As atmospheric rivers crashed into the High Sierra during the 2022-23 winter, I had two primary reactions. I was:
- In awe of the precipitation amounts, with totals eventually reaching 237 percent of the state-wide average snow water equivalent on April 1; and,
- Increasingly concerned about the impacts of this record-breaking snowpack on the summer backpacking season — and also on my livelihood, since I was planning to operate seventeen guided trips in this area starting in the third week of July.
In 2023 backpacking trips in the High Sierra will be more difficult and risky than identical itineraries in past seasons. However, it’s possible to accurately predict, entirely avoid, and/or safely manage the challenges. Personally, I think this approach is more productive than succumbing to fear mongering (this 2018 post remains relevant today) or letting fears of the unknown grow out of proportion.
In this post I will explain how to have safe and fun trips in the High Sierra by explaining the:
- Likely conditions, and
- Implications of these conditions on trip planning, gear selection, and essential skills.
This post shares content with the extensive early-season tutorial that I wrote in 2017. This one is more succinct and updated, and reflects six additional years of gained backcountry wisdom.
What are the likely conditions?
In normal years
After winters that track close to the the historical averages, in the high country of Sequoia-Kings, Inyo, Emigrant, and Yosemite, we’d expect:
- Water levels to peak around June 1 and to be reasonably safe by July;
- Snowpack to melt off throughout June, leaving only small patches to finish melting in July and August;
- Mosquitoes to emerge in July, when the groundwater finally warms up, and fade in August as their breeding areas dry out.
The arrival of normal conditions will be significantly delayed this season. Instead, most backpackers will experience some “early-season conditions” that normally prevail in May and June that blur the lines between backpacking and mountaineering. Specifically, I’m expecting:
1. More extensive snow coverage, because it will take longer for it to melt off.
Many more weeks of summer temperatures will be required to melt this extreme snowpack. High and north-facing slopes will probably remain snowbound into next winter. As a result, expect:
- Slower travel, due to demanding navigation, awkward sun cups, inconspicuous trail corridors, and a generally slippery and punchy walking surface. In May and June, before the snowpack fully consolidates, post-holing will be commonplace in the afternoons, or earlier after warm nights.
- Extreme sun exposure, especially when above tree line, because snow is highly reflective.
- Increased risk of injury due to little slips, big falls and slides, collapsing snow bridges, rotten rock moats, and post-holing onto unknown surfaces below.
- Large cornices on the leeward side of steep passes such as King Col or Longley Pass.
Another condition indirectly related to the long-lasting snow coverage will be an abnormally high number of blowdowns. Storms that bring heavy moisture also usually arrive with heavy winds, causing trees to fall.
2. Overabundant groundwater
Some of it will percolate into the soil, which is parched after multiple years of drought. But because the High Sierra is composed of impervious granite and because the high country has little top soil, most of it will flow into streams and creeks that eventually form large rivers like the Kern, Kings, San Joaquin, Merced, and Tuolumne. As a result, expect:
- Relatively swift and/or deep water crossings;
- Flooded meadows and saturated ground; and,
- Wet feet, for most or all of the day.
3. A delayed and long-lasting mosquito season
The bugs will hatch after the groundwater becomes warm enough. The volume of cold snowmelt will delay this from happening on a mass scale.
Once the mosquitoes emerge, they probably will stick around until the first frosts in late-September or early-October because many areas will never dry out this season.
Mosquitoes are most active in the evening, seeming to enjoy their supper while you’re having yours. They don’t like temperatures below about 50 degrees (like at night) and they struggle in strong winds.
4. Highly variable conditions
Snow levels, snow consistency, snowmelt rates/river levels, and bug pressure will change throughout each day and from week to week, and vary too with elevation and slope aspect. These dynamics need to be considered when planning whole trips ahead of time and when planning each day.
Trip planning at home
In advance of your trip, what changes should be made and how can conditions be monitored?
Itineraries and permits
- Keep tabs on land agency press releases and social media accounts to monitor openings, closures, and developments. For example, Yosemite recently subtly indicated that a late-June or early-July opening of Tioga Road was unlikely, putting all Tuolumne Meadows wilderness permits at risk through mid-July-ish.
