How to Tell If There Is Snow On the Trail

In This Guide Using SNODAS Snow Depth Map Overlays

Understanding Snow & Mountain Weather

Overlaying Recent Satellite Photos on the Map

How to Check For Avalanche Risk

Sources for Local Trail Conditions

Every winter, I get a ton of emails asking me if there’s snow on the trails that I create guides for. The answer is that I usually don’t know the conditions unless I’ve been there recently, and unless you go there yourself, it’s impossible to know the conditions for certain. But there are some high and low tech ways to make an educated guess about the snow and trail conditions that I use all the time. It’s not perfect, but generally, it will give you a good idea of whether you’ll encounter snow on the trail for your hike.

Even experienced hikers die hiking in winter conditions. Whether you’re looking for snow or avoiding it, hike responsibly and within your limits. Get experience hiking in the snow on easy trails first. Prepare for all conditions, understand the risks (such as avalanche zones), and have the right gear. No hike is worth risking your life for.

Checking For Snow on the Trail Video

Past and Future Weather Reports

The first and easy thing to do is to check the weather. If it’s snowing in the area of your hike, there’s probably snow there. If you see snow that’s moved past the area, find a historic radar over the area of your hike and see if snow passed over it.

If you want a premium Gaia GPS membership, HikingGuy readers get a discount. Just visit my gear page for the link.

I also recommend checking the weather for summits or maximum elevations of your hike. Most weather stations are in populated areas, so it can be challenging to find the weather for the backcountry.

The National Weather Service does have forecast locations (and approximations) all over the United States.

You can create a custom forecast area for your hike on the NOAA website.

Mountain Forecast offers altitude adjusted forecasts for many high peaks and summits. The forecasts are based on a weather model and not necessarily actual observations from the location.

Find a Vantage Point

This is a pretty low-tech approach and won’t always be applicable to your hike, but just doing a visual scan of the area can usually offer an idea of the snow cover. In Southern California there are a ton of vantage points that let you see the high mountains. If they have snow, chances are your hike will have it too.

If you don’t live close to the area that you are checking for snow, search Instagram for the location. If there’s snow in the area, you can be pretty sure that people are posting pictures.

NOAA SNODAS

The NOAA offers a map layer of snow data called SNODAS, the Snow Data Assimilation System. In a nutshell, it’s data that predicts the snow depth over the United States. It’s based on a sophisticated computer model that “integrate[s] snow data from satellite and airborne platforms, and ground stations.” It takes many factors in accounts including solid and liquid precipitation, temperature, snowmelt, blowing snow, and existing snowpack. The snow depth is available as color-coded data that users can overlay onto their own maps. It’s updated every 24 hours. In my anecdotal observations I’ve noticed that it’s fairly accurate, especially when used in conjunction with high-resolution satellite photos (more later). You can do a deep dive on the SNODAS model here.

You can see the SNODAS snow layer in action on the USDA Forest Service map here.

The SNODAS model isn’t good at accounting for shade and sun exposure. Generally use it as a guide and know that north facing slopes will generally have much more snow for longer than slopes exposed to the sun.

Gaia GPS SNODAS Snow Layer

Gaia GPS is a navigation tool and application with web, iPhone, and Android versions. It’s a powerful navigation system that also lets you check for snow cover when you have a premium membership. The SNODAS snow layer can be added to your map. Just put it on top of the other map layers and tweak the opacity to see if there is snow on the trail.

CalTopo Custom SNODAS Snow Layer

If you don’t have a premium Gaia GPS membership you can grab the same data with the free CalTopo website. It’s not as elegant but it does the trick. You just have to do a little bit of setup.

Type: WML

Name: Whatever you want

URL Template: https://idpgis.ncep.noaa.gov/arcgis/rest/services/NWS_Observations/NOHRSC_Snow_Analysis/MapServer/export?dpi=96&transparent=true&format=png8&layers=show:3&bbox={left},{bottom},{right},{top}&bboxSR=102100&imageSR=102100&size={tilesize},{tilesize}&f=image

Overlay: Yes

You can create a free CalTopo account and save the SNODAS layer so that you always have it handy.

CalTopo SnoTel Stations

The US Department of Agriculture also has over 800 remote snow measurement systems in watersheds around the United States called SnoTel. You can view each station’s readings on CalTopo with the built-in SnoTel Data later. Just click the layer on, then click on one of the stations on the map for snowfall over the last 1-7 days.

CalTopo Recent Satellite Photography

Checking a recent satellite photo of the area where you want to hike is another great way to do snow reconnaissance. Luckily CalTopo integrates high-resolution Sentinel Satellite imagery, updated every week. I generally overlay the satellite image on top of a trail map. If there is cloud cover, the imagery is not so useful, but there is an archive of past weeks that you can search through too.

snowEvaluator

snowEvaluator is a free option that was built on the Earth Engine Apps platform. It uses weekly Sentinel imagery and then turns the snow cover into a false red, so it’s easier to distinguish snow from clouds. It also takes the satellite imagery with the least amount of clouds, which should help improve accuracy.

Local Reports and Imagery

Looking at a map with snow data is helpful, but it doesn’t give you the condition of the trail and snow. That’s why I try to find as many local sources of information as possible, and if I don’t find them, I ask the community. Each area has its own spots where it congregates online to share, so you’ll probably have to do some searching to find them. Using the region plus “hike trip report” or “trail report” in Google should get you most of the way there. Some places to search are:

Even if the trail looks doable, the roads might be closed. Don’t forget to check local sources for any road closures.

A Quick Note On Avalanches

Understanding avalanches is a whole science in itself and I’m not going to go too deep, but there’s a quick tool you can use to make sure there isn’t avalanche risk on your hike.

Once you know how much snow is on the ground, you can then take a look at steep sections along your trail. The darker terrain sections (orange to purple) are the steepest. If your trail goes beneath or on those slopes, there’s a potential avalanche risk. Note that these gradient visualizations are based on an elevation model and don’t always represent physical features that might also increase the risk of avalanche. If there is already a lot of snow on the ground, new snow can increase the likelihood of an avalanche.

Most avalanches are triggered by the victim, so knowing what conditions to look for is important. If you’re not experienced with winter hiking, you’re best avoiding any avalanche areas until you have more skills under your belt. I highly recommend this book by Bruce Tremper if you want to learn more about avalanches.

Check Avalanche.org to find local avalanche reports near your hike.

Putting It All Together

Here’s the workflow that I use to determine if there is snow on the trail and then what to do.

Get as much data as possible (using the former methods) to determine if there is snow on my hike and where. If there is snow on the route, check the avalanche risk. Check the upcoming weather and make sure there is not more snow coming. Decide “go or no go” for the hike. If I can walk 0n the trail with micro-spikes and there are no obvious dangers, I’ll go. Otherwise I know it will be more of a mountaineering exercise and not a hike. If I do go hiking and the conditions are not what I expected, I’m not afraid to turn around and call it a day. I never put myself in a situation where I have to do something dangerous.

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