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Snow Drought

Snowpack typically acts as a natural reservoir, providing water throughout the drier summer months. Lack of snowpack storage, or a shift in timing of snowmelt from that reservoir, can be a challenge for drought planning. Snow drought is a period of abnormally little snowpack for the time of year. Recent research shows that the western U.S. has emerged as a global snow drought “hotspot,” where snow droughts became more prevalent, intensified, and lengthened in the second half of the period 1980 to 2018.

View Latest Snow Drought Update

Types of Snow Drought

There are two types of snow drought based on the AMS Glossary of Meteorology:

A ruler buried in snow
Dry snow drought

Below-normal cold-season precipitation

A forest with some partially melted patches of snow
Warm snow drought

A lack of snow accumulation despite near-normal precipitation, caused by warm temperatures and precipitation falling as rain rather than snow or unusually early snowmelt.

Data, Maps, and Tools

Few drought metrics include storage and release of snow water. Several years of low snowpack, especially across the western U.S., have led to studies examining the causes and impacts of reduced snow storage and seeking a new definition for snow drought.

Snow Drought Conditons

This USDA Natural Resources Conservation Service (NRCS) map shows Snow Telemetry (SNOTEL) snow water equivalent (SWE) basin values over the western U.S. as a percent of the NRCS 1981–2010 median. Only stations with at least 20-years of data are included in the station averages.

The SWE percent of normal represents the current snow water equivalent found at selected SNOTEL sites in or near the basin compared to the average value for those sites on this day. This map is valid as of January 19, 2021.

Learn more.

This map shows SNODAS snow water equivalent (SWE) values as a percent of normal. The SNOw Data Assimilation System (SNODAS) is a modeling and data assimilation system developed by NOAA's National Operational Hydrologic Remote Sensing Center (NOHRSC) to provide the best possible estimates of snow cover and associated parameters to support hydrologic modeling and analysis. Learn more.

Snow Water Equivalent (SWE) Percent of NRCS 1981–2010 Median

The color with the hex code #0400ed identifies:
≥ 200%
The color with the hex code #0d6c88 identifies:
175%
The color with the hex code #19dc1e identifies:
150%
The color with the hex code #8feb94 identifies:
125%
The color with the hex code #fefefe identifies:
100%

The color with the hex code #ffd081 identifies:
75%
The color with the hex code #ffa200 identifies:
50%
The color with the hex code #ea5302 identifies:
25%
The color with the hex code #d60000 identifies:
≤ 0%
The color with the hex code #767676 identifies:
No value

SWE Percent of Normal (%)

The color with the hex code #543005 identifies:
0 – 5
The color with the hex code #8c510a identifies:
5 – 25
The color with the hex code #bf812d identifies:
25 – 50
The color with the hex code #dfc27d identifies:
50 – 70
The color with the hex code #f6e8c3 identifies:
70 – 90
The color with the hex code #f5f5f5 identifies:
90 – 110

The color with the hex code #c7eae5 identifies:
110 – 130
The color with the hex code #80cdc1 identifies:
130 – 150
The color with the hex code #35978f identifies:
150 – 200
The color with the hex code #01665e identifies:
200 – 400
The color with the hex code #003c30 identifies:
400 – 800
Source(s):

USDA NRCS

Source(s):

NOAA

Last Updated  -  01/19/21
Updates Daily  -  01/19/21

Impacts and Related Content

Summer Water Availability

Snow droughts reduce the amount of available water for spring and summer snow melt. This, in turn, reduces or shifts the timing of streamflow and reduces soil moisture, which can have impacts on water storage, irrigation, fisheries, vegetation, municipal water supplies, and wildfire.

Winter Water Management

Warmer winter storms lead to rain instead of snow at higher elevations in mountain regions. This can create challenges for water management and flood mitigation strategies, particularly when dealing with extreme events.

By Sector | Recreation and Tourism

Many local economies and industries rely on snowpack and river flows from snowmelt to support their outdoor industries, such as skiing, rafting, and fishing.

Research & Learn | Snow Drought

Find more detailed information about snow drought, including the importance of snowpack and snow drought’s impact on ecosystems, water supply, and local economies.

The Great Western Snow Drought of 2015

The winter of 2015 brought unusually warm temperatures to the western United States and serves as a classic example of how warm temperatures can cause snow drought. By April 1, not a single basin in the West was above 86% of median snow water equivalent—and most basins in Washington, Oregon, California, Nevada, Utah, and Arizona were below 40%.

The Rocky Mountains covered in snow and trees

Snow Drought Research and Resources