Winter ski mountaineering and icefield traverse conditions in Southeast Alaska AI-pedia

Southeast Alaska is the narrow coastal strip of Alaska that lies between the Pacific Ocean and the Canadian province of British Columbia. It is often called the "Panhandle". Behind its coastal towns rise the Coast Mountains, which hold some of the largest temperate icefields in North America. A temperate icefield is a large, connected mass of glacier ice whose temperature is at or near the melting point for most of its depth. The best known and most visited is the Juneau Icefield, which begins just north of the city of Juneau and continues across the international border into British Columbia.

Ski mountaineering means climbing and descending mountains on skis, usually away from ski resorts and often on glaciers. An icefield traverse is a multi-day ski journey across an icefield from one side to the other, with the group carrying or pre-placing its food, fuel and shelter. In Southeast Alaska both activities are strongly shaped by the maritime climate, the steep terrain, the fjords, wildlife and the remoteness of the region.

Winter trips are possible but rare and demanding. Winter brings very short days, repeated Pacific storms, a heavy and frequently loaded snowpack, unfrozen salt-water fjords, and long delays for aircraft access. Most traverses are therefore done in late spring, roughly April and May. This article describes the setting, the specific hazards and logistical problems of winter travel, how these compare with late spring, and the wider context of research, land management and climate change.

Geographical setting

The Juneau Icefield

The Juneau Icefield covers about 3,900 square kilometres (about 1,500 square miles). It extends about 140 km (87 mi) from north to south and about 75 km (47 mi) from east to west. It lies in the Coast Mountains, also called the Coast Range. The southern and western parts are in Alaska. The northern and eastern parts are in British Columbia.

The icefield feeds more than 40 large valley glaciers and about 100 smaller glaciers. A valley glacier is a glacier that flows down a mountain valley, like a river of ice. The best known are:

• Mendenhall Glacier, which ends in a lake a short distance from Juneau's suburbs and is one of the most visited glaciers in Alaska.
• Taku Glacier, the largest outlet glacier of the icefield, which flows south-east towards Taku Inlet. It is notable for having advanced during much of the 20th century while most nearby glaciers retreated.
• Lemon Creek Glacier, a smaller glacier near Juneau that is a long-term monitoring site.
• Herbert Glacier and Eagle Glacier, north-west of Mendenhall, which are sometimes used as access routes.
• Llewellyn Glacier, on the British Columbia side, which drains towards Atlin Lake and is the usual end point of a full south-to-north traverse.

The ice is very thick in places. Measurements of between about 240 and 1,400 metres (790 to 4,590 ft) have been reported, with the greatest thicknesses found in the main trunk of the Taku Glacier. The upper icefield is made up of broad, gently sloping snow plateaus divided by ridges and rock peaks called nunataks (summits that stick up through the ice). Notable peaks include the Mendenhall Towers, a group of steep granite spires above the Mendenhall Glacier, and Devils Paw, which lies on the international border and is generally regarded as the highest summit of the icefield.

Other icefields and glaciated areas

The Juneau Icefield is not the only large ice mass in the region. Others include:

• The Stikine Icefield, further south near the towns of Petersburg and Wrangell. It contains steep, technical peaks such as Devils Thumb and Kates Needle.
• The ice south of the main Juneau Icefield, which feeds the tidewater glaciers at the heads of Tracy Arm and Endicott Arm, including the North and South Sawyer glaciers and Dawes Glacier.
• The Glacier Bay and Fairweather Range area, to the north-west, which includes high coastal peaks such as Mount Fairweather and large icefields that drain into Glacier Bay and the open Gulf of Alaska.
• The Chilkat Range and the mountains around Haines and Skagway, which are known for steep ski terrain and helicopter skiing.

Long traverses that link several of these ice masses have been attempted and completed by experienced parties. Such routes must cross the fjords that separate the icefields, which is one of the hardest logistical problems in winter (see below).

Fjords and coastal terrain

Southeast Alaska's coast is cut by deep fjords. A fjord is a long, narrow inlet of the sea, carved by glaciers and usually bordered by steep walls. Tracy Arm and Endicott Arm, south of Juneau, are examples. They form the Tracy Arm–Fords Terror Wilderness, part of the Tongass National Forest. Many fjords end at tidewater glaciers, glaciers whose fronts reach the sea and break off (calve) as icebergs.

