United States: Water deficits will shrink in the West, emerge in ND

20 December 2020

THE BIG PICTURE
The 12-month forecast ending August 2021 indicates widespread water deficits in the southwest quadrant of the continental U.S. Deficits are expected to be exceptional in many pockets, especially in California, Arizona, and New Mexico.

Generally moderate to severe deficits are expected in western regions of Nebraska, Kansas, and Oklahoma. In Texas, normal conditions are forecast for the center and northeastern regions of the state with deficits of varying intensity elsewhere, including exceptional deficits in the western Panhandle and in the state’s southern tip.

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In the Northwest, some pockets of surplus are forecast in Washington, northern Idaho, and western Montana, but deficits are expected in southern Oregon, and with lesser intensity, pockets of Idaho and Wyoming. Surpluses are forecast in a central pocket on the Wyoming/Montana border. Some scattered pockets of surplus are expected in the Upper Midwest/Great Lakes region in Minnesota, central Wisconsin, and the northern reaches of Michigan’s Lower Peninsula, and also along the White River in Arkansas.

Deficits reaching exceptional intensity are forecast in New England, western Pennsylvania, and along the St. Lawrence River in Upstate New York; as well as in the south in Georgia, Florida, southern Alabama, and the Mississippi Delta. In the Mid-Atlantic, surpluses are forecast in Virginia, Maryland, Washington D.C., northern North Carolina, and into Tennessee. Surpluses will be intense south of Richmond and around Chesapeake Bay.

Outside the contiguous U.S., surpluses are forecast for much of Hawaii. Alaska can expect deficits from Anchorage past Valdez; in the northeast; and in pockets of the west. Surpluses are forecast north of Iliamna Lake; some pockets in the center of the state; and in the eastern Alaska Range. Deficits are expected in western Puerto Rico.

FORECAST BREAKDOWN
The 3-month maps (below) show the evolving conditions in more detail.

Through February 2021, widespread intense deficits in the West will shrink and downgrade considerably, as will widespread surpluses from the Lower Mississippi region to the Atlantic Coast. Intense deficits will persist in Colorado and pockets of Wyoming, Arizona, New Mexico, and Nebraska and will increase in Kansas. Deficits will downgrade in West Texas but increase across much of the rest of the state with severe deficits west of San Antonio and in the Panhandle. In the northern U.S., widespread exceptional deficits will emerge in North Dakota. Scattered surpluses are forecast from Washington through central Montana and along the Missouri River in Montana. Surpluses will increase in northern Minnesota and Wisconsin and intensify in Michigan’s Upper Peninsula.

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Moderate surpluses will emerge in northern Ohio and parts of the U.S. Northeast, particularly New York, as deficits retreat, persisting in a few pockets. Surpluses in the Mid-Atlantic will shrink and moderate. In the Southeast, surpluses will retreat, and deficits will increase in Alabama and Georgia. Deficits will increase in Florida, emerging in the Panhandle as surpluses retreat. Deficits will persist in northern Florida and around Lake Okeechobee in the south; surpluses are forecast along Florida’s southern coast. In Louisiana, intense deficits will persist around Lake Pontchartrain.

From March through May 2021, normal water conditions will return to many regions. However, deficits will persist in the southern Rockies and Southwest, with pockets of exceptional deficit particularly widespread in New Mexico. Surpluses will emerge in southern Arkansas, but will shrink considerably elsewhere in the nation, leaving some small pockets in the northern Rockies and Great Lakes. Deficits will increase in the Southeast from Virginia through Florida, with intense deficits in coastal Georgia and South Carolina. Deficits around Lake Pontchartrain will downgrade.

The forecast for the final months – June through August 2021 – indicates deficits in the Southeast, Mississippi Delta, central California, pockets in the Southwest and southern Rockies, and along the Arkansas and Canadian Rivers.

Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
Experts say that 2020 is likely to be a record breaking year for the number of U.S. weather disasters topping a billion dollars each, driven by wildfires, hurricanes, and the Midwest derecho. Though the yearly average is 6.6 such events, forecasters estimate 20 this year, making it the sixth year in a row with 10 or more billion-dollar climate and weather disasters.

Drought has plagued much of the U.S. West since spring with extreme to exceptional drought in the Southwest. Nearly 50 percent of New Mexico is under exceptional drought. Cattle ranchers in the region are struggling to keep supplemental feed costs down as grazing land withers with some resorting to massive stock culling and its associated long-term negative financial impacts. State water managers have begun pumping water from reservoirs to alleviate water shortfalls in the Pecos River. Complicating water preservation efforts, nearly 200 dams in the state have been rated “poor” by the U.S. Army Corp of Engineers.

By the end of November, all of Arizona was classified in drought conditions with a third of the state experiencing exceptional drought. The Arizona State Game and Fish Department has been hauling water to wildlife areas since June to prevent disease transmission from domesticated to wild animals who may otherwise venture farther for water supplies. Rainfed corn crops in Hopi tribal lands have withered this year and long-term aridification threatens the future of native agricultural traditions.

NOTE ON ADMINISTRATIVE BOUNDARIES
There are numerous regions around the world where country borders are contested. ISciences depicts country boundaries on these maps solely to provide some geographic context. The boundaries are nominal, not legal, descriptions of each entity. The use of these boundaries does not imply any judgement on the legal status of any territory, or any endorsement or acceptance of disputed boundaries on the part of ISciences or our data providers.

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