As we reported last month, the continental United States is forecast to experience numerous regionally significant water anomalies:

  • Exceptional drought will persist in northern California through the Pacific Northwest;
  • Southern California is forecast to have characteristics of both water deficits and surpluses;
  • Exceptional water surpluses are forecast for portions of Texas, Oklahoma, Kansas, Nebraska, Colorado, New Mexico, and Louisiana.

In addition, the current forecast indicates:

WSIM Composite Water Anomaly Index for April 2015 through March 2016

The 3-month composites (below) for the same 12-month period show the evolving conditions in more detail. (It should be noted that forecast skill declines with longer lead times.)

  • Deficits on the West Coast may spread through September, moderate October through December, and then transition to surpluses in California December through March;
  • The region of exceptional surpluses in the Southern and Central Plains is forecast to expand into the US Southwest and northwest Mexico July through March;
  • The October through December forecast includes 10-20 year water surpluses along the Mississippi River;
  • A broad band of surpluses may emerge in the Central Plains July through September and expand from October through March to encompass much of the country;
  • Surpluses are forecast to emerge in the Southeast January through March with exceptional surpluses forecast for southern Florida.

WSIM Composite Water Anomaly Index for April 2015 through March 2016


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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