An avalanche list that only takes points away, and a weather score you set yourself. Never added together.
Save the spots you actually ride, each with its elevation band, aspect and terrain class, and My Zones reads every one of them against the forecast. You know Spot A faces northwest in the alpine and is committing. Spot B is a mellow treeline lap that works in most weather. Spot C is only worth it after fresh snow. My Zones does the cross-referencing you'd otherwise do in your head the night before.
When people look at a list of their spots, they ask two different questions. How much is stacked against this slope today? And how good will the skiing be?
The first version of My Zones answered both with one number. That meant adding them up, and adding them up let a bluebird powder day pay off real avalanche concerns. We patched it with a cap, but the honest fix was to stop adding. So each zone now gets two answers that never touch:
Avalanche
What counts against the zone today. It starts at 0 and only goes down. 0 means nothing on the list applies. It never means safe.
Weather
How good the skiing might be, by your own values. It starts at 0 and goes up or down.
In both, higher is better. Snow Doctor never weighs one against the other, never sorts by both at once, and never tells you to go. If you weigh good snow against what's stacked against a slope, that's your call to make, with your crew, on the day.
Every item on the list takes one or more points off. There are two halves: what this day brings, which changes with the forecast, and what the slope is like, which doesn't.
| Item | Points |
|---|---|
| Danger rating at the zone's band: Considerable | −1 |
| Danger rating at the zone's band: High | −2 |
| Danger rating at the zone's band: Extreme | −3 |
| Each avalanche problem listed on the zone's band and aspect | −1 |
Danger counts more as it climbs because High is a different day from Considerable, not one notch worse. Low and Moderate count nothing: the list is there to separate your zones on the days that need it. These are the defaults: in your profile you can make any rating count for more, down to −10, but never less.
Problems have to match both the band and the aspect. A wind slab listed on north through east alpine slopes is describing a place on the mountain. A south-facing alpine run isn't in it, and neither is a north-facing run below treeline. Every problem that matches counts, so two problems on the same slope count twice. A persistent slab counts the same as any other: the rating already says how serious the day is.
Tomorrow and the day after use the danger ratings the bulletin gives for those days, and today's problems for all three. Assuming today's problems carry forward is the cautious reading. If a problem drops off tomorrow, it drops off the list tomorrow.
Under the list, two weather signs answer yes or no. They take nothing off. Forecasters already weigh new loading and warming when they set the rating and list the problems, so a point for either would count the same thing twice. They're there so you can see what the weather has been doing at your zone's height.
Says yes when the 48 hours to the end of the day bring 30 cm of new snow or 5 mm of rain at the zone's height, or wind of 40 km/h or more while there's 10 cm or more of new snow from the last three days to move around. The wind is read high, at the level of the ridgetops, because that's where slabs are built.
Says yes when the day's high at the zone's height reaches 0°C or more, and is at least 5° warmer than the coldest high of the three days before. A spell that has been mild for days doesn't count. The point is the change.
We ran every version of each rule we could think of over a whole winter: December 1 to April 15, 2025-26, on 39 saved zones across eight regions, using Avalanche Canada's archived bulletins and the same weather model the app uses. For each version we asked one question. On the days it fired, how often had the forecasters listed the matching kind of problem on that zone's band?
| Rule | Fired on | Forecasters agreed | On any day |
|---|---|---|---|
| Loading, against storm or wind slabs listed on the band | 34% of days | 92% | 74% |
| Rapid warming, against wet loose or wet slabs listed on the band | 7% of days | 70% | 23% |
"On any day" is how often forecasters listed that kind of problem at all, so it's what a rule that always fired would score. Both rules beat it, warming by three times. We picked the versions that agreed most often, because a yes should mean something. That agreement is also why they don't count: on the days loading said yes, the forecasters had nearly always said so already. Reading the wind lower down, at 80 metres instead of ridgetop height, added nothing over snow and rain alone. The full comparison, and what else last winter showed, is in A Winter of Forecasts on 39 BC Slopes.
| Your answer | Points |
|---|---|
| Steepness under 30° | 0 |
| Steepness 30 to 35° | −1 |
| Steepness over 35° | −2 |
| Terrain traps: gullies, trees, cliffs or anything that makes getting caught worse | −1 |
| Can produce an avalanche of size 2 or bigger | −1 |
| Complex terrain (ATES) | −1 |
| Extreme terrain (ATES) | −2 |
The terrain classes are defaults too. Simple and challenging count nothing unless you make them count in your profile, and complex and extreme can count for more, down to −10.
A blank answer counts nothing, and in a list of numbers nothing looks a lot like fine. So any zone with a blank slope answer gets a dashed edge on its pin and its chips, and the list shows the question as a "?". The real number could be lower. "No" is an answer, not a blank. The same goes for the zone's band and aspect: without them, the danger rating and the problems can't count. And for a day with no danger rating, early or late in the season, when the bulletin has no number for the danger and problems lines to count.
