United States: Water deficits forecast across the North, Mississippi Valley; surpluses in Texas, South Carolina

The 12-month map ending August 2016 (below) shows a forecast of water deficits across the northern US from eastern Oregon to Maine, with greatest severity in the Great Lakes Region. Widespread and severe deficits are also forecast in the Mississippi Valley from Minnesota to the Gulf of Mexico. Surpluses are forecast in California, the Southern Plains, and in the Southeast. Both deficits and surpluses are expected in Virginia, North Carolina, South Carolina, and East Texas.

The 3-month maps (below) for the same time period show the evolving conditions.

Water surpluses manifested as storms across the Southern Plains in late November, causing icy roads and flooding in North Texas, Arkansas, Oklahoma, and Kansas that resulted in at least 14 deaths. A state of emergency was declared in Oklahoma where ice storms cut power to 78,000 users. In the Pacific Northwest surpluses on the Snoqualmie River in Western Washington reached severe flood stage in early December causing landslides and temporarily halting freight and passenger train service between Seattle and Everett. An unusual outbreak of mosquito-borne Dengue fever in Hawaii has invited speculation that a heavier than normal rainy season may be a contributing factor.

As indicated in 3-month "forecast" maps above surpluses are expected December through February for much of the Eastern seaboard, parts of the Upper Midwest, Texas, and Oklahoma. Deficits are expected in Montana, North Dakota, western Minnesota, eastern Kentucky, and West Virginia. From March through May extensive and severe to exceptional deficits are expected to emerge in the Great Lakes Region, the Ohio and Mississippi River Valleys, the central Gulf Coast, and parts of the Northeast. During this period surpluses are forecast in Florida, throughout the Rockies and in the West. Deficits are forecast to persist in the aforementioned areas through August, and to expand to encompass the Pacific Northwest, Upper Rockies, Midwest, and much of the East Coast. Surpluses are forecast to persist in northern California; along the Pecos River in New Mexico; the Canadian River in the Texas Panhandle and Oklahoma; and in Florida.

Outside the contiguous US, much of southern Alaska is forecast to transition from surplus to deficit June through August; Hawaii from surplus to deficit; and Puerto Rico from deficit to surplus.

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