Planning for Spring Skiing with CalTopo

When the powder dries up, it doesn’t mean ski season is over- for some people, its just getting started.

While winter has ended prematurely across much of the Western US, there is still time for fun skiing and this guide will cover the layers and tools useful for spring skiing. As the snow line recedes, that means melted out access roads, more predictable avalanche danger, and often more stable weather. For many, it is the time to tackle bigger objectives and explore deeper into the mountains. There are few things as joyful as ripping down soft spring snow in the sun on a remote peak or high volcano!

However, planning for a spring ski adventure looks very different from a typical winter tour. There are three crucial aspects of planning a spring tour that CalTopo can help with:

1. Snowpack
2. Weather
3. Sun Exposure

Snowpack

As spring arrives, the lower elevations typically start to melt out first, along with south aspects. And this year, the snowpack has unfortunately melted out earlier than normal for most of the Western US. Most spring objectives require careful consideration of the state of the snowpack. With any spring tour, you can ask yourself the following questions:

• Roads: Can I drive to where I need for this tour?
• Access: Is there snow where it is needed for access? Or is there a trail if melted out?
• Line: Does the ski line still have sufficient coverage?

Sometimes, you cannot satisfy all three of these questions simultaneously, and compromises can be made. But usually, you can optimize pretty well with careful planning.

Mt. Stuart is a massive, complex peak on the dry side of the Washington Cascades. Its broad south face is a maze of couloirs and gullies. Human powered access is not reasonable in the winter, so it is a classic spring objective. Unfortunately, the steep south aspect often melts out faster than the approach road. So timing this line means waiting as long as possible before the south face melts out, and accepting a few extra miles of skinning or walking along the road. Except in rare circumstances, it is nearly impossible to be able to drive all the way to the trailhead, but still have sufficient snow in the south facing gullies.

The Sentinel Weekly imagery layer in the Base Layers menu on CalTopo is extremely helpful for timing an objective like this. When I skied this line last spring, I watched carefully to see when the ski lines were looking thin, and knew I had to pull the trigger then.

Typically, we are concerned about too little snow coverage. However, there are often approaches where too much snow is a problem. In general, most approaches are best when the transition from no snow to complete coverage occurs as quickly as possible. This setup is found when the snow line is at a point in the route where you quickly gain elevation, although it can also be achieved by changing aspect or terrain at the right point.

Ruth Mountain in the North Cascades requires a 3-4 mile approach up the middle of a low elevation valley, with steep avalanche paths above on both sides. While the snow is melting out of the valley, approaching Ruth would be a constant transition between avalanche debris and dry trail sections through the forest patches. This would be painful and slow, requiring frequent transitions or challenging hiking through the snow. But once it melts out further, you can just hike the dry trail with skis on your back, before reaching full snow coverage in a higher basin. When I skied Ruth in June, we never stepped on snow the entire hike in, until we reached the basin where we could transition completely to skis.

Weather

Like any form of skiing, weather is essential. For spring “corn” skiing, the ideal setup is a week or two of “freeze thaw” conditions – where temperatures go above freezing during the day, and below at night. This melts and consolidates the snowpack, transitioning the snow to melt grains, which resemble corn as they soften in the sun. More than a few inches of fresh snow will usually reset the “corn cycle”, so it is not desirable at this time of year.

While CalTopo does not replace your favorite weather app, its abundant weather stations do include super helpful data on recent weather. In the right hand sidebar, just select “Weather Stations” from the Overlays menu and look for a station near your objective, ideally at a similar elevation.

The weather history is particularly useful for evaluating if a zone has been in a consistent freeze/thaw cycle. The location above is near Tioga Pass and has been seeing night time temperatures just below freezing, with daytime temperatures in the mid 50s. However, you can see that one of the recent nights was warmer, with temperatures never reaching freezing. Although the snowpack can refreeze on clear nights even at temperatures modestly above freezing, this does indicate that the snow conditions the next day would be more prone to becoming mushy much faster than normal. This plot suggests generally favorable conditions for spring skiing.

Down the road at Lee Vining, the overnight temperature is only dropping to 45F. This indicates that it is not really getting cold enough at night for a refreeze. Thus, good skiing would be hard to come by during the day.

Sun Exposure

After a solid refreeze, the key ingredient for ripe corn is solar input – the sun. With the long spring days, east aspects get the first light, and soften first. Then south aspects and west aspects corn up. If the sun is high enough, lower angled north aspects also might soften nicely, usually later in the day.

There’s no magic formula for how long a slope must be in direct sunlight before softening. It depends on a plethora of factors:

• Slope angle: while the sun is lower in the sky in the morning, steep slopes receive more direct sunlight. Thus, steep east aspects usually soften before lower angled east aspects.
• Temperature: A hard refreeze overnight delays softening, and warm daytime temperatures speed it up.
• Cloud Cover: Clouds weaken the refreeze overnight, but also slow the softening during the day.
• Wind: A breeze will also delay softening.

The CalTopo “Sun Exposure” layer in the Overlays menu will show you what slopes are in the sun at any point during the day throughout the year. This layer is incredibly helpful for determining when a slope starts to receive sun.

The SW Chutes of Mt. Adams, a classic corn ski in the Washington Cascades, doesn’t really see any sun until 9 AM. Its aspect, coupled with a high elevation of 9,000-11,000 ft, means that it typically does not reach “corn o’clock” until noon or 1 PM.

An under appreciated element of sun exposure is the refreeze when a slope returns to the shade. If you have ever been caught on a spring descent too late, you will not soon forget the harrowing experience of skiing down a refreezing slope, trying to keep your skis from hooking in the icy crust forming. Here, too, the sun exposure layer is very helpful.

Spring Adventures

For the intrepid skier, spring can be a special time of year where we venture deeper into the mountains. CalTopo offers the tools you need to plan a successful spring ski trip.  Although for many, this season has been tough, there is still time to break out the sun glasses, skinny skis, and have a great adventure!

Author Kyle McCrohan is a CalTopo Educational Ambassador as well as an avid backcountry skier, climber, and storyteller at climberkyle.com.