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Snowpack types

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File:Continental divide on Loveland pass 3654 m.jpg]]

The three main types of snowpack are maritime, intermountain, and continental.

Maritime snowpacks are typically found on the windward side of continents, near oceans. They usually feature warmer winter temperatures that stay around freezing ({{convert|-5|to|5|C|sigfig=1}}) and more precipitation, leading to a snowpack that is over {{convert|3|m|ft|sigfig=1}} deep. Frequent storms deposit snow with a higher snow-water equivalent, often around 10 to 20 percent moisture. Most avalanches occur during or immediately after storms, as weak layers do not persist with warmer temperatures and frequent midwinter rain.{{sfn|Tremper|2018|loc=Maritime—Mountains Bordering Oceans}} Thus, it is typical to ski steep, avalanche prone terrain as soon as 24 to 36 hours after the storm. Many areas with a maritime snowpack receive {{convert|15|to|25|m}} of annual snowfall. Areas with a typically maritime snowpack include the Cascade Range, Coastal Range, western Norway,{{sfn|McClung|Schaerer|2006|p=22}} and the Sierra Nevada.{{cite book |last1=Volken |first1=Martin |last2=Schell |first2=Scott |last3=Wheeler |first3=Margaret |title=Backcountry Skiing: Skills for Ski Touring and Ski Mountaineering |date=2007 |publisher=The Mountaineers Books |isbn=978-1-59485-250-3 |page=98 |url=https://books.google.com/books?id=Yg3WTwZxLhIC&dq=maritime+continental+avalanche&pg=PA98 |language=en}}

Intermountain{{sfn|Tremper|2018|loc=Intermountain—Mountains with an Intermediate Influence of Oceans}} or transitional{{sfn|McClung|Schaerer|2006|p=22}} snowpack is colder and drier than maritime snowpack, usually around {{convert|1.5|to|3|m|ft|sigfig=1}} deep. Temperatures stay colder than maritime climates but warmer than continental climates, around {{convert|-15|to|3|C|sigfig=1}}. Although intermountain snowpacks can feature persistent weak layers, avalanches also occur within storm snow. Unlike in maritime climates, instability lingers for several days to weeks after storms.{{sfn|Tremper|2018|loc=Intermountain—Mountains with an Intermediate Influence of Oceans}} Typical areas for this snowpack include the Wasatch Range, Selkirks, and parts of the Alps.{{sfn|McClung|Schaerer|2006|p=23}}

Continental snowpacks are the coldest and thinnest, featuring snow less than {{convert|1.5|m|ft|sigfig=1}} deep and winter temperatures under {{convert|-10|C|sigfig=1}}. Storms are less frequent and deposit less snow, which is less dense. Faceted snow and depth hoar is the typical weak layer, often covered by hard wind slabs. The instability is very persistent and often leads to higher rates of avalanche fatalities.{{sfn|Tremper|2018|loc=Continental—Mountains Far from the Influence of Oceans}} Areas with a typically continental snowpack include Colorado, the Canadian Rockies, the Brooks Range, and the Pamir Mountains. Because of the persistence of weak layers, forecasting relies much more heavily on snowpit tests to determine stability.{{sfn|McClung|Schaerer|2006|p=22}} In continental climates, avalanches can start on less steep slopes than in intermountain or maritime climates.{{cite book |last1=Tremper |first1=Bruce |title=Avalanche Essentials: A Step-by-Step System for Safety and Survival |date=2013 |publisher=Mountaineers Books |location=Slope steepness of avalanches by climate |isbn=978-1-59485-718-8 |url=https://books.google.com/books?id=ypETCgAAQBAJ&dq=maritime+avalanche+climate&pg=PT66 |language=en}}

Local and regional weather conditions can change the type of snowpack typical for a region, for example a typically maritime region might have a cold and thin early season snowpack that resembles continental type, while even a few feet apart the snowpack depth can vary enough to produce vastly different conditions.{{sfn|Tremper|2018|loc=Avalanche climates}} Elevation also dramatically affects the type of avalanches typically experienced in a particular area.{{sfn|McClung|Schaerer|2006|p=23}}

References

{{reflist}}

  • {{cite book |last1=McClung |first1=David |last2=Schaerer |first2=Peter A. |title=The Avalanche Handbook |date=2006 |publisher=The Mountaineers Books |isbn=978-0-89886-809-8 }}
  • {{cite book |last1=Tremper |first1=Bruce |title=Staying Alive in Avalanche Terrain, 3rd Edition |date=2018 |publisher=Mountaineers Books |isbn=978-1-68051-139-0 |language=en}}

