Winter Travel Series #4: Learning About Current and Forecasted Conditions
This is the fourth post in a 5-part series covering our favorite CalTopo layers and tools for planning winter backcountry travel. Each post will dive into a different stage in the process, from learning about the terrain to actually heading out into the backcountry with the mobile app. We will largely be focusing on the web app but many of the layers and tools are also available in the mobile app. Now let it snow!
Learning about current and forecasted conditions
As you get ready to head out into the backcountry, having a good understanding of current and forecasted conditions for the area is essential. Knowing what to expect helps you to choose appropriate terrain and travel routes for a given day as well as pack the right gear. Map layers like avalanche and weather forecasts, weekly satellite imagery, and real time snowpack data make it easy to display this information directly in your CalTopo map.
Let’s dig more into how you can use each of these layers (as well as some other tools) to effectively plan for winter travel.
Get the avalanche forecast
A great starting point for learning about current and forecasted winter conditions is the avalanche forecast. Developed in close partnership with the American Avalanche Association, USFS National Avalanche Center and Avalanche Canada, the avalanche overlay displays real time regional avalanche forecasts from local avalanche forecasting centers in the US and Canada.
Each zone is color coded to reflect the current danger rating. Clicking on the zone brings up a dialog with a summary of the current avalanche forecast as well as links to the forecasting center and full forecast. We highly encourage users to click through to view the forecast details and discussion and dive deeper into the avalanche forecast.
The avalanche forecast provides information about any expected avalanche problem(s) and can be very useful for identifying appropriate terrain for the given conditions. We recommend that all users seek out professional training to learn more about traveling through avalanche terrain. Our partners at the American Avalanche Association and Avalanche Canada have some great resources to get you started or continue your education- make sure to check them out!
Investigate current and forecasted weather
Whether you are chasing the deepest powder or trying to decide if you should pack that extra puffy, it is also important to have a solid understanding of what to expect from the weather before you step out the door.
The weather shading overlay displays National Weather Service forecasts using a color gradient along with the numerical forecast for each forecast grid at higher zoom levels. You can choose between forecasts for 24-hour low or high temperatures, precipitation, snowfall, and max wind speed and gusts.
With this overlay you can easily visualize forecasted weather right in your CalTopo map. This can be helpful for choosing where you may want to go on a particular day as well as what to pack. However sometimes you need a more detailed weather forecast for an area. To do this, right click on the area you are interested in and then select NOAA Forecast from the dialog that appears. The full forecast for that area will open in a separate tab, allowing you to dig deeper into what to expect.
There is one weather factor in particular that is an especially important consideration for winter travel: WIND. Yes, the dreaded 4-letter word. It can have a big impact on snow, your terrain choices (which anyone who has been blasted by high winds on an exposed ridge can attest to), and what layers you decide to bring. With the wind plot overlay, you can view current and forecasted wind speed and direction directly in your map.
This overlay can help you to identify areas that may be sheltered from the wind versus areas that are exposed, spots where wind loading may be occurring, and more. As with any digital mapping tool, the wind plot overlay is most useful when combined with physical observations of the terrain, such as looking for signs of wind-drifted snow. Again, we recommend seeking out professional training to learn more about traveling through avalanche terrain.
Track snow coverage and depth
Snow coverage is often a big question mark in the early and late season. Is there snow covering the road to the trailhead or has it melted out? How far am I going to have to hike before I hit the snow line? Is a particular couloir still holding snow?
Available to pro accounts and higher, the Sentinel Weekly layer can provide insight into current and past snow coverage alongside all your other mapping data. The imagery for this layer comes from the Sentinel satellite program, which captures imagery of every spot on Earth from the same angle every 5 days. It has 10-m horizontal resolution which is good enough to zoom in on an individual snow patch or find the snow line.
The Sentinel Weekly layer also has options for false color visualizations. False color green is particularly useful for distinguishing between snow and bare ground. Furthermore, stacking Sentinel imagery with relief shading and/ or a topographic map like MapBuilder Topo allows you to figure out exactly what peak or slope you are viewing.
In addition to snow coverage, snow depth and quality are also important considerations for planning winter travel. Available to pro accounts or higher, the weather stations overlay allows you to display real time snowpack data, such as snow depth and snow water equivalent (SWE), from both SNOTEL and non-SNOTEL sensors in the area. You can view the current sensor readings or go deeper and display an interactive 7-day sensor history to examine how the snow has changed over the past week at that location.
Now it’s your turn! Are there any layers we missed that you find particularly useful for learning about current and forecasted conditions in the winter? Question or comments? Leave them below.
Next week will be the last installment of the winter travel series. We’ll be covering using the mobile app in the backcountry. Until then, happy mapping!
I didn’t realize snowfall forecast was on the weather overlay, that’s awesome! I have 1 tip and 2 questions/requests. The “False Color Green” Sentinel visualization is particularly useful for me to distinguish between snow and clouds; I’m sure there are white rocks that look like snow somewhere, but not in Washington! Is there a way to tell how old the forecast is? E.g. it currently shows 4 inches of snow due at Stevens Pass in the next 24 hours, but NOAA says there’s a 0% chance of precipitation over that period. Looking at SNOTEL data, I can confirm that this 4″ of snow fell this morning (12 hours ago). I’m also wondering if it would be possible to display the previous, say, 48 hours snowfall and average wind direction/speed (from the forecast 48 hours ago). Weather sites give you snowfall data and wind speed, but it’s cumbersome to scroll around interpolating that data. And it seems I have to leave CalTopo to find historical wind direction data from these stations. These overlays would complement on-the-ground avalanche observations nicely. Thanks for another useful article!
Hey Michael! Totally agree about the “false color green” layer. It’s pretty rad.
CalTopo checks the forecast information every 30 minutes (though the source data might not be updated that often). However, we had a little trouble with that sync process that probably affected it at the time that you were looking at that forecast.
We would love to have some of that historical data also, but we run into the same problems you do as an individual. We may be able to build something eventually but sadly it lives a ways down on the priority list.