United States: Deficits persist in FL, GA, AK; surpluses ID

25 May 2017

The Big Picture

The 12-month forecast through January 2018 (above) indicates a pattern of water deficits and surpluses similar to the prior 12-month forecast with some exceptions. Changes include a retreat of deficits in the New England, and the appearance of relatively normal water conditions in the Ohio River Valley, as indicated in white, where moderate deficits had prevailed. Also, the forecast for southern seaboard states and the Deep South indicates diminished severity of deficits, as well as for states in the Lower Mississippi Valley. However, severe to extreme water deficits are forecast to persist in Florida, and may emerge in Delaware.

Exceptional surpluses are forecast for most of Idaho and parts of northern and western Nevada. Moderate to extreme surpluses are forecast for much of California from Bakersfield north, along with both deficits and surpluses in northern California. Surpluses of varying severity are expected in eastern Oregon and eastern Washington with both deficits and surpluses in the west. Surpluses of varying severity are also forecast for western Montana, western Wyoming, northwestern Utah, and southern Colorado. Moderate surpluses are forecast along the Missouri and Yellowstone Rivers, parts of the Rio Grande through New Mexico, and along the Arkansas River. Moderate to extreme surpluses are forecast for much of Wisconsin, southwestern Minnesota, northern Iowa, Michigan’s Lower Peninsula, and western Pennsylvania.

Outside the contiguous US extreme surpluses are forecast for the western portion of the island of Hawai’i. Moderate to occasionally extreme deficits are forecast for much of Alaska.

Impacts
A federal disaster declaration was approved for Washington, Utah, and Idaho after first-quarter flooding, mudslides, landslides and storms ripped through, and the threat of flooding continued well into April in some areas. Damages are estimated at about $30 million in the Magic Valley and Mini-Cassia areas of Idaho. 

April flooding was also reported in Missouri, Arkansas, and Illinois, breaking some 100-year records for river levels and claiming 10 lives throughout the Midwest and South. The Governor of Missouri declared a state of emergency and the National Guard was called in to assist in Arkansas. Many businesses along US 67 in East Pocahontas, Arkansas were under water; flood water from the Meramec River flowed over a railroad bridge in Valley Park, Missouri; and boats were used to carry sandbags down South Central Avenue in Eureka, Missouri. Missouri is facing $86 million in flood damage costs.

Many parts of the country experienced intense rainfall, including New York City, where flooding closed parts of the West Side Highway, the Van Wyck Expressway, two tracks and an entrance at Penn Station, and canceled hundreds of flights in and out of JFK, La Guardia, and Newark airports. 

Survey results from over 200 New York farmers indicate that losses from last summer's drought totaled 70 percent of unirrigated, rain-fed field crops and between 30 and 90 percent of pasture acreage.

Wildfire has burned through 130,000 acres (52,600 hectares) of Georgia's Okefenokee National Wildlife Refuge. Over 500 firefighters are fighting the blaze and dozens of nearby residents have been evacuated. Officials say it may take months to contain. 

In early May the water level in Georgia's Lake Lanier, which supplies water to 12 surrounding counties, was 8 feet below full and officials are asking Atlanta residents to conserve water as drought persists after the warmest April on record for the city. Farmers in South Georgia are becoming increasingly concerned about the drought and the costly consequences of irrigation.

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

The May through July forecast shows a significant reduction in the extent and severity of deficits in the Ohio River Valley, Lower Mississippi Valley, the Deep South, and South Atlantic states. However, primarily moderate deficits are expected to persist in Alabama, Georgia, and Florida. Parts of New England will transition from deficit to moderate surplus. Moderate to exceptional surpluses are forecast to emerge in the northern half of Michigan’s Lower Peninsula, and generally moderate surpluses will persist in much of Wisconsin, and in parts of Iowa, southern Missouri, southern Kansas, northeastern Oklahoma, and southern Colorado. Extreme to exceptional surpluses are forecast in Idaho and surrounding states. Surpluses in California’s northern two-thirds are expected to be moderate to occasionally exceptional. Both deficits and surpluses are expected in western Oregon and Washington.

The forecast for August through October indicates a pattern of water deficits and surpluses similar to the prior three months but with generally reduced severity. However severe to exceptional surpluses continue to be forecast for Idaho and into neighboring states during this period.

The forecast for the final three months – November through January – indicates persistent surpluses in Idaho.

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

Comment

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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