United States: Intense water deficits will shrink in the West & Southwest

19 September 2020

THE BIG PICTURE
The 12-month forecast ending May 2021 indicates widespread water deficits in the southwest quadrant of the continental U.S. from Wyoming through West Texas and reaching west through California. Deficits will be exceptional in many areas including nearly all of Arizona and large blocks in New Mexico, Utah, and as far north as western Nebraska. Moderate deficits are forecast in southeastern Texas, and severe deficits on the Canadian River through western Oklahoma.

ISciences_United_States_Composite_Adjusted_202006-202105_12mo_twitter.png

The Pacific Northwest can expect deficits in central Oregon and mixed conditions in Washington and northern Idaho. Pockets of surplus are forecast for western Montana.

In the Upper Midwest, surpluses are expected across the central border of South Dakota into Nebraska, and pockets in northwestern Minnesota. Iowa will see deficits that will be extreme in the middle region of the Des Moines River at the West Fork. Around the Great Lakes, surpluses are forecast for northern Wisconsin and northern Michigan. Some moderate deficits are expected from northern Illinois through Ohio, but deficits will be intense and widespread in western Pennsylvania. Deficits of varying intensity are expected in the U.S. Northeast with exceptional deficits in the St. Lawrence River region of Upstate New York and pockets in Vermont.

Surpluses are forecast from D.C. to Richmond, Virginia; a few pockets of North Carolina; and in Arkansas. Deficits are expected in much of Florida outside of the Panhandle with extreme deficits northwest of Orlando and exceptional deficits in the central Everglades.

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, from Denali east to the Canadian border, and pockets in the Panhandle.

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

From September through November the overall forecast indicates that surpluses from the Lower Mississippi River through the Virginias will shrink considerably, as will widespread, intense deficits from Wyoming through the U.S. Southwest. Surpluses will persist in Arkansas, pockets to the east and north, and in eastern Virginia. In the U.S. Northeast, deficits will shrink and downgrade somewhat, but intense pockets will persist, particularly in western Pennsylvania. Moderate surpluses will emerge in eastern Pennsylvania and southeastern New York. Deficits in Florida will persist and intensify, and moderate deficits are expected in southern Alabama and southern Georgia. In the Great Lakes Region, surpluses are forecast for northern Minnesota, parts of Wisconsin, and northern Michigan. Deficits will moderate in Iowa and become merely mild through northern Illinois, Indiana, and Ohio. Surpluses will persist from central South Dakota well into central Nebraska.

United_States_Composite_Adjusted_202006-202105_3mo_twitter.png

Deficits in the Southern Rockies and the Southwest will shrink and downgrade though areas of intensity will persist, including Colorado. Deficits in Northern California will moderate, but deficits will emerge in the south and will be intense in some areas including the border with Nevada. Deficits will increase in the Pacific Northwest and northern Idaho, and surpluses will persist in southeastern Idaho and western Montana.

From December 2020 through February 2021, normal water conditions will return to many regions. Surpluses are forecast in the Great Lakes; from central South Dakota into Nebraska; in western Montana and pockets of Idaho and the Pacific Northwest; and a few isolated areas in the Southwest. Deficits will shrink and downgrade in Florida and persist in central Colorado and northern Utah.

The forecast for the final months – March through May 2021 – indicates nearly normal conditions from the Great Plains to the East Coast, some surpluses in Minnesota and in the northern Rocky Mountains, and deficits in the Southwest and Southern California. Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
The record-breaking 2020 Atlantic hurricane season has produced 20 named storms in a little over three months compared to the seasonal average of 12 storms from June 1 through November 30.

Hurricane Laura struck the southeastern U.S. in late August, with Category 4 intensity that killed at least 27 people in Louisiana according to the state’s department of health. Many of the deaths resulted from carbon monoxide poisoning from faulty generators and heat-related illness. The storm knocked out power to 800,000 homes, triggered a fire in a chemical plant that impacted air quality, and damaged over 70 drinking water systems, taking down a 100,000-gallon water tower.

The Florida Panhandle took the brunt of the damage when Hurricane Sally struck in mid-September, dumping over 30 inches of rain on Pensacola in four hours and taking out a section of the Pensacola Bay Bridge when a barge crashed into it. A half a million people were without power in Florida and Alabama. Initial estimates of the storm’s damage indicate between $2 billion to $3 billion.

Multiple wildfires continue to rage in California and Oregon, fueled by high temperatures, lack of rain, and abundant forest stock. The blazes left apocalyptic scenes as they devoured communities, reduced air quality, and blew smoke and particulates into Canada, through the U.S. Midwest, to the East Coast, and even reaching Europe. In California, 3.2 million acres has burned since the start of the year. At least 24 people have died in the recent spate of 28 fires. The 12 wildfires burning in Oregon have destroyed 938,000 acres, leveling many small towns.

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.

Subscribe to our monthly Water Watch List

Search blog categories

Search blog tags