United States: Water deficits forecast for CA, CO, FL, PA, ME

21 August 2020

THE BIG PICTURE
The 12-month forecast ending April 2021 indicates deficits throughout the West, Southwest, and Southern Rockies, including exceptional deficits. Deficits are also forecast for parts of the U.S. Northeast and in Florida. The Great Lakes Region can expect surpluses, as can South Dakota and north central Nebraska, pockets of the Northwest, states along the Lower Mississippi River, and the Blue Ridge Mountains Region.

In the western U.S., deficits will be especially intense in the San Francisco Bay Area, Nevada, Utah, the Gila River Watershed in Arizona, and the Pecos River Watershed in New Mexico. In Texas, moderate to exceptional deficits are expected in the west and moderate deficits between Austin and San Antonio. Moderate deficits are also forecast on the Arkansas River through western Kansas and the Canadian River through western Oklahoma and the Texas Panhandle.

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In the Northeast, intense deficits are forecast for western Pennsylvania, the border region of northern New York along the St. Lawrence River, and northwestern Vermont. Deficits of lesser intensity are predicted for Ohio, Maine, New Hampshire, Massachusetts, and Connecticut. In Florida, deficits of varying intensity are expected, and in a few pockets Georgia and Alabama. Deficits are also forecast in Iowa in the central Des Moines River Watershed.

Surpluses will be moderate to extreme in northern Michigan and northeastern Wisconsin, and moderate to severe in a central column from South Dakota into Nebraska. Surpluses of varying intensity are expected in other pockets of the Upper Midwest, western Montana, Idaho, and the Pacific Northwest, though deficits are also forecast in central Oregon and a few small pockets in Washington.

Other areas with a forecast of surplus, primarily moderate, include southern Missouri, southwestern Arkansas, Mississippi, southern Virginia, and pockets of the Carolinas.

Outside the contiguous U.S., surpluses are forecast for much of Hawaii. Alaska can expect deficits from Anchorage past Valdez, on the Seward Peninsula, and in the northeast. Surpluses are forecast west of Bethel, north of Iliamna Lake, in the center of the state, and pockets in the southeast. In Puerto Rico, moderate deficits are expected in the west.

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

From August through October the overall forecast indicates that widespread prior surpluses from the Lower Mississippi River region through the southern portion of the Ohio River Basin and the Virginias will shrink considerably, leaving normal conditions in many areas. Moderate to severe surpluses will persist in much of Mississippi and into southeastern Louisiana. A column of surplus will persist from South Dakota into Nebraska. Surpluses are also forecast in pockets of North Dakota, and in northwestern Minnesota, northern Wisconsin, and northern Michigan. Western Montana can expect surpluses of varying intensity and pockets are forecast in Idaho and the Pacific Northwest. Moderate surpluses will increase in a belt across Arizona; exceptional surpluses will persist in the southeast.

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Deficits in the Southern Rockies and the Southwest will shrink and downgrade considerably but will persist in Colorado, northern New Mexico, pockets of Utah, southwestern Arizona, and Nevada. Deficits will increase in California, moderate or more intense in the north and the southeast, but generally mild in much of the Central Valley. In the northeastern U.S., deficits will downgrade in some areas but will be extreme to exceptional along New York’s northern border and surrounding Lake Champlain in Vermont, and severe in western Pennsylvania. Other areas of the country with a forecast of deficit include Florida, south central Alabama, north central Iowa, and along the Canadian River in Oklahoma.

From November 2020 through January 2021, normal water conditions will return to much of the country. Surpluses will persist in northern Michigan, Wisconsin, and northwestern Minnesota; from central South Dakota into Nebraska; western Montana and pockets of Idaho and the Pacific Northwest; and a few isolated pockets in the Southwest. Deficits will shrink and downgrade in Florida and persist in pockets of Colorado and northern Utah.

The forecast for the final months – February through April 2021 – indicates that surpluses will increase in the Great Lakes Region, Upper Midwest, Rockies, and the Pacific Northwest. Some deficits will linger in Florida.

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

IMPACTS
Aided by high temperatures, wildfires are raging in northern California. Four people have died and thousands have been evacuated. Overall statewide, 660,000 acres have burned. Currently two major fires - the LNU Lightning Complex in the northern Bay Area and the SCU Lightning Complex north and east of San Jose - account for over half of the scorched acreage. Though the state’s wildfire season is nowhere near over, 2020 has already surpassed 2019 in death and destruction. Air quality in the Bay Area has worsened, putting it on par with regions of India and China generally thought to have the worst air quality in the world.

As temperatures soared in California, reaching 130F (54.4C) in Death Valley, the state’s grid operator ordered blackouts for up to 3.3 million people to reduce strained power demand. Preserving power stock necessitated the controlled blackouts, but changes in regulations may also be at play. The blackout order is the first in the state in nearly 20 years.

A massive derecho hit the US Midwest in August, doing most of its damage in Iowa. Grain elevators were flattened, cornfields shredded, and power disrupted to more than a million homes in Iowa, Illinois, and Indiana. A federal disaster declaration was approved for Iowa, opening up aid dollars. The Iowa corn crop was in its final stage of growth and a bumper crop was predicted. Crop insurance and a USDA indemnity program will help recover costs of sown fields but farmers who lost binned grain will have to rely on private insurance since there is no federal program for stored losses.

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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