United States: Intense water deficits ahead in S. California

21 September 2022

THE BIG PICTURE
The 12-month forecast ending May 2023 indicates water deficits of varying intensity in the U.S. West, Rockies, Central Plains, Texas, and along the East Coast. Surpluses are forecast in the Dakotas and pockets of the Southwest.

In the West, deficits are expected throughout most of California and central and southeastern Oregon. Deficits are forecast in the Rockies and Nevada along with some isolated pockets of surplus. Areas with a forecast of exceptional deficit include California’s Coastal Ranges, the Salmon River Mountains in Idaho, and the Utah Rockies.

The Southwest can expect pockets of surplus in New Mexico near the San Juan and Upper Canadian Rivers and in the Gila National Forest, and in eastern Arizona.

Deficits will be widespread in Nebraska, western Kansas, and much of Iowa. Anomalies will be exceptional in western Nebraska reaching into Wyoming, Colorado, and Kansas. In Texas, generally moderate deficits are forecast in the Brazos River Watershed and reaching to San Antonio. Severe deficits are forecast in a pocket around Houston and mixed conditions in the Panhandle.

In the Northern Plains, moderate to severe surpluses will be widespread from North Dakota’s eastern half into nearby areas of South Dakota and Minnesota. Surpluses are also expected near western Lake Sakakawea in North Dakota.

The U.S. Northeast will see deficits, particularly Massachusetts, Connecticut, and Rhode Island, with pockets near Augusta, Maine and Burlington, Vermont. Anomalies will be extreme near Boston. Severe deficits are forecast in the Middle and Lower Hudson River Valley, and moderate deficits through New Jersey. Pockets are expected in Virginia including the Eastern Shore. Deficits will be severe in eastern North Carolina, generally moderate in South Carolina and southeastern Georgia, and intense in Peninsular Florida, especially from Orlando past Lake Okeechobee.

Outside the contiguous U.S., moderate deficits are forecast in western Puerto Rico and surpluses in several of the Hawaiian Islands. Alaska can expect widespread deficits in its northeast quadrant, and surpluses from the Alaska Peninsula to the Kuskokwim River and near Juneau, Nome, and west of Bethel.

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

The forecast through November indicates intense deficits in Southern California, and mild to moderate deficits in the north and Oregon. Deficits will continue in the Northern Rockies - exceptional in the Salmon River Mountains of Idaho – and in pockets of the Southern Rockies. Surpluses are forecast in the Southwest including along the Gila, San Juan, and Upper Canadian Rivers. In South Dakota, surpluses and transitional conditions are forecast in the east reaching into South Dakota and Minnesota, and near Lake Sakakawea. Deficits will shrink and moderate in the Central Plains and Iowa and nearly retreat from Texas. Moderate surpluses will emerge along the Rio Grande, increase in southern Mississippi, and persist in eastern Kentucky and West Virginia. Deficits will remain widespread on the East Coast from Massachusetts through North Carolina and in Florida.

From December 2022 through February 2023, normal water conditions will return to much of the nation. However, deficits in Florida will increase and intensify; moderate to extreme deficits will persist in North Carolina, crossing into Virginia and South Carolina; and a pocket of severe deficit is forecast in southeastern Georgia. In the Northern Rockies, deficits will continue from Idaho into Montana and southwestern Wyoming into Utah. Small pockets of surplus are expected in the Pacific Northwest and Rockies, including near Salt Lake City, and pockets will persist in the Southwest. Severe surpluses are expected in South Dakota’s eastern half and nearby border regions, re-emerging in the Upper James River region, and are also forecast near Lake Sakakawea. Moderate surpluses will emerge in pockets throughout the Great Lakes Region, trailing into the U.S. Northeast.

The forecast for the final months – March through May 2023 – indicates moderate deficits in Peninsular Florida and surpluses in the Rockies, pockets of New Mexico, Lake Sakakawea, and near Red Lake, Minnesota.

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

IMPACTS
Hurricane Fiona roared over Puerto Rico in late September, plunging the island into darkness as it knocked out power and water service to most of the region’s 3.1 million residents. At least two deaths were reported and 1,000 people were rescued. Some areas were submerged in up to 30 inches of rain in flooding that triggered mudslides. Residents of the Playita community in Salinas used a kayak to navigate flooded streets. Several airports closed or temporarily halted flights. A federal emergency declaration was issued enabling the Federal Emergency Management Agency to begin relief efforts.

Thousands of miles away, some Alaskans were fighting their own battles with storm damage as Typhoon Merbok caused widespread flooding in coastal areas of the state’s west. Water surged through the streets of a number of communities along a 1,000-miles stretch of the coast including Nome, damaging homes, buildings, roads, and airports and creating power outages. Hundreds of people were evacuated. Though a state disaster declaration was declared, federal help is problematic in the remote communities of the state reachable only by air or water. Some tribal communities have lost fuel stockpiled for winter heat and travel, and hunting, a subsistence activity rather than sport, has been curtailed. The village of Newtok - relocated just a few years ago due to climate change - was inundated and cut off from the airport.

In the U.S. West, the Mosquito Fire near Lake Tahoe in California has become the state’s largest fire this year, consuming 76,000 acres. A heat wave and dry conditions combined to create a tinderbox effect, turning the threat of fire into a reality. The blaze has commanded the attention of over 3,000 fire personnel, 80 water tenders, and 65 bulldozers. Smoke from the fire has compromised air quality in the Sacramento area.

As temperatures in the state soared at the end of August and into September straining the power grid, officials declared a grid emergency. Residential and business consumers were asked to conserve energy to avoid blackouts, a condition narrowly averted.

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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