United States: Exceptional water deficits forecast in the Northeast, surpluses in eastern Texas

The Big Picture
The 12-month map (below) indicates that water deficits ranging from moderate (5 to 10 years expected frequency) to extreme (20 to 40 years) with isolated instances of exceptional severity (greater than 40 years) are forecast for: the US Northeast, Tennessee, northern Alabama, northwestern Georgia, the eastern portion of Michigan’s Upper Peninsula, Montana, northern Wyoming, northeastern Utah, parts of the Pacific Northwest and California. Primarily moderate deficits are forecast in Michigan, Illinois, Indiana, Ohio, and in the Upper Midwest. Surpluses are forecast in eastern Texas, northern Wisconsin, Nebraska, and northeastern Nevada.

Impacts
June flooding in West Virginia killed at least 23 people, toppled power lines, washed out roads and lifted houses from their foundations. The torrential storms brought staggering rainfall totals: The National Weather service said that 24-hour rainfall amounts in parts of Fayette, Nicholas, and Greenbrier Counties were a “thousand-year event.” Nearly 500 people were stranded inside a mall for 24 hours when rain washed out an access road. A state of emergency was declared in 44 counties.

Nine wildfires burned in California, destroying nearly 70,000 acres, engaging 5,000 firefighters, and killing two people. A heat wave that sent temperatures into triple digits, bark beetle infestation which desiccated trees, and drought were all cited as contributing to conditions leading to the fires.

According to a recent report by NOAA's National Centers for Environmental Information, the US has experienced eight weather or climate-related disasters in the first six months of 2016 that have each met or exceeded $1 billion in damages, well above the average number of billion-dollar events compared with past years.

Forecast Breakdown
The 3-month maps (below) show the evolving conditions in more detail. The persistence of extreme to exceptional water deficits in the Northeast is evident in the July through September forecast. Deficits are also forecast to emerge in Illinois, Indiana, Ohio, and Michigan with greatest severity in Michigan’s eastern Upper Peninsula. Deficits will persist in Tennessee, and continue to emerge nearby in Alabama, Georgia, South Carolina, and southern Virginia. Deficits will also continue to emerge across the Upper Midwest during this period, with particular severity along the Missouri and Yellowstone Rivers.

Widespread moderate to exceptional deficits are in the forecast for the Pacific Northwest and California’s southern half from July through September. Both deficits and surpluses may emerge in some areas.

Moderate to exceptional water surpluses are forecast to continue to emerge across central and eastern Texas July through September. Surpluses are also forecast for West Virginia and Nebraska.

From October through December aforementioned widespread deficits are forecast to diminish in extent and severity with the exception of the Missouri and Yellowstone Rivers. Surpluses in Texas will diminish considerably, surpluses in Nebraska and northeastern Nevada will persist, and widespread surpluses are forecast to emerge in Wisconsin and across the Mississippi River into Minnesota.

The final quarter of the forecast period (Jan-Mar 2017) indicates water surpluses in many parts of the country which may be especially widespread in Wisconsin and Minnesota.

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

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