United States: Water surpluses in Gulf & N Atlantic

17 September 2021

THE BIG PICTURE
The 12-month forecast ending May 2022 indicates widespread water deficits in the U.S. West, Pacific Northwest, parts of the Rockies, and Northern Plains. Deficits will be exceptional in many areas including Oregon and Northern California, and extreme to exceptional in eastern North Dakota and northwestern Nebraska. On the Colorado River, deficits will be generally mild in the upper reaches and moderate to severe in the lower reaches.

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In Minnesota’s northern half, anomalies will be severe overall, generally downgrading in the south and through northern Iowa. Deficits are also forecast for Wisconsin’s northern and southern extremes, but surpluses will be dominant in a wide belt across the middle and will reach across Lake Michigan well into northern regions of Michigan’s Lower Peninsula as well as a pocket in the state’s southeast. Most of Illinois can expect moderate surpluses and pockets are forecast nearby in northern Missouri and in Indiana.

In the U.S. Northeast, deficits will skirt the northern reaches of New York, Vermont, and New Hampshire leading to more widespread anomalies in western Maine. However, surpluses will dominate the remainder of New York and reach through southern New England. Some moderate deficits are forecast spanning the shared border of the Carolinas. In Peninsular Florida, deficits will be widespread and will include extreme to exceptional deficits near Lake George in the north and Lake Okeechobee in the south.

In the Gulf States, surpluses will be widespread in Mississippi reaching into neighboring Alabama and southern Louisiana. Anomalies will be exceptional in coastal Mississippi and north of Lake Pontchartrain, Louisiana. Texas can expect surpluses along the coast from the Brazos River to Corpus Christi and following the Canadian River in the Panhandle. Surpluses will follow the Upper Canadian River region in New Mexico and reach into a pocket of south-central Colorado. Surpluses are also forecast in Colorado’s northeastern corner and in a pocket of north-central Kansas.

Outside the contiguous U.S., Alaska can expect intense deficits in the northeast and near Anchorage and Valdez in the south, and moderate deficits on the North Fork of the Kuskokwim River and near Norton Sound. Areas of surplus include Juneau, north of Iliamna Lake, west of Bethel, Noatak National Preserve, and the central Arctic Coast.

Most of the Hawaiian Islands will experience surpluses but moderate deficits are expected in Maui. Moderate to severe deficits are forecast for Puerto Rico.

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

The forecast through November indicates that deficits will shrink and downgrade considerably. In California, deficits will be mild overall but exceptional in Death Valley and severe in the Klamath River. Much of eastern Washington State will return to near-normal conditions but deficits are expected elsewhere, including exceptional anomalies in Oregon east of the Willamette Valley. Deficits are forecast throughout the Rockies, exceptional in Idaho’s Salmon River Mountains and a few other regions, and severe in northwestern Colorado. Deficits will follow the Missouri River through Montana.

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Much of the Great Plains region will see normal water conditions. Deficits will persist but downgrade in Minnesota and pockets in nearby states. Surpluses will increase in central Wisconsin, emerge in Lower Michigan, and become widespread from New York State to the Atlantic and through eastern Virginia. Though shrinking, intense deficits will persist in western Maine and pockets of northern Vermont. Some moderate deficits are expected in the Carolinas and intense deficits in Peninsular Florida. In the Gulf Region, surpluses will persist in Mississippi, southern Louisiana, and Alabama, and north through Tennessee and pockets in the Ohio River Watershed. In Texas, surpluses will persist from Corpus Christi to the Brazos River and on the Canadian River in the Panhandle. Surpluses elsewhere include a belt east of Phoenix, Arizona and the intersection of Colorado, Nebraska, and Kansas.

From December 2021 through February 2022, deficits will retreat from much of the western U.S. and the Northeast, persisting in Idaho and pockets of the Rockies, northeastern Minnesota, Florida, and southeastern North Carolina. Deficits will be intense in Idaho and southern Florida. Some pockets of surplus will emerge in the U.S. Northwest. Surpluses will nearly disappear in the South but widespread, moderate to severe anomalies are expected from the Great Lakes States into much of the Northeast.

The forecast for the final months – March through May 2022 – indicates a transition to moderate surplus in the Rockies. Deficits are forecast for Peninsular Florida and northeastern Minnesota. Please note that WSIM forecast skill declines with longer lead times.

IMPACTS
Hurricane Ida raged through the Gulf Coast and swept a path reaching into New England at the end of August leaving flooding and destruction. Over a million customers lost power in Louisiana and 60,000 in Mississippi. The storm surge was strong enough to create a negative flow on the Mississippi River, temporarily reversing the river’s flow.

An oil slick off the Louisiana coast was likely the result of Ida’s effect on submerged pipelines in the region and the storm disrupted over 90 per cent of the crude oil and gas production along the highly petro-industrialized Gulf Coast.

Of the 14 deaths in New Orleans, most were attributed to heat after Ida knocked out power. Seven nursing home patients died in Louisiana after hundreds from seven homes in the region were evacuated to a warehouse where electricity and sanitation were compromised. An alligator attack claimed one life in Louisiana.

But as the storm worked its way into the Mid-Atlantic, over 50 deaths there were caused by flooding and spin-off tornados, including nearly a dozen who died in flooded basement apartments in New York.

Initial estimates of damage costs from Ida are around $95 billion.

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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