United States: Widespread water surpluses WI to TX & NY to GA
18 December 2018
THE BIG PICTURE
The 12-month forecast ending August 2019 indicates significant blocks of water surplus in three regions: the East Coast from southern New Hampshire through North Carolina; much of Texas into Oklahoma and Kansas; and Iowa and southern Wisconsin. Surpluses are expected to be extreme to exceptional in the heart of Texas surrounding the Edwards Plateau, eastern Pennsylvania, and coastal North Carolina around Wilmington.
With the exception of the Ohio River Basin where conditions will be relatively normal, deficits will dapple much of the rest of the country though anomalies will be primarily mild to moderate. Pockets of deficit are forecast for the Upper Midwest, Rocky Mountain States, and the West. Deficits may reach severe intensity in western Oregon; and severe to extreme intensity in northwestern Wyoming, the western Uinta Mountains of northeastern Utah, and central and southeastern Colorado. Generally moderate deficits are forecast for much of Minnesota, pockets of Michigan, central Illinois, southern Missouri, eastern Louisiana, Mississippi, and Alabama. In the US Northeast, deficits will be moderate to exceptional in northern New York, and moderate in Vermont, central New Hampshire, and Maine. Deficits in southern Florida are expected to be moderate to severe but may be exceptional in a small pocket of the northern Everglades.
A patchwork of conditions is forecast for Alaska including: surpluses on the Alaska Peninsula reaching inland, the upper reaches of the Copper and Susitna Rivers, and in the far north southeast of Barrow; and, deficits in the Seward Peninsula and into western Alaska, around Anchorage, and the Alexander Archipelago in the Alaska Panhandle.
The 3-month maps (below) show the evolving conditions in more detail.
Though the extent of exceptional surpluses is forecast to shrink from December through February, widespread and intense surpluses will persist in the center of the country and in the east. Intense surpluses will continue to cut a broad path from Michigan’s Upper Peninsula through Wisconsin, southern Minnesota, Iowa, northern Missouri, eastern Kansas, central Oklahoma and central and eastern Texas, with anomalies of exceptional intensity along much of that path. Moderate surpluses are forecast for Michigan’s Lower Peninsula and the northern Ohio River Basin, leading to widespread surpluses in the east from southern New York and Massachusetts down along the Eastern Seaboard through Florida’s Panhandle. Surpluses are expected to reach extreme intensity in eastern Pennsylvania and nearby regions in neighboring states.
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 southern 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. Conditions in California are expected to be relatively normal. Severe to exceptional deficits are forecast for northwestern Wyoming, and moderate to extreme deficits in Colorado, north-central Utah, and western Oregon. Intense surpluses are forecast for northern Nebraska, a patch south of the Black Hills on the Wyoming-South Dakota border, southeastern Montana, and between Great Falls, Helena, and Billings, Montana.
From March through May, widespread surpluses forecast for the eastern half of the country in prior months will nearly disappear, and moderate deficits will emerge from Michigan through the Ohio River Valley to the Gulf, and also in the Northeast. Surpluses will persist in Texas and Oklahoma but will downgrade, though pockets of exceptional surplus are possible in Texas. Central Colorado will transition from deficit to surplus, as will the Arkansas and Canadian Rivers. Both deficits and surpluses are forecast for northwestern Wyoming as deficits emerge in the north; surpluses will emerge in central Idaho but diminish in western Montana; and surpluses will emerge in California and Nevada near Lake Tahoe. Moderate to severe deficits are forecast for parts of the Northern Plains.
The forecast for the final months – June through August – indicates surpluses in Texas, Oklahoma and pockets of southern Florida, and primarily mild to moderate deficits in much of the remainder of the nation. However, deficits are forecast to be more intense in central California and the Pacific Northwest.
(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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