Digging a snowpit on Taku Glacier, in Alaska to measure snowpack depth and density
Graph of changing Wyoming Snowpack

Snowpack forms from layers of snow that accumulate in geographic regions and high elevations where the climate includes cold weather for extended periods during the year.

- Snowpack

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Rapid flow of snow down a slope, such as a hill or mountain.

A powder snow avalanche in the Himalayas near Mount Everest.
Heavy equipment in action after an avalanche has interrupted service on the Saint-Gervais–Vallorcine railway in Haute-Savoie, France (2006).
The terminus of an avalanche in Alaska's Kenai Fjords.
Loose snow avalanches (far left) and slab avalanches (near center) near Mount Shuksan in the North Cascades mountains. Fracture propagation is relatively limited.
15 cm deep, soft slab avalanche triggered by a snowboarder near Heliotrope Ridge, Mount Baker in March 2010. Multiple crown fracture lines are visible in the top-middle of the image. Note the granular characteristic of the debris in the foreground that results from the slab breaking up during descent.
Avalanche on Simplon Pass (2019)
In steep avalanche-prone terrain, traveling on ridges is generally safer than traversing the slopes.
A cornice of snow about to fall. Cracks in the snow are visible in area (1). Area (3) fell soon after this picture was taken, leaving area (2) as the new edge.
Avalanche path with 800 m vertical fall in the Glacier Peak Wilderness, Washington state. Avalanche paths in alpine terrain may be poorly defined because of limited vegetation. Below tree line, avalanche paths are often delineated by vegetative trim lines created by past avalanches. The start zone is visible near the top of the image, the track is in the middle of the image and clearly denoted by vegetative trimlines, and the runout zone is shown at the bottom of the image. One possible timeline is as follows: an avalanche forms in the start zone near the ridge, and then descends the track, until coming to rest in the runout zone.
After surface hoarfrost becomes buried by later snowfall, the buried hoar layer can be a weak layer upon which upper layers can slide.
After digging a snow pit, it is possible to evaluate the snowpack for unstable layers. In this picture, snow from a weak layer has been easily scraped away by hand, leaving a horizontal line in the wall of the pit.
United States Forest Service avalanche danger advisories.
Snow fences in Switzerland during summer.
Avalanche blasting in French ski resort Tignes (3,600 m)
Avalanche warning sign near Banff, Alberta
Radar station for avalanche monitoring in Zermatt.

Avalanches can be set off spontaneously, by such factors as increased precipitation or snowpack weakening, or by external means such as humans, animals, and earthquakes.


Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes.

Norwegian train plowing through drifted snow
Extratropical cyclonic snowstorm, February 24, 2007—(Click for animation.)
Frontal snowsquall moving toward Boston, Massachusetts
Cold northwesterly wind over Lake Superior and Lake Michigan creating lake-effect snowfall
Freshly fallen snowflakes
An early classification of snowflakes by Israel Perkins Warren
An animation of seasonal snow changes, based on satellite imagery
New York City during a 2016 blizzard, which
 produced local wind gusts up to 42 mph and dropped 27.5 in of snow, breaking the city's one-day snowfall record.
Snow-covered trees in Kuusamo, Finland
Fresh snow beginning to metamorphose: The surface shows wind packing and sastrugi. In the foreground are hoar frost crystals, formed by refrozen water vapor emerging to the cold surface.
Firn—metamorphosed multi-year snow
Snow drifts forming around downwind obstructions
A powder snow avalanche
Snowmelt-induced flooding of the Red River of the North in 1997
Snow pit on the surface of a glacier, profiling snow properties where the snow becomes increasingly dense with depth as it metamorphoses towards ice
Snowfall and snowmelt are parts of the Earth's water cycle.
Traffic stranded in a 2011 Chicago snowstorm.
Winter conditions on Ontario Highway 401 in Toronto due to a snowsquall.
Deicing an aircraft during a snow event
Satellite view of the Indus River, showing snow in the Himalayas, which feeds it, and agricultural areas in Pakistan that draw on it for irrigation.
Extreme snow accumulation on building roofs
Icings resulting from meltwater at the bottom of the snow pack on the roof, flowing and refreezing at the eave as icicles and from leaking into the wall via an ice dam.
Alpine skiing.
Algae, Chlamydomonas nivalis, that thrive in snow form red areas in the suncups on this snow surface
Arctic fox, a predator of smaller animals that live beneath the snow
Trucks plowing snow on a highway in Missouri
Airport snow-clearing operations include plowing and brushing
Swiss low-profile, train-mounted snowplow
Bivouac of Napoleon's Grande Armée, during the winter retreat from Moscow
Finnish ski troops during the invasion of Finland by the Soviet Union
Army vehicles coping with snow during the Battle of the Bulge of World War II.
Norwegian military preparations during the 2009 Cold Response exercise
Navy SEALs training for winter warfare at Mammoth Mountain, California.

