United States: Water surpluses forecast for NE, IA, CO, ID, NV, CA

18 April 2019

THE BIG PICTURE
The 12-month forecast ending December 2019 indicates that water surpluses of varying intensity will affect many parts of the conterminous U.S.

In the center of the country, primarily moderate to severe surpluses are forecast in eastern South Dakota, southern Minnesota, Iowa, western Illinois, Nebraska, Kansas, and Missouri, but anomalies may be more intense near Sioux Falls (SD) and in south-central Nebraska. Surpluses are expected to be severe along the Mississippi River from Iowa to the Gulf of Mexico. Surpluses of generally lesser intensity are forecast for pockets of Oklahoma, Arkansas, and Texas including parts of the Pecos River and the Rio Grande. Surpluses will, however, be extreme to exceptional around Abilene, TX. In the northern Midwest, some severe deficits are forecast for the western half of Michigan’s Upper Peninsula, and some moderate deficits in pockets of northern Minnesota and North Dakota.

Surpluses are forecast in the central Ohio River Basin and are expected to be especially intense around Knoxville, TN. In the East, a patchwork of anomalies is forecast from Maine through Florida, though most conditions are forecast to be relatively mild. Moderate deficits are expected in pockets along the coast in Delaware and Virginia, and deficits in North and South Carolina could be severe. Some pockets of moderate deficit are also expected in Florida.

In the western half of the U.S., surpluses are forecast throughout California, down the center of Oregon, and in Idaho, southwestern Montana, Nevada, Utah, Colorado, south-central Wyoming, and Arizona. Surpluses will be intense in pockets of Nevada, eastern Idaho, Montana, and Colorado. Primarily moderate deficits are expected in western Oregon, Washington, and pockets of northern Wyoming.

Outside the contiguous U.S., in Hawaii surpluses are forecast for western Hawai’i, Moloka’i, and Lana’i, and moderate deficits on Maui. In Alaska, surpluses are forecast at the base of the Alaska Peninsula on Bristol Bay and reaching inland. Surpluses are also forecast southeast of Barrow in the far north and along the Upper Koyukuk and central Yukon Rivers and will include exceptional anomalies. Deficits are expected in the Seward Peninsula and into western Alaska, along the Tanana River through Fairbanks, around Anchorage, and in the Alaska Panhandle. Deficits may be extreme around Fairbanks and Anchorage. Severe deficits are forecast for western Puerto Rico and moderate deficits in the east.

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

Most notable in the April through June forecast is the absence of widespread, intense surpluses observed East of the Mississippi in prior months and a transition to surplus in the Rockies.

In the Northeast, a few areas of scattered, surplus are forecast. Moderate to severe deficits are expected in western Pennsylvania, West Virginia, eastern North Carolina and southern South Carolina, and Georgia; and, curving around the Gulf through the Florida Panhandle, and southern Alabama and Mississippi.

In the center of the country, surpluses ranging from moderate to extreme are forecast for eastern South Dakota, southern Minnesota into Wisconsin, Iowa, Nebraska, Kansas, the Arkansas River, northern Missouri, pockets of Oklahoma, and a large pocket in Texas surrounding Abilene where surpluses could reach exceptional intensity. Moderate deficits are forecast for eastern Arkansas and pockets of Louisiana, though moderate surpluses are expected on the Lower Mississippi through Louisiana.

Widespread surpluses of varying intensity will emerge in the Rocky Mountain States including Idaho, Montana, Wyoming, Nevada, Utah, and Colorado, and will be exceptional in many pockets. Primarily moderate surpluses are forecast on the Missouri and Yellowstone Rivers. Moderate to severe surpluses are forecast for nearly all of California, and in northern Arizona and Oregon.

From July through September, surpluses will shrink and downgrade. Moderate to severe surpluses are forecast for eastern South Dakota, southern Minnesota, Iowa, Nebraska, and into pockets of Arkansas and Kansas. Surpluses are also expected on the Canadian River in Oklahoma and on the Pecos River in Texas. Pockets of surplus are forecast for the Rocky Mountain States and moderate surpluses in central Arizona, pockets of southern and central California, most of northern California, and pockets in Oregon. Some deficits are forecast in Washington, northern Wyoming, and northern Minnesota. In the East, moderate surpluses are forecast for northern New York, Vermont, and western New Hampshire. Primarily moderate deficits are expected from southern Pennsylvania through the Virginias and Carolinas, in Georgia, northern Florida, and southern Alabama and Mississippi.

The forecast for the final months – October through December – indicates surpluses in South Dakota, Nebraska, Iowa, the Lower Mississippi Basin, eastern Texas, the Deep South, pockets throughout the Rockies, and the Yellowstone River. Some moderate deficits are forecast for northern California, western Oregon and Washington, the Mid-Atlantic States, and Florida.

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

IMPACTS
A late winter storm pummeled the Midwest in mid-March, dropping snow and rain in what amounted to the worst flooding in 50 years across large swathes of the grain belt. As the Platte and Missouri Rivers reached record high levels, over 10 million people from Nebraska to Wisconsin were placed under flood warnings. In Iowa an ice jam and flooding on the Turkey River washed away a railroad bridge, requiring rail shipments to be rerouted. Floods shut down grain processing plants and ravaged silos in eastern Nebraska, crippling 13 percent of the country’s ethanol production and destroying grain caches which are often covered neither by crop insurance nor by federal disaster aid. The millions of dollars in loss is partially due to the unprecedented level of U.S. grain stores at the time of the flood amid a current trade war with China. In Nebraska alone, agricultural damage is estimated at $1 billion.

The flooding caused a humanitarian disaster on the Pine Ridge Indian Reservation in South Dakota, where a lack of training, manpower, and equipment has left the Oglala Sioux Tribe largely stranded in a state of emergency. Help from outside the tribe was slow to arrive in the recent flooding disaster, and people are frustrated with the tribal government’s response which was limited by a lack of adequate resources to respond to food shortages and drinking water losses.

The Willamette River crested, flooding Corvallis, OR this month and closing the Corvallis-Lebanon Highway 34.

Southeast Alaska, which is currently under dry-to-drought conditions, reached a temperature of 70 degrees Fahrenheit (21 degrees Celsius) last month at the earliest time on record for the state.

As about a third of the United States gross national product is generated from industries that are directly vulnerable to extreme weather, and the United States loses more money to extreme weather events over time, new business in forecasting extreme weather events and mitigating risk has emerged in direct service to the shipping, petroleum, and utilities industries.

The U.S. Air Force has announced that it needs nearly $5 billion in additional funding to rebuild two bases damaged by Hurricane Michael and last month’s flooding.

Hurricane names Florence and Michael are now retired, as is standard practice when storms are so destructive that reusing the names would be insensitive. Since storms were first named in 1953, 88 names have been retired.

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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