Between the fjords and the icefields lie steep valleys covered in dense temperate rainforest at lower elevations, with brush, cliffs, waterfalls and avalanche paths above. This band of terrain, between sea level and the edge of the ice, is often the most difficult and dangerous part of any approach or exit.

Climate and weather

Maritime climate

Southeast Alaska has a maritime climate. This means that the nearby ocean keeps temperatures relatively mild and that precipitation is very high. Juneau is at about 58 degrees north, yet its winters at sea level are much milder than those of inland Alaska at similar latitudes. Rain is common at sea level in winter, while snow falls at higher elevations.

Precipitation increases with height as moist air from the Pacific is forced up the mountains. The icefield receives very large amounts of snow each year. This heavy snowfall is the reason such large glaciers can exist so close to sea level. The same snowfall also creates difficult travel and avalanche conditions.

Pacific storms

In autumn and winter, low-pressure systems from the Gulf of Alaska reach the coast one after another. They bring strong winds, heavy snow at elevation and rain lower down. Gaps between storms may last only a day or two. On the icefield, a storm can mean days of whiteout, deep new snow and winds strong enough to destroy tents. Parties often build snow walls, dig snow caves or use huts where available.

A whiteout is a condition in which cloud, falling snow and a uniform snow surface make it impossible to see the horizon, slopes or crevasses. On a broad, featureless icefield this makes navigation by sight impossible, so travellers rely on compass, map and satellite navigation (GPS).

Taku winds

The Juneau area is known for Taku winds. These are strong, cold, outflow winds that occur when cold, dense air from the interior of British Columbia and Yukon flows towards the coast through gaps in the mountains, especially the Taku River valley. Gusts can be extremely strong, at times reaching hurricane force. Taku winds are associated with clear, very cold weather. On the icefield and its outlet glaciers they can cause severe wind chill, blowing snow and wind slabs (see the avalanche section).

Temperature

Winter temperatures on the upper icefield are colder than in Juneau, but the maritime influence still means that warm spells and rain events can occur during winter, even at moderate elevation. This variability affects both the snowpack and wildlife behaviour. During outflow (Taku) events, temperatures can fall well below freezing at all elevations.

Daylight

Daylight changes greatly through the year. At the December solstice Juneau has about 6 hours of daylight, with the sun low in the southern sky. Steep valleys and fjord walls receive even less direct sun. By late April there are well over 14 hours of daylight, and by late May more than 17 hours, with long twilight periods. Day length affects how far a party can travel, how much time it has to deal with problems, and how safely it can cross complex terrain.

Snowpack and avalanches

Character of the snowpack

The region has a maritime snowpack. Compared with snowpacks in colder, drier inland mountains, it is usually deep, dense, wet and relatively warm. Typical features include:

• Frequent, heavy loading by new snow during storms.
• Rain-on-snow events, when rain falls on an existing snowpack, adding weight and weakening it.
• Melt-freeze crusts that form after warm spells or rain and later freeze.
• Strong wind effects, both during storms and during Taku wind events.

Maritime snowpacks are often thought of as stabilising faster after storms than inland snowpacks. However, weak layers such as buried surface frost or sugary snow near crusts can still form, especially during cold, clear periods such as those caused by Taku winds.

Main avalanche types

Several types of avalanche are especially relevant in the region:

• Storm slab avalanches: a cohesive layer of new snow sliding during or soon after a storm.
• Wind slab avalanches: slabs of snow deposited by wind on lee slopes (slopes facing away from the wind).
• Wet snow avalanches: avalanches in snow weakened by rain or warming, which can be heavy and slow-moving but very destructive.
• Glide avalanches: the whole snowpack sliding on smooth ground such as rock slabs or grass, which can release at any time of day and are difficult to predict.
• Cornice failures: collapses of overhanging snow on ridge crests, which can trigger slopes below.

Where avalanche danger is concentrated

Avoiding avalanche terrain altogether is not realistic in this setting. Fjord walls, the steep margins of the icefields and most of the valleys that lead from the coast up to the ice are avalanche terrain. Many valleys are lined with avalanche paths that run from ridge to valley floor. The snowpack in this zone is often wet and heavy and is frequently reloaded by storms.

