United States: Widespread, intense water surpluses ahead from WI to TX

26 November 2018

THE BIG PICTURE
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 the NOAA National Hurricane Center.

The 12-month forecast ending July 2019 indicates water surpluses of varying intensity in three regions: the East Coast from southern New Hampshire through North Carolina; much of Texas into Oklahoma and Kansas; and Iowa, southern Minnesota, southern Wisconsin, and Michigan’s western Upper Peninsula. Surpluses are expected to be extreme to exceptional in the heart of Texas surrounding the Edwards Plateau, pockets of Iowa and Wisconsin, and eastern Pennsylvania.

Deficits will dapple the Upper Midwest and West and will be primarily moderate, though more intense conditions are forecast for central Colorado and the Pacific Northwest. Deficits are also forecast on the opposite end of the country in northern New York, Vermont, and Maine, and will be severe to exceptional in New York and Vermont. Fairly intense deficits are forecast for southern Florida, particularly south of Lake Okeechobee, and primarily moderate deficits are expected in Louisiana, Mississippi, Alabama, and central Georgia. Conditions in the Ohio River Valley will be relatively normal with some mild deficits. Pockets of moderate deficit are expected in Michigan.

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 in the Seward Peninsula, around Anchorage, and the Alexander Archipelago in the Alaska Panhandle.

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

The forecast map through January calls attention to significant surpluses. A swath of surpluses will cut a wide north/south path from Michigan’s Upper Peninsula through Wisconsin, Iowa, eastern Kansas, eastern Oklahoma and central and eastern Texas, as well as pockets in nearby states to the east. The pattern will include surpluses of exceptional intensity in southern Wisconsin, southern Minnesota, eastern Iowa, a line down the center of Kansas and Oklahoma, and vast block in the heart of Texas. Moderate to extreme surpluses are forecast for Michigan and the Ohio River Valley leading into widespread surpluses in the east from Maine to South Carolina. Surpluses will be extreme in Pennsylvania. Surpluses are also expected in northern Nebraska, the Upper Cheyenne River crossing the border of South Dakota and Wyoming, southeastern and western Montana, and northeastern Washington.

Some deficits are expected in the Southeast with moderate deficits in Mississippi, Alabama, southeastern Georgia, and moderate to extreme deficits in Florida. Mild deficits are forecast for much of the western half of the country, except previously noted surpluses, but deficits may be more intense in central Colorado, the Rio Grande through New Mexico, northern Utah, northwestern Wyoming, and northwestern California into Oregon.

From February through April, surpluses will shrink considerably, leaving relatively normal conditions east of the Mississippi with some primarily mild deficits in the Ohio River Valley. Surpluses in Texas will diminish but persist. Other areas of surplus include: southern Minnesota into Iowa; the Missouri River; the Arkansas River in Kansas and Colorado; central Oklahoma; Idaho, western Montana, and northern Washington. Surpluses are expected to emerge in California and Nevada around Lake Tahoe.

The forecast for the final months – May through July – indicates widespread moderate to severe deficits from the Great Lakes States through the Northeast, Ohio River Valley, and into the Deep South. Relatively mild deficits are expected west of the Mississippi, nearly normal conditions in California, and surpluses in Texas.

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

IMPACTS
A notorious wildfire that began on November 8 ravaged northern California’s Butte County before finally being contained November 25. California’s most deadly fire, the Camp Fire, killed at least 85 people and has left hundreds still missing as of the end of November. Almost 14,000 homes, 514 businesses, and 4,265 other buildings were destroyed.

The Woolsey Fire in Ventura County and the Hill Fire in the Santa Rosa Valley burned thousands of acres. Even before this month’s barrage of new wildfires, the Ranch Fire (Mendocino Complex Fire) set California’s record for the largest wildfire. Drought conditions in the state have provided ready fuel for the fires.

The National Integrated Drought Information System, a branch of National Oceanic and Atmospheric Administration, estimates that 3.8 million people, 99 percent of Oregon’s population, are experiencing drought conditions this year. The state’s firefighting costs set a record $514 million this year, and only four percent of Oregon rangelands are considered in good condition, grappling with low soil moisture. The general manager of the North Unit Irrigation District in the Deschutes Basin, east of the Cascades, estimates that 25 percent of the district’s farmland won’t be planted next spring due to anticipated water shortage. Outdoor watering was banned in some areas, exacerbating tensions over government regulatory interference in the Oregon interior. And in the face of an El Niño forecast this winter, which often means drier-than-normal conditions, Oregonians are bracing for prolonged drought.

Exceptional flooding in Texas elevated silt levels in the municipal water systems of Austin, limiting the treatment capacity and causing the city to issue a boil water notice for all customers, as well as asking customers to conserve water. In a kind of irony, elevated silt due to catastrophic flooding depressed the treated water levels of the municipal reservoirs to about a third of normal processing capacity. The advisory is unprecedented in the utility’s history.

Prolonged rains lasting weeks led Texas Governor Greg Abbot to declare a state of disaster in 18 counties in Central and South Texas, lifting state restrictions and regulations in response to the flood emergency.

The season’s first nor’easter downed power for 35,000 in the mid-Atlantic and New England late last month. Strong winds felled trees and drove coastal flooding from New Jersey to Long Island Sound, shutting down northbound lanes on FDR Drive in Manhattan.

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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