United States: Water surpluses will continue to dominate central states

16 August 2019

The 12-month forecast ending April 2020 indicates that water surpluses of varying intensity will affect a vast path down the middle of the nation through the Mississippi River Basin as well as westward well into the Missouri, Arkansas, and Red River Basins, and north through much of Michigan. Surpluses are expected to be extreme to exceptional in South Dakota, Nebraska, Kansas, Oklahoma, southeastern Minnesota, the northern region of Michigan’s Lower Peninsula, and along portions of the Missouri and Arkansas Rivers. Severe surpluses are forecast along the Mississippi River. Texas, too, can expected surpluses in the western Edwards Plateau and in the northeast.

Surpluses are also forecast scattered throughout the Rockies, in eastern Nevada and along the Colorado River. Primarily moderate surpluses are forecast for central California. On the opposite coast, moderate surpluses are forecast for the U.S. Northeast and in the Tampa Bay area of Florida.

Deficits are expected in the Pacific Northwest, southeastern New Mexico, north-central Minnesota, along the Atlantic coast from the Carolinas into Georgia, and a pocket in southern Florida.

Outside the contiguous U.S., surpluses are forecast for much of Hawaii. In Alaska, surpluses are forecast in the Koyukuk River watershed in the center of the state, and in the interior northeast of Bristol Bay. Moderate to exceptional deficits are forecast in the Tawana River region around Fairbanks, and along the Gulf of Alaska from Kodiak through Anchorage and past Valdez. Moderate to severe deficits are forecast for Puerto Rico.

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

Water surpluses are forecast to be the dominant anomaly in the U.S. through April 2020.

From August through October 2019, observed surpluses along the Mississippi River, its tributaries, and states on both banks of the river will shrink and moderate. However, significant surpluses are forecast in a column from South Dakota through Nebraska, Kansas, Oklahoma and into central and eastern Texas, and will include extreme to exceptional anomalies, that will be particularly widespread in South Dakota.

Surpluses of varying intensity are expected in parts of the Rockies including southern Idaho and southern Montana, Wyoming, western Colorado; as well as western Utah, eastern Nevada, central Arizona, and northeastern New Mexico. Primarily moderate surpluses are forecast throughout nearly all of California and into pockets of central Oregon. Moderate surpluses are forecast for the northern portion of Michigan’s Lower Peninsula, and pockets in the Ohio River Valley, trailing spottily northeast. Surpluses are also forecast for southwestern Florida spreading from Tampa Bay.

Areas of deficits include the Pacific Northwest, northern Minnesota, and the eastern regions of the Carolinas, dissipating as they reach into southern Georgia and Alabama and the Florida Panhandle. A pocket of extreme deficit is forecast in Florida’s southern tip.

From November 2019 through January 2020, intense surpluses will persist in a column from South Dakota through Oklahoma, moderating somewhat in eastern portions of the affected states. Surpluses will remain intense and widespread in South Dakota. Surpluses will also persist in parts of the Rockies, western Utah, Nevada, and pockets of Arizona and New Mexico. Surpluses will shrink in Texas, nearly disappear in California, and normalize in the Lower Mississippi region. Moderate surpluses will persist in the Upper Mississippi Basin, in Michigan, and the northern portion of the Ohio River Basin. Relatively normal conditions are expected elsewhere in the contiguous U.S. as deficits diminish, though a small pocket of severe deficit will persist in north-central Minnesota.

The forecast for the final months – February through April 2020 – indicates surpluses in the Plains States, Rockies, and California with intense, widespread surpluses in South Dakota, and a pocket of persistent deficit in north-central Minnesota.

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

[updated 26 Aug 2019]
July 2018 through June 2019 was the wettest twelve months in United States history, exceeding the average by 7.9 inches, according to the National Oceanic and Atmospheric Administration.

This month, flash flooding of two-to-three feet partially submerged cars in some parts of Baltimore following a severe thunderstorm. Heavy rain collapsed a wall of a New York subway station in Long Island City. Rushing waters swept one commuter off his feet as an oncoming train made its arrival, and turned stairwells into waterfalls.

Delayed monsoons have extended Arizona’s fire season past its typical end in mid-July. July was Phoenix’s sixth warmest, with an average high temperature exceeding 108 degrees Fahrenheit.

Oregon’s conifers are showing signs of suffering and succumbing to several years of drought.

U.S. Sugar has filed a lawsuit against the Army Corp of Engineers, alleging that the agency has been “releasing unprecedented amounts of water” from Florida’s Lake Okeechobee, maintaining the lake at a level lower than stipulated in the 2008 Lake Okeechobee Regulation Schedule.

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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Many analyses reported in ISciences-authored blog posts are based on data generated by the ISciences Water Security Indicator Model (WSIM). Other sources, if used, are referenced in footnotes accompanying individual posts. WSIM is a validated capability that produces monthly reports on current and forecast global freshwater surpluses and deficits with lead times of 1-9 months at 0.5°x0.5° resolution. This capability has been in continuous operation since April 2011 and has proven to provide reliable forecasts of emerging water security concerns in that time-frame. WSIM has the ability to assess the impacts of water anomalies on people, agriculture, and electricity generation. Detailed data, customized visualizations, and reports are available for purchase.

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