United States: Intense water deficits to persist in CO & UT

22 June 2020

THE BIG PICTURE
The 12-month forecast ending February 2021 indicates water surpluses of varying intensity in a vast block from the southeastern corner of Kansas into the lower Ohio River Basin and well into the Deep South. Surpluses will be exceptional in Tennessee and pockets of Kentucky, Arkansas, Mississippi, Alabama, and Georgia.

Intense surpluses are also forecast for the northern half of Michigan’s Lower Peninsula with surpluses of lesser intensity in other parts of the state and in Wisconsin, Illinois, and Ohio.

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Surpluses of varying intensity are forecast for the Dakotas in a checkerboard pattern. Anomalies will be more prevalent in South Dakota where some relatively small areas will reach exceptional intensity, and surpluses will reach into north-central Nebraska. Some pockets of surplus are also forecast for Montana. Scattered pockets of anomalies, surplus and deficit, are forecast in Wyoming, but deficits will be the dominate anomaly in Nevada, Utah, and Colorado, reaching exceptional intensity in pockets of each state. Moderate deficits will reach into north-central New Mexico. Some surpluses are forecast in southeastern Arizona and near Phoenix.

Deficits of varying intensity are forecast in pockets of Northern California and will be extreme in the San Francisco Bay Area. The Pacific Northwest will see deficits in the central regions of Oregon and Washington with some scattered surpluses elsewhere. Deficits are expected in Idaho’s Salmon River Mountains.

Texas can expect some moderate deficits in the northwest region of the state and along the Rio Grande through Amistad Reservoir, while pockets of moderate to severe surplus are forecast in the northeast. Severe deficits are forecast in several large pockets of Florida: the Ocala National Forest and surrounding Lake Okeechobee.

Nearly normal conditions are expected in the U.S. Northeast and Mid-Atlantic with some surpluses in Upstate New York, and deficits from northern Vermont into Maine and in the Delmarva Peninsula.

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 on the Seward Peninsula, from Anchorage past Valdez, east of Fairbanks, and in the far northeast.

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

From June through August, surpluses will shrink and downgrade considerably in the U.S. with nearly normal conditions returning to many parts of the Upper Midwest, Central Plains, and northern Ohio River Basin. However, severe to exceptional anomalies will persist from South Dakota into north-central Nebraska, and though downgrading, surpluses will remain widespread in the South. Anomalies could reach extreme intensity in southern Virginia and the Carolinas but will be primarily moderate in Arkansas and surrounding states, through the Tennessee River region, and in central Georgia. A pocket of moderate surplus is forecast for central Michigan. Small pockets of deficit are forecast for northern Virginia, the Delmarva Peninsula, and scattered across the U.S. Northeast.

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In the West, deficits will diminish slightly from the prior three months. Pockets of moderate to severe deficit are forecast for the Southern Rockies, Nevada, northern and eastern California and the Pacific Northwest. Deficits will be exceptional in Utah, Colorado, and some smaller pockets elsewhere. The Pacific Northwest can also expect some scattered, small pockets of moderate surplus. Surpluses will persist in central and southeastern Arizona and will increase somewhat in southern California from Santa Barbara to the Mexican border.

From September through November, normal water conditions will return to much of the country east of the Rockies. However, severe to exceptional surpluses will persist from South Dakota into Nebraska, and moderate surpluses will emerge from southern Illinois into western Kentucky with mild surpluses in a broad swath through surrounding states. Moderate surpluses will also emerge in northern Minnesota. Moderate deficits will increase on the Canadian River across the Oklahoma/Texas border. In the West, deficits will shrink and downgrade overall, though mild to moderate deficits will increase somewhat in California. Deficits will be intense in northeastern Utah, southwestern Colorado, and the Salmon River Mountains in Idaho. Surpluses will increase slightly in the Pacific Northwest and will persist in central and southeastern Arizona and pockets of southwestern California.

The forecast for the final months – December through February – indicates moderate surpluses in the Ohio River Valley and Upper Midwest and intense surpluses from South Dakota into Nebraska. In the West, some scattered pockets of surplus are forecast and small pockets of persistent deficit in Utah and Colorado.

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

IMPACTS
Severe drought is currently affecting 26 percent of Puerto Rico prompting authorities to announce water rationing, and another 57 percent of the island is experiencing moderate drought according to the U.S. Drought Monitor. Piped water will be shut off for eight hours a day in the northern municipalities of Canovanas and Loiza during which time water trucks will service the regions.

A year and a half after California’s Camp Fire destroyed the town of Paradise and killed 84 people, the state’s utility provider, Pacific Gas & Electric, pleaded guilty to manslaughter acknowledging that its failure to maintain a transmission line started the fire. The company was accessed a $3 million fine in the criminal case.

In Nevada, power utility NV Energy is advising its customers of the possibility of planned black-outs this summer during periods of extreme fire conditions in order to prevent any utility-related wildfires. Fire-risk areas within NV’s service extent include the Nevada side of the Lake Tahoe basin.

Arizona is currently battling several wildfires and the state has already seen three times as much acreage burned this year as during the same period in 2019. May 2020 brought temperatures to Arizona that were 5.5 F (3.5 C) higher than NOAA’s 20th century averages and no measurable rain has falling in Phoenix for two months. The Bush Fire northeast of Phoenix has scorched nearly 65,000 acres as of mid-June and claims the title of the largest currently active fire in the U.S. The Bighorn Fire near Tucson has destroyed almost 16,000 acres and the Magnum Fire on the North Rim of the Grand Canyon has burned 30,000. COVID-19 protocols emphasizing social distancing are forcing fire squads to re-evaluate evacuation and mass sheltering.

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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