United States: Water deficits include NorCal & Rockies

21 July 2022

THE BIG PICTURE
The 12-month forecast ending March 2023 indicates widespread water deficits of varying intensity in the U.S. West, Rockies, Southwest, and Texas. Deficits are also expected in Florida and several regions on the East Coast. The Central Plains will see deficits, but surpluses are forecast in the Northern Plains as well as parts of the Pacific Northwest.

In the West, exceptional anomalies will be widespread in California’s San Joaquin Valley with deficits of varying intensity in most other regions of the state. Other areas with a forecast of exceptional deficit include southwestern Arizona, the Utah Rockies, and the Salmon River Mountains in Idaho. Though deficits are forecast in many regions of Idaho, Montana, and Wyoming, some isolated pockets of surplus are also forecast.

In the Pacific Northwest, surpluses are expected from western Washington into Oregon and spanning their shared border region in the east.

In the center of the nation, moderate to severe deficits are forecast in Nebraska and Iowa, and moderate deficits in southwestern Missouri and pockets of Kansas. The Northern Plains, however, can expect widespread severe to extreme surpluses from eastern North Dakota into Minnesota and South Dakota. Deficits will follow much of the Missouri River.

The forecast for Texas indicates widespread deficits, extreme to exceptional from the Hill Country into the South Texas Plains. Deficits will also be especially intense southwest of Amarillo in the Panhandle. In Louisiana, moderate deficits are forecast in the southwest and severe deficits at the mouth of the Mississippi.

On the East Coast, moderate to extreme deficits are forecast in eastern Maine, and a few pockets of moderate deficit in Massachusetts. Deficits of varying intensity are forecast in Virginia, North Carolina, pockets of South Carolina and Georgia, and many regions of Peninsular Florida. Surpluses are expected in the Everglades.

Outside the contiguous U.S., Alaska can expect deficits in the northeast and central north, and near Anchorage in the south. Surpluses are expected near Juneau, Nome, west of Bethel, the central region of the Alaska Peninsula, north of Iliamna Lake, and at the eastern end of the Alaska Range. Surpluses are forecast in Hawaii and severe deficits in western Puerto Rico.

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

The forecast through September indicates that, while many regions of the country will see deficits, exceptional anomalies will be limited primarily to pockets in the Rockies and northern California. Mild to moderate deficits are forecast in southern California and deficits of varying intensity in the north. Mixed conditions are expected in the Pacific Northwest: surpluses in the far northwest, Blue Mountains, and northern Idaho, and pockets of deficit elsewhere. Pockets of deficits are expected in the Rockies and Nevada along with some isolated surpluses. Severe to extreme surpluses will remain widespread in the eastern region of the Dakotas and into Minnesota, and surpluses are forecast in a pocket on the Missouri River west of Lake Sakakawea. Deficits, generally moderate are forecast from Nebraska through the Upper Mississippi River Basin, on the Arkansas River, and in East Texas and southern Louisiana. Moderate surpluses will emerge on the Canadian River. On the East Coast, deficits are expected in many regions, moderate overall but more intense in Maine, northern Virginia, and central Florida, and surpluses in the Everglades.

From October through December, normal water conditions will return to much of the nation. However, widespread severe surpluses will persist in North Dakota, moderating to the east and south, and surpluses will increase near Lake Sakakawea. Severe to exceptional deficits will persist in the Salmon River region of Idaho and the Bear River region in the southwest leading into Utah. Pockets of moderate deficit will linger in southwestern Montana and small, isolated pockets of moderate surplus in the Pacific Northwest, Rockies, and Southwest. Moderate deficits will persist in eastern Maine and west-central Florida, and surpluses in the Everglades.

The forecast for the final months – January through March 2023 – indicates surpluses in the Northern Plains, pockets in the Northwest and Nevada, the southern Sierra Nevadas, and on rivers in the Rockies and Plains. Some deficits will linger in the northern Rockies and emerge in North Carolina.

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

IMPACTS
Widespread dry conditions in Texas - over 99 percent of the state - have prompted both mandatory and voluntary water restrictions with a least one community being asked to reduce daily water use by 40 percent. Across the border from McAllen, a migrant camp in Reynosa, Mexico housing over 2,000 people has begun water rationing. The drought is forcing many Texas ranchers to liquidate stock.

The recent heatwave has increased wildfire threats in the state and triggered outdoor burn bans. On 29 July, the temperature hit 115F (46C) in Wichita Falls. While Texas and Oklahoma claimed the dubious honor of the highest temperatures, over 100 million people in 28 states were under heat advisories.

A wildfire in California’s Yosemite National Park threated the park’s largest grove of majestic giant Sequoia trees and forced hundreds of people to evacuate.

Drought has also affected the US Northeast. Outdoor water use restrictions have been instituted in many New Hampshire communities. By mid-July, half of Maine was in moderate drought, an increase of nearly 20 percent over the prior week. The situation threatens the state’s blueberry growers who fear a repeat of 2020 when some lost over three quarters of their crop.

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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