As snow accumulates into a snowpack, it may blow into drifts.

Mount Waterman

For the mountain by this name in Antarctica, see Mount Waterman (Antarctica)

Mount Waterman from the east
Mt. Waterman in March, 2000

In February 2005 there was 3 to 6 ft snowpack, and then another 10 to 12 ft of powder fell.

New Brunswick

One of the ten provinces (and three territories) of Canada.

Fort Beauséjour at the Isthmus of Chignecto. The French built the fort in 1751 in an effort to limit British expansion into continental Acadia.
A romanticized depiction of the arrival of the Loyalists in New Brunswick
An Intercolonial Railway bridge, 1875. The railway was established as a result of Confederation.
A provincial welcome sign in English and French, the two official languages of the province
Topographic map of New Brunswick
Furbish's lousewort is a herb endemic to the shores of the upper Saint John River.
The Hopewell Rocks are rock formations located at the upper reaches of the Bay of Fundy, near Hopewell Cape.
View of the Appalachian mountains from Mount Carleton Provincial Park
Population density of New Brunswick
The province's distribution of English and French is highly regional.
Uptown Saint John is a commercial hub and seaport for the province.
A New Brunswick pulp mill owned by J. D. Irving
Sir Howard Douglas Hall at the University of New Brunswick is the oldest university building still in use in Canada.
The New Brunswick Legislative Building serves as the meeting place for the provincial legislative assembly.
The Imperial Theatre in Saint John hosts the productions of the Atlantic Ballet Theatre of Canada and Theatre New Brunswick.
The Owens Art Gallery at Mount Allison University is the oldest university-operated art gallery in Canada.

Evidence of climate change in New Brunswick can be seen in its more intense precipitation events, more frequent winter thaws, and one quarter to half the amount of snowpack.

Mount Adams (Washington)

Potentially active stratovolcano in the Cascade Range.

Mount Adams from Wasco County, Oregon
Meadows at Mount Adams Wilderness
Heavily crevassed glaciers on the southeast side of the mountain
Glaciers of Mount Adams
Deep crevasses and icefalls on Adams Glacier
Aerial view of the south face from across the Columbia River Gorge
Trout Lake (Trout Lake Creek) reflecting Mount Adams near the small town of Trout Lake
Takh Takh Lava Flow below Mount Adams
Mount Adams, Washington simplified hazards map showing potential impact area for ground-based hazards during a volcanic event.
Rock and ice debris avalanche that occurred on October 20, 1997, on the east side of Mount Adams.
The South Climb, or South Spur climbing route on Mount Adams along Suksdorf Ridge
The Northeast face as seen from Devils Garden
High Camp at Killen Meadows, high on the slopes of Mount Adams. Adams Glacier cascades down the rocky chute from the summit icecap
Mount Adams and the Mazama Glacier from Bird Creek Meadows, in the Mount Adams Recreation Area.
Adams Glacier descends from the summit ice cap near the center of this view from the northwest.
Takhlakh Lake on the northwest side of Mount Adams
Albert Bierstadt, Mount Adams, Washington, 1875, Princeton University Art Museum
Thunderbird on a Totem Pole
Reid's map from his survey of Adams in 1901
Cascadians climbing party before starting the ascent of the east side of Adams
Gotchen Creek Guard Station ca. 1911
US Forest Service lookout on the summit, August 9, 1922.
Level IV ecoregions, Cascades
Towering lenticular clouds over Mount Adams
Lupine on Adams
Hoary marmot above the tree line on Adams
Gray-crowned rosy finch high up the slopes on Adams

The snowpack at Potato Hill starts building in late October to early November and the last of the snow generally melts by the beginning of June, but occasionally lingers into July.


All-encompassing term for those portions of Earth's surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets, and frozen ground (which includes permafrost).