Further reading

  • {{cite journal |last1=Sproles |first1=E. A. |last2=Nolin |first2=A. W. |last3=Rittger |first3=K. |last4=Painter |first4=T. H. |title=Climate change impacts on maritime mountain snowpack in the Oregon Cascades |journal=Hydrology and Earth System Sciences |date=9 July 2013 |volume=17 |issue=7 |pages=2581–2597 |doi=10.5194/hess-17-2581-2013 |doi-access=free |bibcode=2013HESS...17.2581S |url=https://hess.copernicus.org/articles/17/2581/2013/ |language=English |issn=1027-5606}}
  • {{cite journal | last1=Taylor | first1=Susan | last2=Feng | first2=Xiahong | last3=Williams | first3=Mark | last4=McNamara | first4=James | title=How isotopic fractionation of snowmelt affects hydrograph separation | journal=Hydrological Processes | volume=16 | issue=18 | date=2002-12-30 | issn=0885-6087 | doi=10.1002/hyp.1232 | pages=3683–3690 | bibcode=2002HyPr...16.3683T | url=https://onlinelibrary.wiley.com/doi/10.1002/hyp.1232 | access-date=2025-06-08| url-access=subscription }}
  • {{cite journal | last1=Conway | first1=H. | last2=Benedict | first2=R. | title=Infiltration of water into snow | journal=Water Resources Research | volume=30 | issue=3 | date=1994 | issn=0043-1397 | doi=10.1029/93WR03247 | pages=641–649 | bibcode=1994WRR....30..641C | url=https://agupubs.onlinelibrary.wiley.com/doi/10.1029/93WR03247 | access-date=2025-06-08| url-access=subscription }}
  • {{cite journal | last1=Frei | first1=Allan | last2=Lee | first2=ShihYan | title=A comparison of optical-band based snow extent products during spring over North America | journal=Remote Sensing of Environment | volume=114 | issue=9 | date=2010 | doi=10.1016/j.rse.2010.03.015 | pages=1940–1948 | bibcode=2010RSEnv.114.1940F | url=https://linkinghub.elsevier.com/retrieve/pii/S003442571000115X | access-date=2025-06-08| url-access=subscription }}
  • {{cite journal | last1=Scaff | first1=Lucia | last2=Krogh | first2=Sebastian A. | last3=Musselman | first3=Keith | last4=Harpold | first4=Adrian | last5=Li | first5=Yanping | last6=Lillo-Saavedra | first6=Mario | last7=Oyarzún | first7=Ricardo | last8=Rasmussen | first8=Roy | title=The Impacts of Changing Winter Warm Spells on Snow Ablation Over Western North America | journal=Water Resources Research | volume=60 | issue=5 | date=2024 | issn=0043-1397 | doi=10.1029/2023WR034492 | doi-access=free | bibcode=2024WRR....6034492S }}
  • {{cite journal | last1=Zeidler | first1=Antonia | last2=Jamieson | first2=Bruce | title=Refinements of empirical models to forecast the shear strength of persistent weak snow layers | journal=Cold Regions Science and Technology | publisher=Elsevier BV | volume=44 | issue=3 | year=2006 | issn=0165-232X | doi=10.1016/j.coldregions.2005.11.004 | pages=184–193}}
  • [https://arc.lib.montana.edu/snow-science/objects/ISSW2023_O7.04.pdf Proceedings, International Snow Science Workshop, Bend, Oregon, 2023 CRUSTS AND FACETS: A CASE STUDY OF A SEASON WITH DEEP ISSUES NEAR GIRDWOOD, AK Andrew Schauer1*, Aleph Johnston-Bloom2, Adam Smith, Matt McKee3, Jim Kennedy4]
  • {{cite journal | last=Hendrikx | first=J. | title=Understanding Mountain Range Spatial Variability of Surface Hoar | journal=AGU Fall Meeting Abstracts | date=2014 | volume=2014 | bibcode=2014AGUFM.C43D0427H | url=https://ui.adsabs.harvard.edu/abs/2014AGUFM.C43D0427H/abstract | access-date=2025-06-09}}
  • {{cite journal | last1=Datt | first1=Prem | last2=Srivastava | first2=P.K. | last3=Sood | first3=G.K. | last4=Satyawali | first4=P.K. | title=Estimation of equivalent permeability of snowpack using a snowmelt lysimeter at Patsio, northwest Himalaya | journal=Annals of Glaciology | publisher=International Glaciological Society | volume=51 | issue=54 | year=2010 | issn=0260-3055 | doi=10.3189/172756410791386670 | doi-access=free | pages=195–199 | bibcode=2010AnGla..51..195D | url=https://www.cambridge.org/core/services/aop-cambridge-core/content/view/B86A198C58205F283FB54AC5FB857D70/S0260305500261156a.pdf/div-class-title-estimation-of-equivalent-permeability-of-snowpack-using-a-snowmelt-lysimeter-at-patsio-northwest-himalaya-div.pdf | access-date=2025-06-09}}
  • {{cite journal | last1=Raleigh | first1=Mark S. | last2=Small | first2=Eric E. | title=Snowpack density modeling is the primary source of uncertainty when mapping basin-wide SWE with lidar | journal=Geophysical Research Letters | volume=44 | issue=8 | date=2017-04-28 | issn=0094-8276 | doi=10.1002/2016GL071999 | doi-access=free | pages=3700–3709 | bibcode=2017GeoRL..44.3700R }}
  • {{cite journal | last1=Birkeland | first1=Karl W. | last2=Mock | first2=Cary J. | title=The Major Snow Avalanche Cycle of February 1986 in the Western United States | journal=Natural Hazards | volume=24 | issue=1 | date=2001 | doi=10.1023/A:1011192619039 | pages=75–95 | bibcode=2001NatHa..24...75B | url=http://link.springer.com/10.1023/A:1011192619039 | access-date=2025-06-09| url-access=subscription }}

Category:Snow