United States: Water deficits in the West & Rockies will shrink

19 February 2021

THE BIG PICTURE
The 12-month forecast ending October 2021 indicates widespread water deficits of varying intensity in the U.S. West, Southwest, Texas, and Rocky Mountain States with anomalies bleeding into the Plains region. Deficits are expected to be exceptional in pockets of Southern California, Nevada, Utah, Arizona, New Mexico, Colorado, and Texas. Moderate to severe deficits are forecast for northern North Dakota.

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Deficits are forecast in the Deep South from the Mississippi Delta through southern regions of Mississippi, Alabama, Georgia, and South Carolina. Anomalies will be intense in the Mississippi Delta, the Middle Alabama River region, and near Savannah, Georgia. Deficits will cover much of Florida, mild in the Panhandle but exceptional between Jacksonville and Orlando. Surpluses are forecast near the Keys.

In the Mid-Atlantic, surpluses are forecast from Chesapeake Bay through much of Virginia and into North Carolina. Surpluses will be primarily moderate overall but somewhat more intense between the James and Roanoke Rivers. In the U.S. Northeast, western Pennsylvania can expect deficits ranging from moderate to severe, and intense deficits are forecast near the St. Lawrence River in Upstate New York and surrounding Lake Champlain along the New York/Vermont border. In the Great Lakes Region, moderate deficits will follow the Kankakee River in northern Indiana.

Outside the contiguous U.S., surpluses are forecast for most of the Hawaiian Islands with moderate deficits in Maui. Alaska can expect deficits in a large block of the northeast; in the center of the state at the confluence of the Yukon and Tanana Rivers; in large pockets of the west; and near Anchorage. Surpluses are forecast near Iliamna Lake and near Juneau. In Puerto Rico, moderate deficits are expected in the west.

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

The forecast through April indicates that deficits in the U.S. will shrink, relieving many areas in the Plains, Rockies, and the West. Severe to exceptional deficits will persist in eastern New Mexico, and deficits in central Colorado and North Dakota, while downgrading, will be severe to extreme. Deficits of generally lesser intensity are forecast for parts of Utah, Arizona, and California. Deficits in Texas will shrink. Surpluses will shrink in the Northwest and Great Lakes and will nearly disappear in the Mid-Atlantic. Moderate surpluses are forecast in southern Missouri, southern Illinois, Kansas, Oklahoma, and Arkansas. Surpluses are also forecast in a path from central South Dakota into north-central Nebraska. Moderate deficits are forecast in western Iowa, northern Indiana, and pockets of Ohio.

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In the South, intense deficits will persist in the Mississippi Delta and will increase in Florida, with exceptional anomalies from Jacksonville to Orlando. Surpluses will skirt Florida’s southern coast. Deficits are forecast for southern Alabama and the coastal region near Savannah, Georgia. Some moderate deficits will emerge across the shared border of the Carolinas. In the U.S. Northeast, deficits will shrink and pockets of moderate surplus will emerge.

From May through July 2021, normal water conditions will return to many regions as surpluses nearly disappear. Deficits, however, will increase becoming widespread in the West, Southwest, Rockies, and Texas, and will include exceptional anomalies in Utah, central Colorado, and the southern portion of California’s Central Valley. Deficits in North Dakota will moderate, and moderate deficits will emerge in Michigan’s Upper Peninsula. In Florida, deficits will downgrade. Moderate deficits are forecast in parts of the Carolinas, Georgia, Mississippi, and the Delta Region.

The forecast for the final months – August through November 2021 – indicates that deficits will shrink and downgrade in the Southeast, Texas, Southwest, and West but persist in the Rockies and increase in Montana and North Dakota. Moderate deficits are forecast for the Arkansas and Platte Rivers. Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
In February, widespread snow and ice storms in many regions of the country kept road crews busy, brought flooding to some areas, and disrupted power supplies. Storms lashed the Plains from the Dakotas through Texas and roared through the Mid-Atlantic States and the Northeast, closing some COVID-19 testing and vaccination sites in the District of Columbia, Maryland, and Virginia. Early in the month, Montague, New Jersey recorded 33 inches of snow, two feet fell in Massachusetts, and New York City’s Central Park saw over 17 inches. Coastal flooding was reported in New Jersey.

Mid-month, frigid conditions in Texas caused power outages affecting 4 million people including 1.4 million in the metropolitan Houston area. Dallas, normally a balmy 60°F, plummeted to 4°F (-16°C). Water pipes froze or burst, boil water advisories were initiated for nearly seven million Texans, and many households resorted to snow as their water source for flushing toilets, washing, and even drinking. As tap water dwindled, one hospital in Austin relocated critical patients.

At least 31 deaths were reported nationwide due to traffic incidents, hypothermia, and carbon monoxide poisoning. Federal emergency declarations were issued for Texas, Oklahoma, and Louisiana.

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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