Aspect Filtering on Ski Touring Routes

Posted on Mar 31, 2021
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Posted on Mar 31, 2021
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NEW FEATURE | We've added the ability to filter ski touring routes by main aspect. This should make it easier for planning ski touring trips, using this aspect information in conjunction with local avalanche advisory bulletins, weather observations, and route planning. To each post, we've added a 'Main Aspect' and 'Secondary/other aspects'. Do let us know if this feature is helpful, and if we can improve it in any way.

WHAT IS ASPECT?
Which direction a snowy slope is facing is referred to as ‘aspect’. Knowing what aspect a slope is – North, East, South, West – is important for making informed decisions regarding the likely snow and stability conditions on the slope. That is, as one information point, aspect helps experienced backcountry travelers to make inferences about avalanche risk and ski conditions. Most avalanche advisory communications will include information related to slope aspect at different elevations.

The aspect data is also a convenient way of guessing how amazing the snow might or might not be for skiing – north is colder, south is warmer. Wind from certain directions can strip some slopes bare. Especially in spring, this information is handy – a northern slope might be icy and crusty, whereas a southern slope might be nice corn.

In this way, aspect is used for multiple inferences as backcountry skiers plan their trips into the mountains.

For each and every ski touring route, we’ve made a note of the MAIN ASPECT and any SECONDARY/OTHER ASPECTS.

MAIN ASPECT
What we call the Main Aspect is the aspect we’ve identified as being the most consequential exposure for backcountry travelers on any given route.

We’ve provided this information as one reference point among many, for experienced backcountry travelers to make their own decisions regarding avalanche hazards and risk, as well as overall snow conditions for skiing.

In reality, many of the ski touring routes on Hokkaido Wilds don’t even venture into high risk avalanche terrain. Most routes are the most conservative options for getting to a peak – via ridges and low-angle slopes. But hopefully, being able to filter routes based on any given day’s avalanche risk profile should make route selection and planning easier.

It’s important to understand that these ‘Primary Aspects’ only apply to slopes across which the described route crosses. There will always be a myriad slopes one could ski off any given route. In that case, the skier needs to take extra care in understanding that slope’s relationship with the weather and terrain.

OTHER ASPECTS
What we call the Secondary (or Other) Aspect is any other aspect that skiers may encounter – or can’t avoid – in order to complete a route.

For example, a route may follow a forestry road approach deep in a ravine or gully. It may traverse across a forested slope as skiers access the main objective. Given a high-risk avalanche bulletin cautioning against travel on or below southeastern slopes, one might shy away from some routes that include this exposure. 

For some long traverse routes, there may be a number of aspects encountered. The notable ones are noted with this feature.

WHERE TO FIND ASPECT NOTATION
Aspect notation is included on the Ski Tour overview page (https://hokkaidowilds.org/skitour) on the route ‘cards’ at the top right of each card, in the form of a cardinal direction letter in either a blue (main aspect) or grey (other aspect) box.

It’s also at the top right of the route statistics on each separate route page.

At present, it’s only possible to filter routes based on their Main Aspect, not on the other aspects associated with the route. We recommend using the filter to identify candidate routes and then using the topographical maps to undertake a more detailed analysis and plan of your likely route.

ASPECT BLURBS IN THE ROUTE POSTS
We’ve also added an automatically generated Aspect blurb on each ski touring route post, with extra information, links to pin-pointed weather, and links to local avalanche bulletins, if they exist for the area. We were excited to see the launch of the international standard JAN avalanche reports into Hokkaido for the 20/21 winter season and we look forward to this continuing, and hopefully expanding, in future years. 

USING THE AVALANCHE ‘ROSE’?
The international standard reporting adopted national and regional avalanche centers in Canada, USA, New Zealand, Europe and Japan (via the Japan Avalanche Network) will usually provide a list of ‘avalanche problems’ and an indication of the likely spatial distribution of this problem across different elevations and aspects. This is often presented in what is referred to as an Avalanche ‘Rose’.

So, for example, the image on the right shows a snip of the JAN report for the Niseko Yotei Yoichi Shiribeshi region in late March 2021. You can see that it describes a very common ‘spring’ avalanche problem; wet, lose avalanches. These tend to result from the rapid warming and melting of the snowpack due to ambient temperature. As such, we can see this problem is ‘likely’ to occur at elevations of ‘treeline’ and below and that it is ‘likely’ to occur on all aspects.

As a contrast, this snip to the left  is taken from a report in the same region of Hokkaido in mid-January of 2021. Here our avalanche problem is a ‘wind slab’. This problem tends to result from the transport, deposition and compression of fresh snow by the prevailing winds and therefore is usually localized to a specific slope aspect.

We can see that the report indicates that this problem is ‘possible’ to occur on northerly aspect slopes at elevations above tree line (‘alpine’).

By using the information from the avalanche report, our understanding of recent snowpack conditions and recent weather we are able to make informed decisions about terrain selection. As the ski-guide adage goes;

“If stability is the problem, terrain is the answer”

IS THIS A HELPFUL FEATURE FOR YOU?
We hope that the aspect information we’re providing for each route becomes a useful tool for trip planning. If you’ve got any comments or feedback about this feature, please let us know in the comments below.

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ADVANCED FILTERS

Filter by location

About Filters

REGION: The general mountain/geographical region the route is in.

BEST MONTH(S): Time of year a route is suited to visiting. Some pop all season, some are more limited.

DIFFICULTY: How strenuous a route is, and how technical it is. Full details here.

FREERIDE/SKITOUR: Very subjective, but is a route more-of-a-walk-than-a-ski or the other way around? Some routes are all about the screaming downhill (freeride), some are more about the hunt for a peak or nice forest (ski-tour). Some are in between. 

MAIN ASPECT: Which cardinal direction the primary consequential slope is facing, that you might encounter on the route. More details here.

ROUTE TAGS: An eclectic picking of other categories that routes might belong to.

SEARCH BY LOCATION: You can find routes near your current location – just click on the crosshairs (). You may need to give permission to HokkaidoWilds.org to know your GPS location (don’t worry, we won’t track you). Or, type in a destination, such as Niseko or Sapporo or Asahikawa etc.

Please let us know how we can make it easier to narrow down your search. Contact Rob at [email protected] with your suggestions.

Aspect Filtering on Ski Touring Routes Difficulty Rating

Category

Grade

Points

Strenuousness

Vertical Gain

D

25

Time ascending

D

0

Technicality

Altitude

D

0

Hazards

D

0

Navigation

D

0

Totals

25/100

GRADES range from A (very difficult) to D (easy). Hazards include exposure to avalanche and fall risk. More details here. Rating rubric adapted from Hokkaido Yukiyama Guidebook 北海道雪山ガイド.