United States: Intense water surpluses ahead for Iowa & Wisconsin

18 October 2018

THE BIG PICTURE
The 12-month forecast ending June 2019 indicates significant water deficits in the Pacific Northwest, particularly western Oregon where deficits will be exceptional. Extreme to exceptional deficits are forecast for northern Utah and western Colorado, with deficits of generally lesser intensity in Northern California and in pockets throughout the Rocky Mountains. Elsewhere in the West, surpluses are forecast for southern Montana, some pockets of southern California, and north-central Arizona. Conditions of both deficit and surplus are forecast for parts of the Northern Rockies.

In the center of the nation, surpluses are expected to be widespread and intense in Iowa, reaching into southern Minnesota, southern Wisconsin, and northern Nebraska. Moderate surpluses are expected along the Missouri River, and a pocket of more intense surpluses is forecast for the Black Hills along the South Dakota/Wyoming border. Moderate to extreme surpluses are forecast for southern Texas and moderate surpluses in southern Oklahoma. Missouri will see some primarily moderate deficit conditions as will the Upper Midwest along the borders of Minnesota and the Dakotas, but deficits may be severe in Minnesota. Scattered mild to moderate deficits are expected in Michigan and its southern neighbors.

In the East, intense surpluses are forecast for eastern Pennsylvania and into nearby states, and in southeastern North Carolina. Parts of the Northeast are expected to experience deficits, reaching exceptional intensity in northern New York and northern Vermont but primarily moderate in Maine. Some deficits are also expected in pockets of the Deep South, and in southern Florida.

Outside the contiguous US, surpluses are forecast for Hawaii and deficits in Puerto Rico. A complex patchwork of conditions is forecast for Alaska including: surpluses in the southwest from Bristol Bay well into the interior, and in the upper reaches of the Copper and Susitna Rivers; and deficits around Anchorage, the Kenai Peninsula, and the Alexander Archipelago in the Alaska Panhandle.

NOTE: The WSIM model makes use of seasonal temperature and precipitation forecasts produced by the U.S. National Oceanic and Atmospheric Administration (NOAA) Climate Forecast System Version 2 (CFSv2). These forecasts predict broad temperature and precipitation patterns, but do not effectively predict singular events such as tropical storms. Detailed outlooks and analyses of tropical storms are available from NOAA National Hurricane Center.

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

The forecast map through December calls attention to significant surpluses. Surpluses are forecast for Iowa, southern and eastern Minnesota, Wisconsin, and Michigan’s western Upper Peninsula and west-central Lower Peninsula. Surpluses will be exceptional throughout much of Iowa. Surpluses are also forecast for northern Nebraska, the Black Hills along the Wyoming/South Dakota border, and Montana. Moderate to extreme surpluses are forecast for the Ohio River Basin. Nearby in eastern Pennsylvania surpluses could be exceptional, surrounded by conditions of generally lesser intensity reaching north through southern New Hampshire and south through northeastern South Carolina. Surpluses of varying intensity are also forecast for southern Texas, southern Oklahoma, and Missouri.

Deficits are expected in the US Southeast, primarily moderate but more intense in Florida surrounding Lake Okeechobee. Moderate deficits are forecast for Missouri. Severe to exceptional deficits are expected along the Arkansas River through Kansas and Colorado, in western Colorado, and northeastern Utah. Deficits are forecast along the Canadian River through Oklahoma and the Texas Panhandle, and along the Rio Grande through New Mexico. In the Pacific Northwest, moderate deficits may linger in Oregon. On the opposite side of the country, some severe deficits are expected in Maine, northern Vermont, and northern New York.

From January through March, conditions in the Ohio River Valley will normalize but widespread surpluses will continue in aforementioned areas of Iowa, Minnesota, Wisconsin, and Michigan, though the extent of exceptional conditions will diminish. Surpluses will increase in Montana, and pockets of surplus, primarily moderate, will emerge in the Rockies, Pacific Northwest, along the Missouri River, California’s southern half, and Arizona. Fairly intense deficits will persist in central Colorado and northwestern Wyoming, and moderate deficits along the Canadian River through the Texas Panhandle. In southern Texas, surpluses will downgrade somewhat. In the East, moderate surpluses remain in the forecast for Pennsylvania and neighboring states. Conditions in the Deep South and Southeast will transition from deficit to near-normal in most areas, but southeastern Georgia and much of Florida will transition to moderate surplus, while deficits around Lake Okeechobee diminish.

The forecast for the final months – April through June – indicates widespread deficits from the Great Lakes States through the Northeast, Ohio River Valley, and into the Deep South. Deficits are also forecast for the Pacific Northwest. Areas of surplus include: Florida, Oklahoma, the Arkansas River, Colorado, parts of the Northern Rockies, pockets in the Southwest, and along parts of the Rio Grande.

(It should be noted that forecast skill declines with longer lead times.)

IMPACTS
Hurricane Michael ravaged the southeastern United States this month making landfall in Bay County Florida as the first Category 4 hurricane on record to make landfall in the Florida Panhandle. At least 32 people were killed across Florida, Georgia, North Carolina, and Virginia. As of mid-October, authorities were still finding bodies amid massive swathes of debris in coastal Florida. Over 2,500 structures were damaged and hundreds destroyed. A Boston-based catastrophe modeling firm estimated insured losses associated with Michael to be nearly $8 billion, including wind and storm surge damage to homes, cars, and commercial properties. That figure did not include losses backed by the National Flood Insurance Program.

An image of a single standing, unscathed home on Mexico Beach, Florida is circulating speculation on future building codes for new buildings constructed on the coast. Built with reinforced concrete walls, 40-foot driven pilings, and steel roof cables, the building exceeds Florida’s current building codes and cost 15 to 20 percent more than code-compliance.

Flooding of the Llano River in Texas killed at least two people, collapsed a bridge, and flooded homes this month as the river rose 35 feet in 24 hours, Farther north in the Dallas/Fort Worth area, recent heavy rainfall has made this autumn the wettest on record with over 23 inches.

Some farmers and municipalities in northern Vermont have had to haul in water as drought has depleted supplies, especially in private wells.

The governor of Utah declared a state of emergency this month due to extreme drought, and asked Utah residents to use water wisely in the coming months. Low snow pack and an unusually hot summer left many reservoirs half empty.

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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