The Big Picture
Overall, for the 12-month period ending December 2016 (below) conditions in many parts of the US are forecast to be drier than normal. Moderate (5-10 year) to exceptional (greater than 40 years) water deficits are expected in the East through the Appalachians; the Midwest through the Ohio and Mississippi Valleys; across the Northern Plains and parts of the Central Plains; and in the Southwest. Surpluses are forecast in Idaho and northeastern Nevada; the shared border of Minnesota and Iowa; the Canadian and Rio Grande Rivers; and southern Florida. Both deficits and surpluses are expected in the Pacific Northwest.*

Impacts
Though this winter's El Niño-driven storms have helped boost water levels in California's reservoirs, they're just "a bandaid on a gaping wound" says one USC paleoclimatologist. On March 30th water content of the snowpack was 87% of normal, much better than last year's 5% but not enough to pull the state out of drought. This could be a glimpse of the new normal - California's Department of Water Resources predicts that a quarter of the Sierra Nevada Mountains' snow cover will disappear by 2050.

Though still early in the growing season, the USDA National Agricultural Statistics Service reported on March 13 that 5% of the topsoil and 37% of the subsoil in Kansas was short or very short of moisture and USGS streamflow was quite low in central Kansas. Yet another source of water worry in addition to groundwater rights, an increasing focus of litigation in Kansas and other states feeding off the overburdened Ogallala Aquifer. 

Flooding on the Sabine River in Southeast Texas submerged the town of Deweyvilleclosed Interstate 10 in nearby Orange, and displaced thousands as the river reached levels not seen since 1884. In Idaho federal water managers are releasing water from reservoirs above Boise to make room for snowmelt and to avoid flooding later this spring.

Forecast Breakdown
The transition from dominant water surpluses to primarily drier conditions throughout the country is evident in the 3-month maps below. Note the contrast between conditions observed in the last three months (Jan-Mar 2016) and those predicted for April through December. From April through June water deficits are forecast to emerge in much of the eastern US; the Ohio, Tennessee and middle Mississippi River basins; Northern and Central Plains; and the Southwest. Surpluses will continue to emerge in Idaho and northeastern Nevada, Colorado, along the Canadian River as it cuts through the Texas Panhandle into Oklahoma, between Amarillo and Lubbock, and near Mt. Livermore in western Texas.

From July through September, the emergence of exceptional water deficits along the Missouri and Yellowstone Rivers is clearly traced in a deep red path through the Missouri Basin. Deficits along the lower Mississippi are also evident, as is the spread of deficits in Michigan, Wisconsin, Montana, Wyoming, and the Pacific Northwest.

The forecast for the final quarter of the forecast period (Oct-Dec 2016) looks similar to the prior quarter with a few exceptions, most noticeably that exceptional deficits along the Missouri and Yellowstone Rivers are no longer evident. The emergence of surpluses is forecast in southern Colorado, along the Canadian River in northern New Mexico, and along the Rio Grande River.

Outside the contiguous US, water surpluses are forecast for south-central Alaska from Bristol Bay northward through June, surrounded by moderate deficits throughout much of the state which diminish in the fall. Moderate surpluses are in the forecast for the west end of the island of Hawai’i for much of the forecast period; deficits are forecast on Maui in May.

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

* Please note that effective March 28, 2016 NOAA changed the initialization procedure for CFSv2 to address issues with unrealistically cold sea surface temperatures in the Tropical Atlantic Ocean. As a result, this month's Watch List is based on an ensemble of 14 CFSv2 forecasts issued after this fix was implemented instead of the normal 28. For more information see http://www.nws.noaa.gov/os/notification/tin16-09cfs.htm and http://www.nco.ncep.noaa.gov/pmb/changes/downloads/CFSv2_Atlantic_cold_bias_problem.pdf.

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.

For more information contact info@isciences.com.

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