- Soloists and small groups on non-commercial trips might consider obtaining walk-up permits rather making reservations on Recreation.gov, so that plans can remain flexible until the final weeks before. To avoid last-minute rushed planning, have prepared a Plan A, B, and C. Put the unused plans on a shelf for later in the season or for another year.
- Identify obstacles on your route for which you will be under-skilled or under-equipped, like excessive snow coverage, swift crossings, or steep snow-covered passes. Have detours ready, or plan a new route that is lower and that poses fewer challenges.
- Frontload the most difficult elements early in the trip so that you have time to reverse your route. Normally, these sections would go at the end, when you’ve eaten through your food and found your trail legs. But in these circumstances, you may be pressured into doing something foolish so that you exit on time.
- Reduce your expected mileage and vertical each day, to account for slow travel and potential delays. If you end up being too conservative, eat up time with side trips and summits.
To monitor snowpack across the western US, throughout the winter I primarily use:
- For California, the Daily Regional Snowpack Plots from the California Department of Water Resources, and
- For all other states, the Interactive Map from USDA.
When I’m planning early-season trips though, another data source becomes much more valuable: Sentinel Satellite imagery. It gives me access to:
- Current snow coverage, using the most recent imagery; and;
- Historical snow coverage, using the archives.
CalTopo (long-term review) includes Sentinel imagery in its Pro subscription ($50 per year) and has imagery stretching back to January 2017. Select “Sentinel Weekly” base in the Base Layers dropdown menu. New imagery is uploaded weekly.
Imagery from 2017 and 2019 will best inform you of likely snow coverage in 2023. Conditions this season will likely be a few weeks behind these other two seasons, since the 2022-23 was notably wetter. The exact delay will became more evident in late-June or July when more bare ground emerges.
Real-time data for the most renown crossings in the High Sierra — like the South Fork of the Kings between Pinchot and Mather Passes, Bear Creek north of Selden Pass, and Rancheria Creek in Yosemite’s Kerrick Canyon — is unavailable.
Gauges further downstream are suggestive of what’s happening upstream. Refer to my High Sierra Creek Hazards resource for a list, under the section “Data: Current Levels.”
Speaking of, the Hazards list and map is a definitive resource. Use it before you go when planning your route, and as you go to set your expectations and daily schedule.
For the information about current bug pressure, read recent online trip reports and call wilderness offices. But, honestly, these resources are not consistently accurate — rangers may not get out as much as you’d think, online information may not be timely, and the reported conditions may not be relevant to your own itinerary. It’s more productive to simply:
- Be properly prepared for bug pressure; and,
- Understand where and when they are most likely to be — near slow or standing water, in warmer temperatures, with little wind, and especially in the evening.
Compared to a normal summertime kit, what changes should be made?
For sun protection, have:
- Full-length hiking pants
- Long-sleeve hiking shirt with a hood (which is better than a collared shirt with a large hat)
- Sun gloves
- Glacier goggles, or at least dark wraparound sunglasses
- Zinc-based sunscreen for exposed lips and facial skin
For bugs, I recommend at least having a:
- Factory-treated permethrin hoody like this one from LL Bean
- Headnet made of mosquito mesh (not no-see-um)
- Gaiters or treated socks, because mosquitoes are weirdly attracted to nasty shoes and socks
Treated pants are optional. Bites below the waist are much less common, probably because mosquitoes struggle to get through the fabric.
You may opt to bring shorts, because they’re more airy and less restrictive than pants. However, they offer no defense against bugs or sun, leaving their usefulness to bug-free wooded sections.
My experience is that DIY permethrin treatments are less effective, in terms of overall effectiveness and in longevity. If you have beloved non-treated hiking clothes, send them to Insect Shield ($9 per item or $120 for 10-15 items).
Hiking shoes should have a/an:
- Aggressively lugged outsole, for better traction on slick snow;
- Durable upper, for abrasion resistance while kicking steps and wearing crampons;
- Breathable upper, for rapid dispensing of water after crossing creeks and walking through flooded meadows; and,
- Stiff midsole, for better edging and easier step-kicking.
Carry two pairs of socks:
- One pair for hiking that gets wet and stays wet; and,
- One pair for sleeping that stays dry inside your pack during the day.
I prefer wool socks, which are observably warmer (but not “warm”) than synthetic fibers like nylon.
