As a navigation tool, CalTopo offers a complex feature set that sometimes takes time to hone. With a little savvy, CalTopo’s hidden gems make backcountry skiing/riding trip planning more useful. Here are four specific features to dial in your ski and winter climbing plans.
I spend a lot of time on CalTopo. Like, more than anyone should. For me, it’s an invaluable tool to plan future skiing and climbing trips. The mobile app is slightly less polished than Gaia, but I love being able to make separate files for different mountain ranges; it’s hard to beat the organization features of CalTopo. I’ll even go as far as to make a separate map file for upcoming trips making visible only the elements applicable to the planned objectives. Sometimes, it makes sense to get granular with a tool like CalTopo. It is powerful. The “secret” features I’ll discuss in this article aren’t hidden by any means; they’re just features I find valuable that some maybe haven’t unearthed.
Feature 1: Sentinel Weekly Live Satellite Imagery Satellite
I love using the “Sentinel Weekly” satellite imagery to investigate late-season skiing conditions. The Sentinel satellite imagery isn’t the highest resolution, but it’s updated every few days, allowing you to gauge current conditions. You can use it to evaluate if there’s enough snow present to warrant a long walk with skis on your back, and also use it to nail down the exact point/ elevation where snow starts. The images below show The Blaze, a popular summer ski destination in SW Montana. CalTopo stores all the historical imagery back to 2017, which is great for comparing the current conditions of a ski line compared to when you skied it in, say, June of 2021. In the images below, the “Contours” layer is overlaid to add more definition.
Feature 2: Sun Exposure
For spring ski-mountaineering, sun is the name of the game. Nailing the timing to allow a line to soften up, but not warm up so much that stability is lost requires precise timing. A prime example is the Ford-Stettner Couloir on the Grand Teton. The upper portion is more of a bowl feature; everything funnels into the narrows below. The “Sun Exposure layer” on Caltopo is a fantastic tool to evaluate when a line starts seeing sun. You can select the month and adjust the time of day to visualize how sun exposure changes throughout the day. It also serves as an essential tool to highlight how different parts of a ski line receive vastly different amounts of sunlight based on aspect. Below, you can see by 8:30 AM in April, the upper portions of the Ford Couloir and the Chevy Couloir on the Grand Teton receive sunlight, while the lower Ford Couloir and the Stettner are shaded. (The often used ascent route to ski the Grand ascends, in order, the Stettner, Chevy, and then Ford couloirs.)

On the upper flanks of the Grand Teton, in the wide open portion of the funnel. Photo: Austin Mallet.
It’s easy to get lulled into a false sense of security when you’re shivering in the shade low on a line, but there could still be considerable overhead hazards from the slopes above heating up. I also used this tool to plan my trip to the Ruth Gorge in Alaska this spring to select a location for a base camp that would receive the maximum amount of evening sun. The opportunities are endless.
In the images below, yellow=direct sun, blue=shaded.

The Ruth Gorge equivalent of the beach: A+ views and sunshine— CalTopo helped find both. Photo: Austin Mallet.
Feature 3: Viewshed Layer
Whenever possible, it’s always advantageous to put eyes on a ski line before committing to the approach. Even better is scoping out a line from the comfort of your vehicle, assisted by binoculars or a spotting scope. To determine what sections of the road a ski line is visible from, first right-click on a point centrally located on the ski line and select “Viewshed Layer.” From here, you can name the layer and select the eye altitude. If planning on scoping the line out from the ground, select 2m for the eye altitude. If you plan to climb a tree to get a better vantage point, select the tree’s height. Once created, the layer appears in two places: “Terrain Modeling” on the left menu and “Custom Layers” on the right menu. You can also change the color of this layer to optimize visibility.

In this viewshed layered map (The Great One), the purple shaded area denotes the terrain visible from a specified (altitude adjusted) point.
