United States: Intense water deficits expected in NM, FL, NC, SC

17 December 2021

THE BIG PICTURE
The 12-month forecast ending August 2022 indicates widespread water deficits from the southern Rockies through New Mexico, western Oklahoma, and most of Texas. Deficits will be exceptional in the Llano Estacado (Staked Plains), the Panhandles, and pockets in the Rio Grande region near Amistad and Falcon Reservoirs.

Deficits of varying intensity are forecast in Arizona, Southern California, central and southern Nevada, and pockets of Utah. The Pacific Northwest can expect surpluses in western Washington and pockets elsewhere in the region. Deficits are forecast for Idaho, Montana’s western half, and pockets of Wyoming, and will be particularly intense in the Salmon River Mountains of Idaho. Surpluses are forecast in eastern and south-central Idaho and north-central Nevada.

The Northern Plains can also expect surpluses in the Red River drainage basin of the Dakotas. The Great Lakes Region will experience deficits in northern Minnesota and northern Wisconsin through the western half of Michigan’s Upper Peninsula. Moderate deficits will straddle Wisconsin’s southern border. Widespread surpluses are forecast in Michigan’s Lower Peninsula reaching as far north as the “thumb” area, and south into most of Indiana and states in the central Ohio River Watershed. Surpluses will be exceptional in southeastern Michigan and spanning its southern border.

Surpluses will also be widespread in New York and northeastern Pennsylvania, with pockets in smaller states to the coast, and will include extreme anomalies in the Finger Lakes region of New York. A few pockets of deficit are forecast in the Northeast, including intense deficits near Lake Champlain in Vermont and moderate to severe deficits west of Moosehead Lake in Maine. In the Mid-Atlantic region, moderate deficits are expected in the Delmarva Peninsula.

Further south, widespread deficits reaching exceptional intensity are forecast from south-central Virginia through the Carolinas, moderating near Savannah, Georgia and inland. In Peninsular Florida, deficits will be widespread and intense in many regions, including near Lake George in the north and Lake Okeechobee in the south.

Outside the contiguous U.S., Alaska can expect deficits in the northeast and near Anchorage and Valdez in the south. Areas of surplus include Noatak National Preserve, Nome, the area west of Bethel, and the eastern reaches of the Alaska Range. Severe to extreme surpluses are expected in Hawaii and primarily moderate deficits in Puerto Rico.

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

The forecast through February 2022 indicates deficits, including exceptional anomalies, on the East Coast from the Delmarva Peninsula through the Carolinas and in southeastern Georgia. Intense deficits will persist in Peninsular Florida and emerge in southern Alabama, while mild deficits emerge in the Panhandle. Widespread surpluses are forecast from southern Michigan into northern Kentucky, and in central Illinois. Likewise, surpluses will extend through much of Pennsylvania and New York to the Atlantic and will be extreme in New York. In the Upper Midwest, deficits are expected in Minnesota, Wisconsin, and Michigan’s Upper Peninsula, and extreme surpluses in the Dakotas from Fargo past Sioux Falls. Deficits of varying intensity are forecast from Colorado into Kansas and Nebraska, and in New Mexico, Texas, and Oklahoma. Deficits are also expected in Arkansas and Louisiana. In the U.S. Northwest, surpluses will linger around Puget South, exceptional deficits in the Salmon River Mountains of Idaho, and moderate to severe deficits in western Montana. Mixed conditions are expected elsewhere in the Northern Rockies.

From March through May 2022, deficits will shrink and downgrade in the East with moderate to severe anomalies from South Carolina into its neighbors. Deficits will be widespread in Florida, but exceptional deficits will downgrade slightly. Moderate surpluses will persist in much of the Ohio River Valley and southern Michigan, increasing in Kentucky. Surpluses in the Northeast will shrink, with moderate pockets persisting in New York. Moderate to severe surpluses will continue to span the border of South Dakota and Minnesota and will emerge in eastern North Dakota. Deficits will nearly disappear in the Rockies but will remain widespread throughout New Mexico and into West Texas and the Panhandles and will include exceptional deficits. Deficits will emerge in Arizona and Death Valley, California. Moderate surpluses are forecast in coastal Oregon and pockets of Washington and Idaho. A pocket of intense deficit will continue in the Salmon River Mountains.

The forecast for the final months – June through August 2022 – indicates deficits in the Carolinas, California, Nevada, Colorado, Utah, and along rivers in the Southern Plains. Surpluses are forecast in the eastern region of the Dakotas, pockets of the Pacific Northwest, and southern Ohio River Watershed.

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

IMPACTS
Dozens of tornadoes cut a stunning path of destruction through six states in the South and Midwest on 11 December including a single event, dubbed the Quad State Tornado, that left a 200-mile scar in Kentucky alone. The death toll, currently at 88, is expected to rise. The storm dealt a powerful blow to the state that had just recently committed $1.1 million to recover from historic flooding in March.

Hawaii’s governor declared a state of emergency in early December when heavy precipitation produced flooding and snowfall. Over a foot of rain fell in Honolulu on Oahu in just 48 hours, flooding roadways and closing schools. Rainfall in Maui measured seven inches and eight inches of snow was reported at Mauna Kea on the Big Island. Power outages affected 42,000 people in Maui and Hawai’i.

Mid-December storms triggered flooding in Southern California and mudslides in burn scars left from last year’s Bond Fire. Mandatory evacuation was ordered for some neighborhoods in Orange County. In Northern California, 17 inches of snow forced closure of the Kirkwood Mountain Resort near Lake Tahoe and snowfall farther north closed Interstate 5 north of Redding.

High winds and dry conditions have contributed to wildfires in the Panhandles of Texas and Oklahoma.

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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