The broad, gently angled upper plateaus of the icefield are much less exposed to avalanches, because few slopes there are steep enough to slide. In practice, the most dangerous parts of a trip are usually the ascent from the coast to the icefield and the descent from the icefield at the other end, rather than the time spent on the ice itself. Steep side slopes, icefalls, passes and nunatak flanks on the icefield can still be hazardous.

Avalanche forecasting

Avalanche forecasts in North America usually use the North American Public Avalanche Danger Scale, which has five levels from Low to Extreme. In Southeast Alaska, public forecasting is concentrated near communities and popular backcountry areas, such as the mountains around Juneau. Juneau itself has avalanche paths that reach into urban areas, and local avalanche safety work has a long history there. For the remote icefield interior, the fjords and the long approaches, there is generally no detailed public forecast. Parties must assess the snowpack themselves, using observations, snow tests and weather information.

Glacier hazards

Crevasses and snow bridges

A crevasse is a crack in a glacier, formed where the ice is stretched as it flows over uneven ground or around bends. Crevasses can be many metres deep. They are often hidden by snow bridges, layers of snow that span the opening. A snow bridge may hold a person on skis or may collapse.

The snow cover on the glaciers builds up through the winter and is generally deepest at the end of the accumulation season, in late spring. Early in winter, bridges can be thinner and lower glaciers may have less cover. In late spring, bridges are usually thicker but can weaken during warm afternoons. Many parties therefore travel on glaciers early in the day when the surface is frozen.

Standard practice on Southeast Alaska glaciers is to travel roped together, wear harnesses, carry equipment for crevasse rescue (pulling a fallen person out of a crevasse), and know how to use it. Tour operators that land helicopters on the glaciers in summer generally restrict visitors to marked, guided areas for this reason.

Icefalls and margins

An icefall is a steep, broken section of a glacier where the ice flows over a drop, creating many crevasses and towers of ice called seracs, which can collapse. The edges of the icefields, where glaciers descend steeply towards the valleys, often contain icefalls. Routes on and off the ice are chosen to avoid or minimise travel through them.

Outburst floods

Some glaciers of the Juneau Icefield trap meltwater in basins that can drain suddenly. Since the 2010s, water from Suicide Basin, beside the Mendenhall Glacier, has repeatedly drained through or under the glacier and caused floods on the Mendenhall River. Floods in August 2023 and August 2024 damaged homes in Juneau. These floods happen mainly in summer and early autumn. They illustrate how the icefield margins are changing, but they are not a typical winter travel hazard.

Wildlife

Bears

Southeast Alaska has high populations of both brown bears (Ursus arctos, often called grizzly bears inland and coastal brown bears near the coast) and American black bears (Ursus americanus). Bears are common in the valleys and on the coast, and they sometimes cross glaciers.

Coastal brown bears generally den from roughly November to April. Because winters in Southeast Alaska are mild compared with inland Alaska, denning is less predictable than many people assume. Some bears enter dens late, and some wake up and move about during warm spells. In winter most bears are asleep, but encounters cannot be ruled out. In late spring bears are beginning to emerge, often hungry, and they move down to the coast and lower valleys to feed. Parties carry bear deterrents, store food carefully and pay particular attention at coastal camps and in valley approaches.

Other animals

Mountain goats live on steep cliffs above many fjords and valleys. Their presence can indicate terrain that is also prone to rockfall and avalanches. Marine mammals such as seals often rest on floating ice near tidewater glaciers, which is relevant for parties travelling by boat or packraft.

The fjord problem

Why fjords do not freeze

The fjords of Southeast Alaska are arms of the sea filled with salt water and influenced by tides. Unlike lakes and rivers in colder inland regions, they generally do not freeze over in winter. Some ice may form locally where fresh water floats on the surface, but there is no dependable ice cover to walk or ski across. Fjords with active tidewater glaciers also contain floating glacier ice, ranging from small chunks to large icebergs.

Crossing by water

A traverse that links icefields separated by fjords, or that starts or ends at a fjord head, must cross water. Options include:

• Boat or floatplane support, arranged in advance, which depends on weather and sea conditions.
• Packrafting, the use of a small, light, inflatable boat that a skier can carry in a backpack.

Packrafting a fjord such as Tracy Arm or Endicott Arm in winter means paddling in water that is only a few degrees above freezing, sometimes among floating ice, in a region of frequent strong winds and storms, and with very little daylight. Falling into such cold water can cause cold shock (an involuntary gasp and rapid breathing), loss of muscle control within minutes, and eventually hypothermia. Calving glaciers can also cause sudden waves. For these reasons, winter water crossings are considered among the most serious parts of any winter route in the region. Parties that attempt them typically use dry suits, stay close to shore and plan crossings for calm periods.

