United States: Exceptional deficits to emerge in SW states

25 October 2024

THE BIG PICTURE

The forecast ending in June 2025 indicates that exceptional deficits will occur in southwestern states, as well as in some areas of the Midwest. Severe to exceptional surpluses will linger in southern regions of Florida and in much of the noncontiguous U.S.

Severe to exceptional deficits are anticipated in:

Eastern to southeastern California, throughout much of the Inland Empire and Sierra Nevada regions. These deficits continue into southernmost portions of Nevada and throughout western to southern New Mexico.
Central and southern Arizona, in areas near the city of Albuquerque, the Zuni Reservation, and along the southern border of the state. These deficits continue into pockets of western Texas, throughout El Paso and Hudspeth County.
Northeastern Wyoming, in central areas of Campbell and Crook County. Nearby, exceptional deficits will appear in most of western Nebraska and in regions along the border of northwestern South Dakota and southwestern North Dakota.
West Virginia, widespread throughout the state. Severe deficits continue north into southeastern Ohio.
Eastern coastal regions of Massachusetts and Maine.

Severe to exceptional surpluses are expected in:

Southern Florida, throughout regions south of Lake Okeechobee.
Much of western Alaska, with exceptional surpluses appearing in the North Slope Borough, the Seward Peninsula, the Kusilvak Census Area, and central areas of the Yukon-Koyukuk Census Area.
Eastern Puerto Rico, in regions east of the city of Caguas.

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

FORECAST BREAKDOWN
The forecast through December 2024 indicates that widespread severe to exceptional deficits are expected to appear in the Midwest, Southwest, and Northeast, with the most intense anomalies appearing throughout the Midwestern Plains, as well as some portions of the Great Lakes region. Severe to extreme surpluses will continue throughout Florida and southern Georgia, as well as across much of Alaska and eastern Puerto Rico.

From January through March 2025, widespread deficits in the Midwest are expected to downgrade, becoming mostly moderate to severe deficits. Some pockets of exceptional deficits are anticipated in southern New Mexico, western Wyoming, and in several areas of the Great Lakes region. Severe to extreme surpluses will endure in southern Florida and much of Alaska. Surpluses in eastern Puerto Rico will expand to central regions.

The forecast for the final months – April through June 2025, indicates that most deficits in the Midwest will dissipate. Severe surpluses are expected to linger in some regions of southern Florida, as well as northern and central Alaska.

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

IMPACTS
Hurricane Helene devastated several regions of the southeast in late September, including many areas of western North Carolina. According to the North Carolina State Climate Office, regions of Asheville, North Carolina received over a foot of rainfall before the storm. This saturated soils and filled rivers and streams, which compounded with orographic lifting to produce trillions of gallons of water into the area. According to Marshall Shepherd, director of the Atmospheric Sciences Program at the University of Georgia and former president of the American Meteorological Society, these conditions worsened the effects of the storm, allowing areas to experience catastrophic rainfall earlier and longer.

In southeastern Arizona, Fort Huachuca, an United States Army base, was recently criticized for depleting significant amounts of water as the entire state experiences intense drought. A study found that the base and nearby affiliated communities withdraw an estimated 10,000 acre feet per year of water. Additionally, a link to an approximate overdraft of 4,000 acre feet of water from the San Pedro River. Dave Roberts, a local water resource manager and strategy consultant in Arizona, stated that though the fort has made progress to offset its environmental impact, there is simply not enough groundwater to realize their goal. “I don’t think they’ll ever be successful,” said Roberts. “They’re continuing to pump groundwater, and they have no way of mitigating the pumping effects, and the only way you do it is to bring additional water into the region and not pumping.”

In mid-October, a storm brought rain, high winds, and street flooding to Whittier, Alaska. Roughly six inches of rain was recorded over October 11th and 12th, as well as a significant increase in high-tide levels, which reached 10.3 and 10.8 feet on the same days, respectively. On the 12th, city officials stated that “Last night, we experienced more rainfall than usual, which, combined with high tide, led to temporary water accumulations,” causing road closures in the area. Officials estimated that the standing water reached nearly 2.5 feet at its deepest.

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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