The Big Picture
Much of the 12-month map (below) is colored, indicating water conditions other than normal. Water deficits of varying severity are forecast for much of the Northeast, parts of the Southeast, Upper Midwest, and West. Moderate to exceptional water deficits are clearly evident in the West, particularly in southern California from Los Angeles to San Diego and in southwestern Oregon. Deficits of equal severity are also apparent in southern Pennsylvania, Long Island, and a few other pockets. A vast portion of Texas draws our attention to a forecast of moderate to exceptional water surpluses.

Successive and record-breaking rainfalls have caused major flooding along dozens of Texas rivers across a wide area of the state, wreaking havoc in many riverside communities. These "rain bombs," as local meteorologists have dubbed them, have affected East Texas, Dallas and Corpus Christi, Austin, San Antonio, and most severely, Washington County in southeastern Texas, prompting the governor to declare a state of disaster in 31 counties. The Brazos River reached its highest level in a century. Flooding killed at least six people, forced the evacuation of many including 2,600 inmates from two prisons, damaged hundreds of buildings, and washed out a bridge. Nine soldiers died when an Army truck overturned in flooding at Fort Hood.

Forecast Breakdown
The 3-month maps (below) show the evolving conditions in more detail. The persistence of water deficits in the Northeast and the widespread emergence of deficits in the West are evident in the June through August forecast map. Deficits are also forecast to emerge in Illinois, Indiana, Ohio, Michigan, and Wisconsin, with greatest severity in Michigan’s Upper Peninsula. Deficits will persist along the Ohio River and along its southern tributary, the Big Sandy River in eastern Kentucky, and in Tennessee. Deficits will continue to emerge across the Upper Midwest during this period, with particular severity along the Missouri and Yellowstone Rivers.

Widespread moderate (5 to 10 year expected frequency of occurrence) to exceptional (greater than 40 years) deficits are in the forecast for western states from the Pacific Northwest to western Arizona from June through August.

Exceptional water surpluses are forecast to continue to emerge across central and eastern Texas, with surpluses of lesser severity forecast eastward into Louisiana and northward through Nebraska and western Iowa. Moderate surpluses are forecast to emerge in southeastern Virginia.

From September through November aforementioned widespread deficits are forecast to diminish in extent and severity, with the exception of the Missouri and Yellowstone Rivers. Likewise, surpluses from Nebraska through Texas will diminish somewhat, with the exception of a large pocket in the center of Texas near Abilene.

The forecast for the final quarter of the forecast period (Dec 2016-Feb 2017) shows the Upper Midwest and the Southeast in mild water deficit conditions, and a vast portion of the Mississippi Valley in conditions of moderate to severe surplus.

Outside the contiguous US, moderate to extreme deficits are forecast for much of Alaska June through August. Moderate to exceptional surpluses are forecast for the island of Hawaii, particularly in the western half. Moderate deficits are forecast for western Puerto Rico.

(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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