United States: Widespread water surpluses to persist WI to TX

8 February 2019

THE BIG PICTURE
The 12-month forecast ending September 2019 indicates water surpluses in central and eastern Texas reaching north through Oklahoma, Kansas, Iowa, southern Minnesota, and southern Wisconsin. Surpluses are expected to be extreme to exceptional in the heart of Texas, encompassing the Edwards Plateau, and around Austin. In the US East, surpluses are expected from southern New York through western North Carolina and into north-central South Carolina and pockets of western Georgia, with conditions of both deficit and surplus in parts of the Southeast. Surpluses may reach extreme or exceptional intensity in western North Carolina and southern Virginia. Moderate surpluses are forecast on the New River in West Virginia.

Except for the Ohio River Basin where conditions will be relatively normal, deficits will dapple many other parts of the country. Primarily moderate deficits are forecast from southern Michigan through Illinois, Indiana, and the southern Mississippi Basin to the Gulf, though deficits may be severe in southwestern Mississippi and across its western border into Louisiana. Deficits are also forecast in the West, Pacific Northwest, Rocky Mountain States, and Northern Plains States. These deficits are expected to be severe in western Colorado, extreme in western Oregon and northwestern Montana, and exceptional in northwestern Wyoming and southeastern Washington at the confluence of the Columbia and Yakima Rivers.

On the opposite side of the country, moderate deficits are forecast for Maine’s northern half. Deficits in southern Florida are expected to be moderate to severe but may be exceptional in a small pocket of the northern Everglades.

Outside the contiguous US, moderate to severe deficits are forecast for Puerto Rico. In Hawaii, surpluses are forecast for western Hawai’i and western Moloka’i, and moderate deficits on Maui.

In Alaska, surpluses are forecast on the Alaska Peninsula reaching inland; southeast of Barrow in the far north; and along the Koyukok and central Yukon Rivers. Deficits are expected in the Seward Peninsula and into western Alaska; along the Tanana River through Fairbanks; around Anchorage; and around Sitka in the Alaska Panhandle.

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

The extent of exceptional surpluses is forecast to diminish from January through March, but widespread and intense conditions will persist in the center of the country while surpluses in the East shrink and moderate. Intense surpluses will continue to cut a broad path from Wisconsin through southern Minnesota, Iowa, eastern Nebraska, eastern Kansas, central Oklahoma, and central and eastern Texas. Anomalies will be exceptional in southern Minnesota into northern Iowa, pockets of northern Nebraska, central Kansas, and from the heart of Texas past the Oklahoma border. Moderate surpluses are for northern Michigan. In the East, surpluses are expected to moderate from Vermont down along the Eastern Seaboard through Florida’s Panhandle.

Deficits are forecast for northern New York, northern Maine, and southern Florida, and may be especially intense in New York. Conditions will be nearly normal from the Ohio River Basin to the Gulf of Mexico.

In the western half of the US, mild deficits are forecast overall punctuated by pockets of more intense anomalies, deficits as well as surpluses. Areas of intense deficit include pockets in northwestern Wyoming, central and northeastern Colorado, and central Montana. Scattered surpluses of varying intensity are forecast in western and southeastern Montana, northern Idaho, Washington, and Wyoming.

From April through June surpluses will nearly disappear in the East transitioning to deficit and will retreat considerably from the center of the country persisting in the heart of Texas with some intensity. Moderate surpluses are forecast along the Brazos River, the Arkansas River, in northeastern Nebraska, and the Salmon River region of Idaho. Moderate to severe deficits will emerge from Michigan through the Ohio River Valley to the Gulf of Mexico, with severe deficits in Pennsylvania, along the Ohio River, along the White and Black Rivers in Arkansas, and along the Lower Mississippi. Moderate deficits are forecast scattered throughout the Northern Plains, Rocky Mountain States, and the West, with pockets of more intense deficit in western Montana and in Washington.

The forecast for the final months – July through September – indicates an overall pattern of deficits, primarily moderate east of the Mississippi, but severe to exceptional in the West, Pacific Northwest, and along major rivers.

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

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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