharing, @Slim . I can't read German. But I wonder why they didn't simply add half steps, such as 2, 2+, 3, 3+ ... It would be perhaps simpler to grasp.

 

[Slim]

Thanks for sharing, @Slim . I can't read German. But I wonder why they didn't simply add half steps, such as 2, 2+, 3, 3+ ... It would be perhaps simpler to grasp.

Not sure about that. I can guess:
this way it’s subdivide into three equal parts:
2-: the low end of level 2
2= : smack dab in the middle of level 2
2+ : at the upper end of level 2

That does feel more natural to me than just 2 subdivisions.

 

[Wilhelmson]

I can usually figure out my kids’ report cards and they don’t even use the A= convention just a plain A, A-, A+ and so on.

 

[RachelV]

The -/=/+ seems inspired be climbing grades, though climbing doesn't explicitly use the = (same as reports cards, that's true .

 

[SBrown]

Does it have to do with populating a form? (ie, needs two characters)

 

[Swiss Toni]

The Swiss Institute for Snow and Avalanche Research (SLF) in Davos is responsible for issuing the avalanche bulletins for Switzerland. They have written an article in English on the subdivision of danger levels in the avalanche bulletin https://www.slf.ch/en/news/2022/11/subdivision-of-danger-levels-in-the-avalanche-bulletin.html

 

[Mendieta]

The Swiss Institute for Snow and Avalanche Research (SLF) in Davos is responsible for issuing the avalanche bulletins for Switzerland. They have written an article in English on the subdivision of danger levels in the avalanche bulletin https://www.slf.ch/en/news/2022/11/subdivision-of-danger-levels-in-the-avalanche-bulletin.html

Thanks! The article answers my question, explicitly: “A 3-minus remains a level 3 and indicates ‘considerable avalanche danger’ – it is not to be taken lightly or treated as though it were a 2.”

They really want more granularity, particularly around level 3, which expanded a significant range of risk in practical terms. They recommend staying away from 3+ and higher. So, a user might decide to go to a 3- region instead of a 3+. Also, the 2D color map of risk rating vs height is super educational IMHO. Great read.

 

[jmeb]

Very interesting -- thanks for posting. It's always interesting to see how different avalanche centers slice up their problems. In Colorado we see many folks regularly using the term "scary" / "spooky" moderate -- which seems like 2+ would help communicate. As always the research from SLF behind this change is very thoughtfully done and presented.

Lots of different ways how folks try to add precision to their forecasts. For a few years, the Swiss have used dynamic zones in their products. Just this season Avalanche Canada and Colorado added dynamic zones to their products. Swiss only put out one danger rating compared to the three typical in North America. Some centers put out aspect/elevation for each avalanche problem, some highlight the primary aspect-elevations in which you will find the problems. Some of this seems driven by geographic areas they represent (i.e. mostly alpine terrain vs lots of near- and below-treeline, multi-day remote trips vs more accessibility) -- some by different communication theories or data to support particular forecasts.

 

[slow-line-fast]

the 2D color map of risk rating vs height is super educational IMHO. Great read.

If you mean the graphic in the SLF news article linked above, that is slope angle on the y axis, not height. It's called the graphical reduction method, explained here in English:

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In continental snowpacks like Colorado, I'd take a fair few cautious steps back from the indicated danger zones, which is developed for and used in the Alps. Basically shift the danger zones down and to the left, because the snowpack typically has so many deep weak layers, compared with the Alps.