Access, logistics and rescue

Getting to the region

Juneau, the state capital, is not connected to the North American road network. It is reached by air or by ferry on the Alaska Marine Highway. Skagway and Haines, to the north, do have road links to Yukon and British Columbia. Atlin, at the northern end of the classic Juneau Icefield traverse, is a small community in British Columbia linked by road to the Alaska Highway.

Getting onto the ice

Common ways to reach the icefield include:

• Skiing from Juneau, for example via the valleys and glaciers close to the city, which involves long approaches through forest and avalanche terrain.
• Helicopter or ski-plane drop-off on the upper glaciers. Flights depend on weather and visibility, and parties may wait days for a suitable window.
• Boat access to fjord heads, followed by a climb up a glacier or valley.

In winter, the short days and the frequency of storms reduce the number of flyable hours. This makes both drop-offs and pick-ups less predictable. Parties usually carry several days of extra food and fuel to cover delays.

Crossing the border

A full traverse of the Juneau Icefield from Juneau to Atlin crosses from the United States into Canada in roadless terrain. Travellers must comply with Canadian entry and reporting requirements, which may mean contacting border authorities in advance or on arrival. The details depend on current regulations and should be checked before a trip.

Shelter

The Juneau Icefield Research Program maintains a network of camps on the icefield that are used during its summer field season. Independent parties generally cannot rely on these buildings and must be self-sufficient, carrying tents or digging snow shelters. In winter storms, a well-built snow cave is often warmer and more secure than a tent.

Communication and rescue

Mobile phone coverage is absent across most of the icefield and fjords. Parties carry satellite messengers or satellite phones. Search and rescue in the region can involve volunteer mountain rescue groups, state troopers and United States Coast Guard helicopters, and on the Canadian side, Canadian agencies. All of these depend on flying weather. In winter, poor visibility and short days can delay rescue for long periods, so parties must be prepared to look after an injured member for several days.

Winter compared with late spring

Why late spring is the usual season

Most Juneau Icefield ski traverses take place in late spring, around April and May. This season is seen as a compromise between the hazards of winter and those of summer:

• Days are long, giving more time for travel and for dealing with problems.
• The snowpack has usually had time to settle and become more stable than in mid-winter, although wet snow avalanches become a concern on warm days.
• The glaciers are at or near their maximum snow cover, so crevasses are generally better bridged.
• Storms still occur but are often less frequent than in autumn and early winter.
• Bears are only beginning to emerge from their dens.

Later in the summer, the snow on lower glaciers melts away. This exposes crevasses and bare ice and makes the lower glaciers and valley approaches harder to travel on skis.

Comparison table

Factor	Mid-winter (about December to February)	Late spring (about April to May)
Daylight in Juneau	About 6 to 8 hours	About 14 to more than 17 hours
Storm frequency	High, with storms often following each other closely	Lower, with longer stable periods more likely
Snowpack	Frequently loaded by new snow; storm and wind slabs common; rain-on-snow possible at mid elevations	Generally more settled; wet snow avalanches on warm days, especially in the afternoon
Crevasse coverage	Building up; may be thin early in the season or on lower glaciers	Usually near maximum, though bridges soften in afternoon warmth
Cold and wind	Colder, with Taku wind events possible	Milder; strong sun and reflected light on snow
Bears	Mostly denned, but some may be active during warm spells	Emerging, often in valleys and along the coast
Fjord crossings	Very cold water, short days, frequent storms	Still cold water, but longer days and calmer periods more likely
Aircraft access	Limited by short days and weather; long delays common	More flying hours; delays still possible

Reasons some parties still go in winter

Winter trips are uncommon, but some experienced skiers attempt them. Reasons include the challenge itself, the possibility of cold, dry snow at high elevation during clear spells, and the solitude of the region in winter. Such trips require advanced avalanche knowledge, glacier travel and rescue skills, cold-weather camping experience and flexible schedules that can absorb long storm delays.

