The snowpack that accumulates during the Northern Hemisphere winter plays a major role in water availability throughout the spring and summer. While we do not report it regularly, WSIM estimates the water content of the snowpack using a metric known as snow water equivalent (SWE). SWE is the amount of water that would be collected if the snowpack melted. The map below shows SWE anomalies expressed in terms of return period as of the end of each month from December 31, 2015 through March 31, 2016. The data for December 31, 2015 are based on observed temperature and precipitation, whereas the others are based on forecasts issues the last week of December 2015.

Observe the large regions of exceptional “snow drought” as of December 31 in the northeast United States, southern Canada, the Italian Alps, and much of Eastern Europe and western Russia. In contrast, there are large snow surpluses in the western US, Central Russia, and Mongolia.

By the end of March, much of the snow surplus in the western US is forecast to transition to deficit, and the deficits in Eastern Europe and western Russia are forecast to persist but moderate a bit in intensity. Extensive snow deficits are forecast to emerge in western Canada, while surpluses in central Russia and Mongolia persist. Exceptional deficit in the Italian Alps are forecast to persist.

Please note that snowpack conditions can change quickly as the result of just one or two storms (or rain on snow events) and are, therefore, hard to forecast. We will continue to monitor the situation as it unfolds over the course of the winter.


Many analyses reported in ISciences-authored blog posts are based on data generated by the ISciences Water Security Indicator Model (WSIM). Other sources, if used, are referenced in footnotes accompanying individual posts. WSIM is a validated capability that produces monthly reports on current and forecast global freshwater surpluses and deficits with lead times of 1-9 months at 0.5°x0.5° resolution. This capability has been in continuous operation since April 2011 and has proven to provide reliable forecasts of emerging water security concerns in that time-frame. WSIM has the ability to assess the impacts of water anomalies on people, agriculture, and electricity generation. Detailed data, customized visualizations, and reports are available for purchase.

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