We rebuilt the Zones tab. Here's why it failed, what we replaced it with, and how the scoring works.
When I built the Zones tab, I had an ambitious idea: Snow Doctor would be a living library of documented terrain zones across BC. Each region would have a curated set of ski lines, complete with photos, approach notes, elevation, aspect, and ATES ratings. Think of it as a crowd-sourced, admin-managed guidebook baked right into the forecast tool.
It was a great idea on paper. In practice, it was never going to work. Building and maintaining that kind of database across BC is a full-time job. I'm one person who also skis. And frankly, there are people who know their regions far better than I ever could. The Jim Baldwins and Matt Gunns of the backcountry world. If that library ever gets built, it won't be by me alone.
So I killed it. Or rather, I rebuilt it into something that actually solves the problem I started with.
Here's the scenario I keep coming back to: it's Thursday night. You've decided you want to ski somewhere in Kootenay Pass (or Whistler, or Rogers Pass, wherever your zone is) this Saturday. You've got four or five spots you know and love in that area. The avalanche forecast just dropped. The weather is showing partly cloudy with 10cm Friday night.
Which spot do you go to?
Right now, you're doing that math in your head. You know Spot A is alpine-facing NW, high consequence, amazing on a bluebird but sketchy in flat light. Spot B is a treeline mellow zone that works in almost any conditions. Spot C is your deep-powder spot but only when there's actual fresh snow.
You're manually cross-referencing your mental map of spots against a forecast that doesn't know your spots exist. That gap is exactly what the new Zones tab is built to close.
When you open the Zones tab for a region, you now see a personal conditions dashboard: a scored, ranked list of your saved stashes in that area, assessed against the current forecast.
Each stash gets a score. The score is a single number that accounts for three things: the terrain itself, the weather, and the avalanche forecast. Here's how each part works.
Not all terrain is equal, and the algorithm acknowledges that. Alpine lines get a bonus for being high-value objectives. Complex ATES terrain gets a small reward for the commitment it demands. This isn't a safety rating; it's an acknowledgement that some spots are worth more when conditions are right.
| Factor | Score |
|---|---|
| Alpine elevation band | +2 |
| Treeline elevation band | +1 |
| Below treeline | 0 |
| Complex ATES terrain | +1 |
| Challenging ATES terrain | +0.5 |
| Simple ATES terrain | 0 |
Weather is where the score gets interesting, and elevation-aware. The same forecast can mean very different things depending on where your stash sits. A rainy forecast at 800m doesn't mean rain at 2000m; the algorithm uses the freezing level from the weather data to check whether precipitation is hitting your stash as rain or snow.
| Condition | Score |
|---|---|
| Bluebird (≤15% cloud), Alpine | +3 |
| Bluebird (≤15% cloud), Treeline | +1 |
| Greybird (50–80% cloud), Alpine flat light | −1 |
| Socked in (≥80% cloud), Alpine | −3 |
| Socked in (≥80% cloud), Treeline | −1 |
| Snowy (3–15cm SWE) | +1 |
| Very snowy (≥15cm SWE) | +2 |
| Rainy at elevation (freezing level above stash) | −3 |
| Very rainy at elevation | −5 |
| Windy (≥15 km/h), Alpine or Treeline | −2 |
| Very windy (≥30 km/h), Alpine or Treeline | −3 |
| Warm temps (>0°C at elevation) | −2 |
| Warm temps, Solar aspect (S, SE, SW) | −4 |
This is where the scoring gets serious. We pull the Avalanche Canada danger ratings for each elevation band and apply penalties that scale with the danger level. A Considerable rating drops your score. A High rating tanks it. An Extreme rating is a hard −12.
But we go deeper than just the danger rating. We check each active avalanche problem against your stash's specific elevation band and aspect. If you've saved a north-facing alpine run and the forecast has a Wind Slab problem rated "Likely" on north-facing alpine terrain, that stash gets hit hard.
| Factor | Score |
|---|---|
| Danger rating: Low | 0 |
| Danger rating: Moderate | −1 |
| Danger rating: Considerable | −3 |
| Danger rating: High | −6 |
| Danger rating: Extreme | −12 |
| Avalanche problem, elevation band match | −1 |
| Avalanche problem, aspect match | −1 |
| Likelihood: Likely | −2 |
| Likelihood: Very Likely | −3 |
| Likelihood: Certain | −4 |
| Size penalty (per size unit, e.g. Size 2.5) | −2.5 |
The final score is a sum of all the above. Here's how the labels map to score ranges:
| Score | Label |
|---|---|
| 7 or above | Great Day |
| 4 to 6.9 | Good Conditions |
| 1 to 3.9 | Worth Checking |
| −2 to 0.9 | Marginal |
| −5 to −2.1 | Tough Day |
| Below −5 | Avoid |
The score is displayed as a circular fill indicator next to each stash; the ring fills from empty (worst) to full (best) and changes colour along the spectrum. Tap any row to open a full breakdown showing exactly which factors contributed and by how much.
Alongside the scored profiles list, there's a Risk Heatmap view. It shows your stashes placed on a grid with ATES rating on one axis and avalanche danger rating (at that stash's elevation band) on the other. The cell colours reflect the general risk alignment of each combination, so you can quickly see if any of your spots are sitting in an orange or red cell for today's forecast.
This scoring system is not a substitute for your judgment. It doesn't know about your group's skills, the snowpack history, or the specific features of each line. It's a decision-support tool, not a decision-making tool. The forecast it uses is the same one you're already reading on Avalanche Canada; we're just connecting it to your personal terrain in a way that saves you the mental effort of doing it manually.
A high score doesn't mean a spot is safe. A low score doesn't mean a spot is dangerous. The algorithm is opinionated, and those opinions will evolve as we get feedback on where the scores feel off.
The conditions dashboard only works if you've saved zones for the region. Sign in, head to My Zones, and add your favourite lines. You don't need 30 spots; four or five well-chosen runs in a region you ski regularly will give you meaningful comparisons.
Tag each zone with the right aspect, elevation band, and ATES rating. Then the next time you're planning a trip, the Zones tab does the rest.
Snow Doctor started as a way to put Avalanche Canada's forecast data in a more usable format. It grew into a tool for saving and organizing terrain. The Zones tab is the piece that connects those two things: your terrain, your conditions, your call.
If you've been using the app mainly for the forecast tabs, I hope this gives you a reason to spend five minutes building your stash library. Once you do, the forecast stops being abstract and starts being personal.
Go ski good snow.
— Matias
Snow Doctor is a free tool. If it helps you make better decisions in the mountains, consider sharing it with your crew. And if the scores feel wrong on a particular day, let me know. The algorithm is easy to tune.