Recent avalanches, shooting cracks and whumpfing. Those are seen on the snow, and Snow Doctor only hears about some of them. They aren't on the list, and they're exactly the things to look for when you get there.
This is the half that's about you. A storm skier and a bluebird chaser want opposite things from the same forecast, so every value below is yours to change in your profile. The survey picks a starting set from one question: storm days, clear days or whatever skis best.
| Item | When | Default |
|---|---|---|
| Bluebird | 15% cloud or less in daylight | +3 |
| Flat light | 50 to 80% cloud | −1 |
| Socked in | 80% cloud or more | −3 |
| Snowing / snowing hard | more than 3 cm / 15 cm that day | +2 / +3.5 |
| Recent powder | 10 cm or more in the three days before | +2 |
| Stayed cold since | the freezing level stayed below the zone since it fell | +1.5 |
| Wind on the new snow | recent powder, and wind of 30 km/h or more that day or the day before (50 at ridgetop height) | −1 |
| Windy / very windy | 15 / 30 km/h, or 40 / 60 at ridgetop height, where 30 km/h is an ordinary day | −1 / −2 |
| Rain / heavy rain at its height | more than 5 / 15 mm with the freezing level above the zone | −3 / −5 |
| Above freezing | a high above 0°C, doubled on a southeast to southwest aspect | −1 |
Trees cut the wind and give you contrast in cloud. So the sky and the wind cost less lower down: half at treeline, and below treeline the sky costs nothing and the wind a quarter. On a windy grey day, a treeline zone comes out ahead of an alpine one for that reason. It's shelter, not a preference for trees.
| Item | Storm days | Clear days | Whatever skis best |
|---|---|---|---|
| Bluebird | +1 | +5 | +3 |
| Flat light | 0 | −2 | −1 |
| Socked in | −1 | −5 | −3 |
| Snowing / hard | +3 / +5 | +1 / +2 | +2 / +3.5 |
| Recent powder | +2 | +3 | +2 |
| Stayed cold since | +1.5 | +2 | +1.5 |
Apart from making the danger and terrain-class points stricter, nothing in your profile touches the avalanche list.
Before settling on any of these numbers, we ran every rule over a whole winter: December 1 to April 15, 2025-26, on 39 saved zones from the North Shore to Rogers Pass. Here's how their pins would have looked on the default values. The slope questions were blank on every one of those zones, so the avalanche colours are a little lighter than a fully described zone would show.
A pin was near-white or pale (0 or -1) on 41% of days and deep red (-5 or lower) on 3%. Height made the biggest difference: alpine zones were pale on 27% of days, treeline on 54% and below treeline on 91%. December and March carried the most.
The weather pin was light blue or better on 56% of days, blue (+3 or more) on 15%, and grey on only 12%. An ordinary BC winter day lands on light blue, because it's a good day. Treeline did best (69% light blue or better), sheltered from the wind and with contrast in the trees; the alpine was light blue or better on 48% of days.
One row per zone, one column per day. Grey columns are days without a danger rating.
Avalanche
Weather
Read across a row and you see one slope's winter: storm cycles turning the avalanche pins red in early December and mid-March, quieter stretches in January and February, and the weather pins brightening on the clear days between storms. Read down a column and you see one day across your zones, which is what the map shows you. What else that winter showed, from height to wind to how the weekends went, is in A Winter of Forecasts on 39 BC Slopes.
The Layers button holds every choice of what the map shows. Colour the regions by avalanche danger, new snow or freezing level. Show your zones by their avalanche list or their weather score. Both are on at once, so you can see the bulletin's danger and your own zones together. Pick today, tomorrow or the day after, and the danger colours and your zones move together. The Legend button explains the colours when you want it, and stays out of the way when you don't.
Tap a pin and the zone's report opens on This zone: the three-day table, the list for the day you pick, and the terrain and danger grid. The bulletin, At a glance, and the zone's own weather table and charts are one tap away, unchanged.
Inside a zone's avalanche list there's a grid you can open: terrain class on one axis, the day's danger rating on the other, drawn from Avalanche Canada's published terrain and danger matrix, with your zone placed in it. It's reference, and it doesn't feed the list.
It isn't a verdict. 0 on the avalanche list doesn't mean safe, and a high weather score doesn't mean go. Neither knows your group, your experience, the snowpack's history or how you'll get to the slope. If reaching a mellow north-facing treeline run means crossing a loaded south-facing path higher up, that exposure isn't anywhere in either number.
It's a way to read your own terrain against the forecast without doing it all in your head, and to see why, item by item. The bulletin it reads is the same one you already read on Avalanche Canada.
Sign in, head to My Zones, and save the lines you ride. Four or five in a region you know are enough to compare. Give each one its band, aspect and terrain class, and answer the slope questions while you're there. Those answers are what separate two zones on the same band on the same day.
Go ride good snow.