Overview of the cryosphere and its larger components, from the UN Environment Programme Global Outlook for Ice and Snow
Extent of the regions affected by components of the cryosphere around the world from the IPCC Fifth Assessment Report
From The Cryosphere (2021 survey): Earth lost 28 trillion tonnes of ice between 1994 and 2017, with melting grounded ice (ice sheets and glaciers) raising the global sea level by 34.6 ±3.1 mm. The rate of ice loss has risen by 57% since the 1990s−from 0.8 to 1.2 trillion tonnes per year.
Representation of glaciers on a topographic map

Snow cover is an extremely important storage component in the water balance, especially seasonal snowpacks in mountainous areas of the world.

Flagstaff, Arizona

City in, and the county seat of, Coconino County in northern Arizona, in the southwestern United States.

Flagstaff's eponymous flagstaff
The Bank Hotel, also known as the McMillan building, in 2012
Benches commemorating Flagstaff's traditional labor forces in Heritage Square
Local rock strata monument in Heritage Square of downtown Flagstaff
Köppen map of Arizona (Oregon State University, 2016)
1929 Baldwin Locomotive No. 12
Flagstaff's visitors center at the railroad depot
Weatherford Hotel with its pine cone and a countdown in December 2010
Northern Arizona University's Walkup Skydome and central campus
Flagstaff City Hall
The north campus area of NAU, showing the Science and Health buildings (center) and the Liberal Arts building (bottom right)
Roadsigns in downtown Flagstaff
Flagstaff airport

However, due to the infrequent and scattered nature of the snowstorms, persistent snowpack into spring is rare.

Tree line

Edge of the habitat at which trees are capable of growing.

Tree line above St. Moritz, Switzerland. May 2009
In this view of an alpine tree line, the distant line looks particularly sharp. The foreground shows the transition from trees to no trees. These trees are stunted in growth and one-sided because of cold and constant wind.
This map of the "Distribution of Plants in a Perpendicular Direction in the Torrid, the Temperate, and the Frigid Zones" was first published 1848 in "The Physical Atlas". It shows tree lines of the Andes, Himalaya, Alps and Pyrenees.
Alpine tree line of mountain pine and European spruce below the subalpine zone of Bistrishko Branishte, with the surmounting Golyam Rezen Peak, Vitosha Mountain, Sofia, Bulgaria
An alpine tree line in the Tararua Range
Treeline on a mountain in the Canadian Arctic
Coniferous species tree line below Vihren Peak, Pirin Mountain, Bulgaria
Dahurian larch growing close to the Arctic tree line in the Kolyma region, Arctic northeast Siberia
View of a Magellanic lenga forest close to the tree line in Torres del Paine National Park, Chile
Trees growing along the north shore of the Beagle Channel, 55°S.

Treelines on north-facing slopes in the northern hemisphere are lower than on south-facing slopes, because the increased shade on north-facing slopes means the snowpack takes longer to melt.

Fairbanks, Alaska

Home rule city and the borough seat of the Fairbanks North Star Borough in the U.S. state of Alaska.

The fledgling settlement of Fairbanks as it appeared in 1903. The buildings shown are likely those of E. T. Barnette's trading post.
Photo taken by Elisabeth Meyer in 1955, looking easterly from Second Avenue and Cushman Street. The now-abandoned Polaris Building, the tallest building in Fairbanks since its completion in 1952, is in the background.
First Family Statue near Visitor Center, Fairbanks, Alaska
Fairbanks Visitor Center in Fairbanks, Alaska
Satellite image of Fairbanks in 2021
The Fairbanks area in winter, looking north. The Tanana River stretches across the photo south of the city; the airport is west of the city.
Baseball facilities at Growden Memorial Park
Fairbanks' Patrick Cole City Hall, originally constructed in 1934 as a school building, replacing a wooden structure which burned down. Known colloquially as "Old Main", the building housed classrooms until the mid-1970s. Fairbanks North Star Borough School District administrative offices occupied the building until the city government took it over in 1995.
Fairbanks Memorial Hospital
Trans-Alaskan Pipeline, approximately 10 mi north of Fairbanks, Alaska
Fairbanks North Star Borough School District headquarters
The newest bridge across the Chena River in Fairbanks, Alaska, is the Veteran's Memorial Bridge, which opened in November 2012.
Aerial view of Fairbanks International Airport
Alaska Railroad train arrives at Fairbanks station
The northern lights just north of Fairbanks, Alaska
Ice sculpture in Fairbanks, Alaska

The snowpack is established by October 18, on average, and remains until April 23.

West Yellowstone, Montana

Town in Gallatin County, Montana, United States, adjacent to Yellowstone National Park.

Eagle's store in West Yellowstone, 1939

At the peak of the snowpack, which typically occurs in early March, there are 3.5 – 4 feet of snow on the ground.