For additional thoughts on early-season footwear, read this post.
Shelter and sleep system
- If the bugs have hatched, then bring your shelter’s bug-resistant inner or a water-resistant bivy sack. Defending yourself from a lone mosquito with just a headnet is stupid light.
- Have a reliably waterproof floor or groundsheet so that you can sleep on soggy ground.
- Bring a warmer sleeping pad (e.g. XLite instead of Uberlite) in case you must camp on snow.
Even though you may be camping on snow and be surrounded by snow, the weather in the High Sierra in July and August is typically benign. My goal each season is to cowboy camp every night; for nights when I can’t, I have an open-sided A-frame tarp.
This is an essential item for early-season conditions. In addition to their normal usefulness, they’re good for:
- Extra traction on slick snow
- A third and fourth point of contact when crossing streams
- Probing snow bridges and rock moats before weighting them
- Self-arresting and glissade-braking on moderate slopes, in lieu of an ice axe
Ultralight trekking poles like the Gossamer Gear LT5 should left at home. Instead, go with robust poles like the Black Diamond Alpine Carbon Cork (long-term review) or the Cascade Mountain Tech Quick Lock (long-term review).
Remove the mud baskets and the snow baskets. With baskets, their functionality is partially lost. For example, they’re less effective for probing snow and they add drag while crossing creeks.
- Snowshoes may be helpful in June, before the snowpack has fully consolidated. But it’d be more productive (and lighter) to start before dawn each day, rest in the afternoon, and put in more miles in the evening after the snow has firmed up again.
- By July the snowpack is very consolidated, and extra floatation is not helpful. However, be careful of rotten snow that is melted through (from the top and bottom), like at the edges of snow fields.
- Bring traction if you expect extensive snow travel or isolated sections of high-risk snow travel.
- The lightest option worth consideration are the Kahtoola Microspikes (and similar). They have good purchase on firm snow surfaces and flatter ground, but flounder in looser snow and on steeper grades.
- The Kahtoola K-10 (and similar) are heavier and may be overkill for easy itineraries, but they’re much more capable.
- If your route includes steep slopes with fall potential, an axe is helpful if not required.
- For regular use, select a heavier axe with a longer shaft like the Black Diamond Raven Pro (or similar).
- For just-in-case purposes, an ultralight axe like the Petzl Glacier Literide (or similar) may be enough.
You’ve planned a practical route and you’ve selected appropriate gear. To have a successful trip, skills are the final thing you need.
Once out there, don’t feel compelled to stick to your plan. Instead, be ready to:
- Adjust to the actual (not predicted) conditions, like by adding or removing distance, vertical, and difficulty;
- Turn around if you’re excessively uncomfortable or at risk. This is an important skill; it’s a sign of wisdom and maturity, not failure.
When making decisions, keep in mind the abilities of your weakest group member. The plan must be appropriate for every person in the group, not most of them.
- Start early each day, to take advantage of the snow having firmed up (or frozen) overnight. Once the snow softens, the snow becomes punchy and slushy, and post-holing will be more common.
- Avoid steep slopes in the morning after cold nights, because they will be frozen and have higher fall risks. Give these passes some time to soften up.
- Attempt to finish your day at lower elevations, where you are more likely to find snow-free and dried-out ground.
- Be aware of collapsing snow bridges, unsupportive rock moats and snowpack edges, wet avalanches, steep cornices, among other hazards.
- Comfort on steep snow is personal, and confidence is gained with experience. Beginners with a snow sports background (e.g. skiing, snowboarding) will probably take to it more quickly.
Specific skills to learn include:
- Kicking steps,
- Using the “edges” of your shoes for stability on steep slopes
- Boot skiing
- Self-arresting with an axe and with trekking poles
- Self-belaying with an axe
- Chopping steps (very rare in summer conditions)
- If a trail is snow-covered above treeline, it’s de facto off-trail navigation. Know how to use your navigational tools: topographic map, magnetic compass, time piece, altimeter, and GPS.
- Below treeline, it’s more efficient to follow the trail even if it’s snow-covered. Use clues like saw cuts, constructed benches, and old blazes to follow the corridor.
For more early-season navigation tips, read this post. For my definitive tutorial on navigation, go here.
