The Big Picture
Moderate to exceptional water surpluses are forecast to persist in southeast China, as depicted in the 12-month map below. Moderate to exceptional deficits are forecast for northeast China, exceptional deficits in Mongolia, and both deficits and surpluses are forecast in western regions of China including the Tibetan Plateau.*

Impacts
China's state flood control authority is warning of massive spring flooding, comparing the potential to the El Niño of 1997/98 which caused flooding that lasted two months, affected 220 million people in 24 provinces, and killed over 3,000. Those warnings include the Yangtze River in Southeast China. Heavy rains have already hit Guangdong, Guangxi, Hunan, Jiangxi and Fujian. The water level in the Gan River, a Yangtze tributary in Jiangxi, measured up to 2.52 meters above its safe limit and mudslides closed a section of highway. China's largest freshwater lake - Poyang Lake in Jiangxi - is 1.6 meters higher than average. According to the Ministry of Civil Affairs spring flooding has left 48 dead or missing and cost 1.21 billion yuan (US$253.5 million) in direct losses.

Forecast Breakdown
Surpluses are expected on the Yangtze River in April and on the Yellow River in June. Though surpluses are forecast to persist in southeast China – with the exception of Hainan – for the next few months, as evident in the 3-month maps (below), they are expected to diminish in Guangxi and Guangdong (see Jul-Sep 2016) and then transition to moderate deficits across the southeast in the later months of the forecast.

Widespread and exceptional deficits are forecast in eastern and southern Mongolia April through June. Deficits of lesser severity may persist throughout Mongolia, but particularly in the south, for the remainder of the forecast period.

Deficits may emerge in Hokkaido and northern Honshu, Japan in April, and surpluses in southern Honshu. Deficits are forecast in central and southern Honshu from July onward.

(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.

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