United States: Water deficits forecast for the Northeast

24 July 2020

THE BIG PICTURE
The 12-month forecast ending March 2021 indicates moderate water surpluses in the lower Ohio River Basin and into the Deep South and lower Mississippi River region. Surpluses will be more intense in some pockets including western Virginia, Tennessee’s northeastern corner, central Mississippi, and Arkansas’ southwest quadrant.

Around the Great Lakes, surpluses are forecast for pockets of northern Michigan, Wisconsin, and northeastern Illinois. Surpluses are also expected from southeastern Minnesota into northeastern Iowa.

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In the northern Plains States, severe surpluses are forecast for north-central Nebraska and well into South Dakota, while anomalies of varying intensity are predicted in other pockets of the Dakotas including the Black Hills region. Montana’s western half can expect surpluses of varying intensity.

Some isolated pockets of surplus and of deficit are forecast for Idaho. In Wyoming, deficits will reach extreme intensity east of Casper, but surpluses are expected in the south-central region of the state. Deficits are predicted throughout most of Utah and Colorado and will be exceptional in some areas. Deficits of varying intensity will reach into northern and eastern New Mexico, the panhandles of Texas and Oklahoma, and will follow the path of the Arkansas River through western Kansas. Moderate surpluses are forecast from eastern Oklahoma into Texas, and moderate deficits east of San Antonio. Some surpluses are forecast in southeastern Arizona and near Phoenix.

In Northern California, intense deficits will lead from San Francisco to Sacramento, downgrading as they reach further north. Deficits will also be intense near the Oregon border and from Lake Tahoe into western Nevada. Surpluses are expected in northeastern Nevada and west of Las Vegas, and a small pocket of surplus is forecast near San Diego, California. In the Pacific Northwest, deficits are forecast for a large part of central Oregon and some small pockets down the center of Washington, with scattered surpluses elsewhere in the region.

Deficits of varying intensity are forecast in pockets of U.S. Northeast and will be widespread in Maine. Western Pennsylvania can expect severe deficits. Surpluses are forecast in parts of Virginia, the Carolinas, and in central Georgia. Moderate deficits are forecast in Florida from Jacksonville to Orlando, a few isolated pockets in the panhandle, and north of Lake Okeechobee. Deficits south of the lake will be severe.

Outside the contiguous U.S., surpluses are forecast for much of Hawaii. Alaska can expect surpluses from the base of the Alaska Peninsula leading inland to the center of the state and in the southwest near Bethel. Deficits are forecast from Anchorage past Valdez, east of Fairbanks, on the Seward Peninsula, and in the far northeast of the state. In Puerto Rico, moderate deficits are forecast.

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

From July through September the overall forecast indicates that surpluses will shrink and downgrade considerably in the South, Southeast, and Upper Midwest; deficits will shrink and downgrade in the Rockies and Southwest; and deficits will increase in the Northeast.

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In the South and Southeast, pockets of surplus will persist, with greatest extent in Arkansas, Mississippi, southern Virginia, and the Carolinas. Surpluses will be severe to extreme in Mississippi. Deficits will shrink and moderate in Florida. In the Great Lakes Region, nearly normal conditions will return to Michigan, Wisconsin, and Illinois though some mild deficits will emerge. Some pockets of moderate deficit will emerge in the northern portion of the Ohio River Basin, and deficits will increase from Pennsylvania through the Northeast and will include intense anomalies.

Deficits in northern Minnesota will shrink and moderate. Surpluses will persist in north-central Nebraska and into South Dakota, pockets of North Dakota, and in western Montana. Though deficits will shrink and downgrade in Wyoming, Nevada, Utah, and Colorado, and retreat considerably from New Mexico, some intense pockets will persist.

In California, deficits of varying intensity will persist in the north, diminishing slightly, and surpluses will persist in the southwest. The Pacific Northwest can expect both surpluses and deficits.

From October through December, normal water conditions will return to much of the country. Some pockets of deficit will persist in the Northeast, particularly in Maine. Surpluses will persist in north-central Nebraska, central South Dakota, and pockets of North Dakota and northwestern Minnesota. Surpluses will also persist in western Montana, increasing slightly across the border into Idaho. Deficits will nearly disappear in the West, persisting with intensity in northern Utah and a small pocket in south-central Colorado. Pockets of surplus will persist in the Pacific Northwest, northeastern and southern Nevada, north of San Diego, and southeastern Arizona and near Phoenix. Some moderate deficits will persist along the Canadian River through western Oklahoma and south of New Orleans, Louisiana.

The forecast for the final months – January through March 2021 – indicates nearly normal conditions in the southern half of the U.S. and surpluses in many parts of the northern half, particularly the Upper Midwest, northern Plains States, and northern Rockies. Surpluses will emerge on the Missouri and North Platte Rivers and persist from central South Dakota into north-central Nebraska.

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

IMPACTS
Much of the US Northeast from New York through Maine received a quarter to half the normal rainfall during May and June.

Nearly half of Maine was experiencing some level of drought. About 45 percent of the state’s residents depend on well water and some wells are already running dry. As water tables drop, officials warn that water conservation is likely the only option for owners of private wells, since once dry, wells won’t replenish until fall.

New Mexico’s chile farmers are facing drought conditions. Low flows from the Rio Grande are forcing farmers to pump more water. Production has also been hampered by the coronovirus pandemic and worker shortages.

Storms in early July left the streets of Grand Forks, North Dakota flooded after six inches of rain fell, threatening some motorists while delighting a few adventurous kayakers. Storms have been soaking the region since early June, prompting county officials to announce an Emergency Disaster Declaration, with damages estimated at between $458,000 to $1 million.

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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