Feature 4: Export KML* Network Link to Google Earth
Google Earth can be extremely valuable for sensing specific terrain from behind the computer screen. Caltopo has a handy feature to export a “KML Network Link” to Google Earth which automatically updates the Google Earth application with any changes you make to your Caltopo file. Note: this only works on the Google Earth desktop application, not the browser-based or mobile device software.
The Google Earth satellite imagery isn’t quite as detailed as the “Global Imagery” layer. Still, viewing terrain in three dimensions helps immensely with spatial awareness when scoping out ski lines or approach tracks.
If you have a CalTopo Pro Account (which I highly recommend), you can also view Caltopo layers in Google Earth. CalTopo refers to these as “Super Overlays,” and I agree with the term. The layer I view most often is slope angle shading, but many other layers are available. Again, it’s hard to beat three-dimensional maps when trying to comprehend complex terrain from behind a computer screen.
(CalTopo does not feature 3D maps, something I know skiers/climbers frequently view on tools such as FatMap, onX, and Gaia’s web-based platform.)
*KML is a specific file format for displaying geographic data.
In the images below, we see three renditions of Whitetail’s North Couloir: Which below looks more the like real thing, CalTopo, Google Earth’s 3D,
or Google Earth with Slope Angle Shading? In any event, the line is steeper than it looks.
Behold the digital tools at our fingertips. With many options out there, find what works for you, and try to implement it into the planning phase of a single day or multi-day tour. Onward.

In the end, it’s about the turns. CalTopo and Google Earth helped plan the excursion, yet Mother Nature and some lung busting did the rest: a fine descent of Whitetail’s North Couloir. Photo: Austin Mallet.
Austin Mallet is originally from the flatlands of Houston, TX. Once the career opportunity presented itself, he moved to Bozeman, MT and never looked back. It didn’t take long to fall in love with the mountains and all the activities they have to offer. While living in Texas, Austin raced road bikes so it was an easy transition into the spandex clad world of skimo racing. These days, Austin is most passionate about climbing (specifically in the alpine) and ski mountaineering with a little trail running mixed in for good measure.
6 comments
These are great and well described tips.
For the weekly satellite imagery, I greatly prefer using the Sentinel Hub EO browser platform as you can view the same imagery in 3D, similar to google earth, for free. Narrow patches of snow and snow lines are much easier to make out when you can adjust the view angle.
Also, you should check out Apple Maps as their 3D satellite imagery is surpassing google earth in a handful of places. While that platform lacks mapping capabilities, the resolution of places with Flyover data is ridiculously good. For example, in the maps application for Mac or iOS devices you can see ski tracks going through the Bloody Couloir outside of Mammoth, CA. Plus Apple has steadily been adding more and more national parks. No Grand Teton yet but it probably won’t be much longer.
This kind of high profile display of local ski objectives is problematic and frustrating. Naming ski objectives in this article adds no value to the content. It serves only to accelerate already increasing traffic on soon to be over crowded ski lines. Admittedly, this is a drop in the bucket that is already overflowing, but its also somewhat uncharacteristic from most content on wildsnow. Please consider adopting the ethic of word of mouth or hand transfer of information for named ski objectives and terrain. Rich, entertaining content can be authored and posted online with out enhancing problems with over crowding and underthinking associated with online spray.
Based on Austin’s detailed trip reports on his own blog that link to strava activities with GPS tracks, I hate to say you might be barking up the wrong tree on this one, Steve.
I’d be curious to know if wildsnow has editorial guidelines they follow when it comes to naming and showing maps of ski lines. I’d imagine if you can find it in a published guidebook, they probably have no problem showing it, but beyond that I’d hope they consider the impacts before posting. I agree, the names of what were skied don’t really have much relevance on how useful caltopo can be.