Lift-served and guided skiing nearby

Not all skiing in the region involves icefields. Eaglecrest Ski Area, on Douglas Island across the channel from Juneau, is a municipally owned lift-served ski area. It also gives access to nearby backcountry terrain. The Haines area is well known for helicopter skiing on steep coastal peaks. Its main season is usually in late winter and spring, when days are longer and the snowpack is more consolidated. These activities share the region's maritime snowpack and weather, so many of the same avalanche and weather considerations apply.

Research and history

The Juneau Icefield Research Program

The Juneau Icefield Research Program (JIRP) began in the 1940s, with glaciologist Maynard Miller as a central figure, and has run fieldwork on the icefield for decades. Each summer it brings students and scientists onto the icefield, and its field season has traditionally included a long ski and foot traverse from the Juneau side towards Atlin, with stops at a series of camps. JIRP measurements have built one of the longest records of glacier change in North America.

The Lemon Creek Glacier and Taku Glacier have long mass-balance records. Mass balance is the difference between the snow a glacier gains each year and the ice and snow it loses through melting and calving. Lemon Creek Glacier is one of the reference glaciers used internationally to track glacier change.

The program's summer timing reflects the same seasonal logic that keeps most recreational traverses out of the winter months.

Tourism

The icefield is a major tourist attraction. In the summer cruise season, many visitors are flown in by helicopter for short guided walks on the ice of glaciers such as the Mendenhall and Taku, and dog-sledding camps operate on the ice. These activities are seasonal and generally do not operate in mid-winter.

Land, management and Indigenous peoples

Most of the Alaska side of the icefield and surrounding mountains lies within the Tongass National Forest, the largest national forest in the United States, managed by the US Forest Service. Tracy Arm and Endicott Arm are within the Tracy Arm–Fords Terror Wilderness. On the British Columbia side, parts of the northern icefield, including the Llewellyn Glacier area, are within Atlin Provincial Park. Rules on aircraft landings, commercial guiding and camping vary between these areas. Commercial operators typically need permits.

The region is the traditional homeland of the Tlingit people. The Juneau area includes the traditional territories of the Áak'w Kwáan and T'aaku Kwáan, and the Taku River Tlingit First Nation is based in Atlin on the Canadian side. Many place names in the region come from the Tlingit language, and Indigenous communities continue to have strong cultural, economic and legal interests in the land and waters crossed by traverses.

Climate change and changing conditions

Most glaciers of the Juneau Icefield have been thinning and retreating. The Mendenhall Glacier has retreated a long way since the mid-20th century. The Taku Glacier, long noted as an exception that advanced, has more recently been reported to be losing mass and retreating. Studies of the icefield as a whole have reported accelerating ice loss in recent decades.

These changes affect ski mountaineering and traverses in several ways:

• Lower glaciers are thinner and more broken, and some former access routes have become harder or have changed.
• Retreating glaciers leave steep, unstable moraines (ridges of rock debris) and new lakes that must be crossed or avoided.
• Rain at higher elevations during winter may become more frequent, which would affect snowpack stability and snow quality.
• The snow line and the extent of reliable snow cover on lower glaciers may shift, changing the length of the practical traverse season.

The size and timing of these effects on winter travel specifically are not precisely known. They depend on future climate and are an open question for both scientists and recreational users.

Open questions and debates

• Seasonal choice: experienced users disagree about how much earlier in the season traverses can be done safely, and about the trade-off between colder, drier snow in winter and the longer days and settled snowpack of spring.
• Bear behaviour in mild winters: how far warming winters may shorten or interrupt denning in coastal brown bears is a subject of ongoing interest. It could affect how reliably winter is considered a low-encounter period.
• Forecasting in remote areas: public avalanche forecasting covers only a small fraction of the region's terrain, and there is limited data from the icefield interior in winter.
• Access and use: helicopter and aircraft use for tourism and recreation brings economic benefits but raises questions about noise, wildlife disturbance and wilderness character.
• Changing glaciers: as glaciers retreat, traditional routes, camps and research sites may need to change, and new hazards such as outburst floods may develop.

See also

• Juneau Icefield
• Mendenhall Glacier
• Taku Glacier
• Lemon Creek Glacier
• Juneau Icefield Research Program
• Stikine Icefield
• Tracy Arm–Fords Terror Wilderness
• Tongass National Forest
• Atlin Provincial Park
• Coast Mountains
• Ski mountaineering
• Avalanche
• Crevasse
• Glacial lake outburst flood
• Taku wind
• Packrafting
• Brown bear
• Tlingit