By Carey Gillam
(Reuters) - A series of rain showers helped ease drought conditions in parts of the United States over the last week, but drought expanded slightly in parts of the U.S. Plains, according to a report issued Thursday.
Officials in north-central Oklahoma declared a state of emergency due to record low reservoir conditions and public and private interests throughout the central United States hardest hit by drought were examining measures to try to cope with ongoing drought.
Roughly 58.87 percent of the contiguous United States was in at least "moderate" drought as of January 15, an improvement from 60.26 percent a week earlier, according to a "Drought Monitor" report issued Thursday by a consortium of federal and state climatology experts.
But severe drought blanketed 87.25 percent of the High Plains, up from 86.20 percent the week before, and 61.27 percent of the region was classified in extreme drought, up from 60.25 percent.
Fully 100 percent of the land area in Kansas, Colorado, Nebraska and Oklahoma was engulfed in severe drought or worse, according to the Drought Monitor.
While the Plains remained parched, southern portions of the Midwest received heavy rainfall during the past seven days. The Drought Monitor report said substantial precipitation was concentrated over southern Illinois, Indiana, western Kentucky, and southeastern Missouri with totals ranging from two to five inches.
The U.S. drought, considered the worst in 50 years, continues to stress winter-seeded crops such as hard red winter wheat and has caused shipping problems on Midwest rivers for a range of commodities.
Twelve to 18 inches of precipitation, or three to five times more than normal, is needed in the western Corn Belt to ease soil dryness after last summer's drought, according to Don Keeney, a senior agricultural meteorologist with Cropcast weather service.
Last summer's extreme weather locked two-thirds of the U.S. continental land mass in severe drought, cutting production of the biggest crop, corn, by 27 percent from early-season estimates.
(Reporting by Carey Gillam in Kansas City; Editing by Chizu Nomiyama)