Blaster, that’s some pretty remarkable imagery apple has. Feels like flying a drone in some areas. Again, I always wonder the pro’s and con’s of having such high res imagery of mountains and how that impacts traffic in these areas. Then again, if the imagery happens to show it in a pretty meager state, then maybe it could reduce traffic…
Hi Morris and by default Steve. I’ll try to address this all here. First, I found Austin’s use of CalTopo super helpful. He is digging down into that digital behemoth. I also think how he uses CalTopo can make skiing safer for a knowledgeable group.
Editorial guidelines: I thoroughly search the information out there for a ski line when posting something like this.
The guidelines I used are as follows. What information can I find about any of these lines on the Internet? Every line noted was well documented in the digital world, while two lines are in professionally published ski guidebooks. The first mention (I could find) of the couloir (as a ski objective) not written up in a ski guidebook (but is in a climbing guidebook) is 2010. And a climber/skier I respect noted in his FB post about the line that “Even though half of Bozeman has probably skied the thing it’s still a classic …”
After doing that research and reading up on the lines (no need to read up on the Grand Teton, but I’ll get to that), I felt Austin’s use of CalTopo and the easy-to-find info about these lines warranted publication. I did not feel as if WildSnow was disclosing secrets. Along those lines, I included the ski line names as I thought it allowed the specific features Austin highlights in CalTopo to be fully fleshed out.
Reading up on Internet beta regarding the classic line on the Grand Teton will take a day. Yes, that ascent and descent route has noted issues regarding crowding and potential human-caused hazards. I found Austin’s use of sun-exposure quite good, and I thought he displayed how he attempts to make a line like that safer for him (and maybe others because he’s not tempting fate if things will get warmed up). The real world application, I thought, was helpful and, hopefully, beneficial as others can apply that specific feature elsewhere.
Steve, I do hear you loud and clear. And the intent of a published piece doesn’t often matter. The intent here is not to overcrowd or to reveal secret goods. That said, safety for folks out in the backcountry is perhaps the end game with anything we publish.
In terms of barking up any tree, I think that is tough when it comes to singling out any individual. In general, the Internet and the digital space are complex, and no single person, in my eyes, is spoiling the goods for others.
I think both of you, however, raise good points. Thanks for your thoughtful comments. Anyhow, these are the guidelines I used when editing and publishing.
Thanks for the detailed response. Very cool to hear your thought process. It sounds like we agree on almost all points so please don’t interpret the following as a rebuttal. Regarding barking and trees, personal blogs are a lot of work and in most cases the rewards diminish over time. Maybe this conversation can plant a seed. So…
I certainly agree that no secrets were divulged here and would still like to advocate that the practice seen here shouldn’t proliferate in general. Hopefully I can clarify my stance: In my view it would be a positive outcome to stigmatize internet posting of names and locations of ski terrain (with obvious exceptions for the most nationally famous locations), while welcoming pictures and stories (sans route details) to be posted. It seems like a good compromise allowing (promoting?) creative expression while enhancing communication, connection, and exploration.
I think its pretty clear to those of us that ski relatively unknown terrain that skiers tend to ski what they see, online and or from the highway and in general only if route information is readily available.
I am an advocate for map skills and searching out new terrain. I enjoy communicating recommendations about even the emptiest terrain, person to person, friend to friend and peer to peer. Someday there will be skin tracks and people everywhere with parties avoiding communication at the trailhead and racing to beat each other for first tracks. Delaying this eventual reality even for a few years while building a healthier community seems to be a valuable goal. I’m interested to hear if people agree.
The point of the article was to highlight Caltopo features, not list out beta for ski objectives. Describing how I have utilized the tools to plan out my own ski objectives adds value to the article in my opinion. Also, this article would be pretty bland and hard(er) to understand if I didn’t include screenshots to depict the tools I’m describing. I purposely chose extremely well known ski lines for my screenshots and examples in an effort to not raise undue awareness to obscure ski lines. I feel pretty confident that no Wildsnow reader is going to hear for the first time about skiing the Grand Teton from this article.