The 12-month map ending June 2016 for the contiguous United States (below) indicates water deficits in the Northwest and eastward through the Great Lakes region; moderate surpluses in California and Virginia; moderate to exceptional surpluses in the Central and Southern Plains; and, moderate to exceptional deficits in southern Arkansas, Louisiana, and Mississippi, with central Louisiana experiencing both deficits and surpluses. The map is based on observed data through September 2015 and forecasts issued the last week of September 2015.

In September California's Valley Fire burned 70,000 acres, destroyed 585 homes, and forced nearly 13,000 people to evacuate, killing one civilian.  With reservoir and stream levels still far below normal, officials in Washington and Oregon are concerned about continuing water deficits.

The 3-month composites (below) for the same 12-month period show the evolving conditions in more detail.

Deficits may diminish but persist in the US Northwest for a few months before transitioning to moderate surpluses January through March, after which water deficits may emerge again. California and other western states may also transition to surpluses but these areas are forecast to remain in surplus conditions through the remainder of the forecast period. Also notable in the January through March forecast are widespread surpluses in the Central and Southern Plains, and along the entire East Coast from Maine to Florida. As seen in the April through June map, some surpluses may persist in the West, as previously mentioned, and in Texas, Oklahoma, Kansas, Colorado, New Mexico, Florida, and South Carolina.

In contrast, extensive deficits are expected to emerge April through June from the central Gulf Coast region northward through the Great Lakes Region, with exceptional deficits forecast for Wisconsin and Michigan.

(It should be noted that forecast skill declines with longer lead times.)


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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