Summertime avalanches are very rare, and this is not the risk that keeps me up at night. However, it’s still helpful to know the warning signs for wet slab avalanches:
- Slopes between 25 and 35 degrees
- Recent avalanches in similar conditions
The slope-angle shading overlay in CalTopo can help you identify slopes.
Expect wet feet everyday, perhaps all day. And often very cold, too. It’s essential to take care of them. Follow this regimen.
To keep my feet warm and dry in camp without needing to carry dedicated camp shoes, I bring 2 mil bread bags. We buy these bags for our clients, available in 100-count only. Here’s the routine:
- After arriving in camp, I remove my shoes and socks to let my feet dry out.
- Once they’re dry, I put on my dedicated sleeping socks, and I layer the bread bags over them.
- I put my entire foot (with dry sock and bread bag) back into my wet hiking shoes.
Take crossings seriously. They can be enormously risky, and in 2017 were responsible for two hiker deaths.
Learn to predict the size and swiftness of crossings:
- Water levels will be highest in the evening, carrying a full day of melt.
- The volume of snowmelt is proportional to a watershed’s size, with some variability based on slope aspects and elevations.
- Where creeks drop elevation quickly, the flow will be swift. Through flat-bottomed meadows, they meander slowly.
- Higher in a watershed, crossings will be smaller, because the snowmelt has not yet fully collected.
Do not assume that the official trail crossing is safe. Instead, learn to identify safer options, and be willing to invest time in scouting trips up and down the creek where it:
- Is wide and slow, not narrow and fast
- Divides into multiple braids, separated by islands or bars
- Has no hazards downstream like waterfalls or strainers
- Is bridged by large logs or sturdy snow
- Has slow-moving eddies on both shores, so that you can easily step in and climb out, instead of cut-banks that indicate deep and swift flows
- Has a gravel-y bed surface, not cobbles or boulders
- Lends itself to crossing downstream at a 45-degree angle, which requires infinitely less energy than crossing perpendicularly or especially upstream.
When crossing solo, use trekking poles to maintain a tripod at all times, with three points of contact, e.g. two legs and one pole, one leg and two poles.
Groups can cross creeks that soloists cannot, or not as safely. Specific techniques include the:
- Eddy or train method, demonstrated here
- Triangle method, shown in this image
- Arm-in-arm, like in this image
For more river crossing discussion, read this post.
Mosquitoes are annoying but entirely manageable:
- Avoid the areas where they are most likely to be, especially when selecting a camp.
- Let your equipment protect you, like your permethrin-treated clothing, headnet, and fully enclosed shelter.
- Accept it for what it is. It may be satisfying to swat at or kill mosquitoes, but that has no effect — they are plenty more where they came from.
I worked in the eastern Sierra back in 1983 as a Wilderness Ranger in the Hoover Wilderness. The prior winter was a record breaker. People should realize the East Side will hold the snow much longer than the more exposed west side. Where I worked, most trails above 8000 feet were buried in snow until the mid to late August. I remember several hikers getting injured falling through snow. Be careful and be prepared!
I appreciate you chiming in with your experiences from that season. 1982-83 is the only winter in living memory that matches 2022-23, and I don’t feel like I’ve heard much from those who lived it.
I’m old enough to have been out there in the summers of 1982 and 1983, both. I was a junior high school kid, though, trailing after my dad. I doubt we would have gone until July of those years though I should look at the old photo albums for dates and to compare with areas I’ve gotten to know better since. Anyway, we were crossing snow for significant portions of any given day, and we did a lot of cross country, but we did not need traction or ice axes for anything. I know that’s not very specific but it is a memory of sorts.
I skied Roper’s SHR this April. The snow conditions were insane. I’m unsure the sun will make too much of a dent on snow levels in some places. I really hope people take the necessary precautions when doing water crossings.
The snow completely changed the topography of the terrain. Map reading was a bit harder than normal. I used CalTopo for route and position verification and Fatmaps for the 3D imagery.
All the passes were steep, but Mather Pass was very steep. Hopefully it will flatten out as the sun melts the snow. I think becoming more nocturnal and moving at 0200 when the snow is much harder will be the way to go. Unfortunately you miss the views but the travel will be faster.
Im also curious how the big density will be. I was also guessing mosquitoes are going to be very bad.
luv ya work andy skurk