Exceptional deficit conditions are forecast to persist in northern California and the Pacific Northwest. Surpluses may begin to appear in southern California in December. Exceptional surpluses are forecast for a broad swath of the Southwest, Texas, northwestern Mexico, and in the US Central Plains and Midwest.

The first map below depicts the 12-month period May 2015 - April 2016, using observed temperature and precipitation data through July 2015, and forecasts issued the last week of July 2015. As we’ve reported previously, the continental United States is forecast to experience numerous regionally significant water anomalies, with little change in the forecast.

  • Drought is forecast to persist in northern California, though some areas may have both water deficits and surpluses;
  • Exceptional drought may persist in the Pacific Northwest;
  • Severe water deficits are forecast for Minnesota;
  • Exceptional water surpluses are forecast for much of Texas, and along the Red River, the Arkansas River, the Rio Grande River, and in western Nebraska; surpluses are also forecast in the surrounding states of Oklahoma, Missouri, Kansas, Colorado, New Mexico, and Arizona;
  • A wide belt of moderate to exceptional surpluses is expected from the Central Plains eastward;
  • Southeast states are forecast to have characteristics of both water deficits and surpluses.

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.) 

  • Water deficits on the West Coast are likely to persist through October, then moderate beginning in November;
  • The Pacific Northwest may continue to experience deficits through April, but much of California is forecast to transition from deficits to surpluses beginning in December;
  • Surpluses in the Southern and Central Plains are forecast to expand into the US Southwest and northwest Mexico August through April, and may persist in the Midwest through January;
  • The October through January forecast includes 10-20 year water surpluses along the Mississippi River;
  • A broad band of surpluses in the Central Plains may persist and surpluses may continue to emerge and through January to encompass much of the country; 
  • Water deficits in the Southeast may transition to surpluses November through April, with exceptional surpluses forecast for southern Florida January through April.


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.

For more information contact info@isciences.com.

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