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Snowpack Melting Earlier and/or Faster

Temperature directly influences mountain snowpack, which provides natural storage of precipitation during cold winter months until it melts and provides water in the form of runoff as temperatures warm. Over the past few decades, warming temperatures have been linked to changes in the percentage of precipitation falling as rain or snow, and snow melt anomalies showing a trend towards earlier and faster stream flow.

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US trends

Annual trends toward earlier spring melt and reduced snowpack are already affecting water resources in the western United States.[1]

A May 2011 study based on observational data finds that temperature affects snowpack in the mid to late portion of the snow season (March through May), but it did not identify an influence during the earliest phase (February), when temperatures are generally well below freezing.[2] The mid- to late snow season is precisely when significant loss of snowpack is seen at nearly all locations over the past few decades, both through decreases in snow accumulation and increases in snow melt.[2] 

Spring snow melt can play a role in stream flow. The number of days with high stream flow (the top 25 percent of readings) has risen over the past 30 years in the largest rivers of the US, including the Ohio, Missouri, and Mississippi.[3] During the spring, some of largest increases in high stream flow days are in Upper Mississippi River Valley and the Northwest.[3]

The influence of spring temperature is particularly pronounced in years that experience low snowpack accumulations, indicating the potential importance of the albedo feedback[4] for the melting of shallow snow.[5]

Select a pillar to filter signals

Air Mass Temperature Increase
Arctic Amplification
Extreme Heat and Heat Waves
Glacier and Ice Sheet Melt
Global Warming
Greenhouse Gas Emissions
Land Ice and Snow Cover Decline
Land Surface Temperature Increase
Permafrost Thaw
Precipitation Falls as Rain Instead of Snow
Sea Ice Decline
Sea Surface Temperature Increase
Season Creep/ Phenology Change
Snowpack Decline
Snowpack Melting Earlier and/or Faster
Atmospheric Moisture Increase
Extreme Precipitation Increase
Runoff and Flood Risk Increase
Total Precipitation Increase
Atmospheric Blocking Increase
Atmospheric River Change
Extreme El Niño Frequency Increase
Gulf Stream System Weakening
Hadley Cell Expansion
Large Scale Global Circulation Change/ Dynamical Changes
North Atlantic Surface Temperature Decrease
Ocean Acidification Increase
Southwestern US Precipitation Decrease
Surface Ozone Change
Surface Wind Speed Change
Drought Risk Increase
Land Surface Drying Increase
Intense Atlantic Hurricane Frequency Increase
Intense Cyclone, Hurricane, Typhoon Frequency Increase
Intense Northwest Pacific Typhoon Frequency Increase
Tropical Cyclone Steering Change
Wildfire Risk Increase
Coastal Flooding Increase
Sea Level Rise
Air Mass Temperature Increase
Storm Surge Increase
Thermal Expansion of the Ocean
Winter Storm Risk Increase
Coral Bleaching Increase
Habitat Shift or Decline
Parasite, Bacteria and Virus Population Increase
Pine Beetle Outbreaks
Heat-Related Illness Increase
Infectious Gastrointestinal Disease Risk Increase
Respiratory Disease Risk Increase
Vector-Borne Disease Risk Increase
Storm Intensity Increase
Tornado Risk Increase
Wind Damage Risk Increase
What are Climate Signals?