The 3-month composites (below) for the same 12-month period show the evolving conditions in more detail. Of particular interest is the possible emergence of extensive deficits forecast March through May from the central Gulf Coast region northward through the Great Lakes region. (It should be noted that forecast skill declines with longer lead times.) 

September to November:

  • Deficits may persist in the western US, though the Pacific Northwest may experience both deficits and surpluses. Deficits may also persist in the Northern Plains and into Minnesota.
  • Surpluses may persist in the Central and Southern Plains and along Mississippi River tributaries; and may emerge in northern Mississippi, northern Alabama, and eastern Tennessee.
  • Deficits in the Southeast may transition to surpluses in November.
  • Deficits may emerge in Upstate New York, Massachusetts, Connecticut, and Rhode Island, but may subside by November.

December through February:

  • California may transition from deficits to surpluses.
  • Surpluses may dominate many parts of the country, with the exception of the Northern Plains, where deficits may persist. Tributaries of the Mississippi River may continue to experience surpluses.

March through May:

  • Widespread deficits are expected to emerge in the Mississippi Valley from the Gulf of Mexico northward into the Canada, and in the Midwest and Great Lakes.
  • Surpluses may continue to emerge in the West, Southwest, and Texas.
  • Surpluses may also persist in the South Atlantic states, with particular severity in southern Florida.


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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