By Carey Gillam
Dec 13 (Reuters) - Drought continued to expand through many key farming states within the central United States in the past week, as scattered rainfall failed to replenish parched soils, according to a report issued Thursday by state and federal climatology experts.
Drought conditions were most pervasive in the Plains states, including in top wheat producer Kansas, according to the Drought Monitor report.
Fully 100 percent of Kansas was in at least "severe" drought as of Tuesday, up from 99.34 percent a week earlier, according to the Drought Monitor, and almost 78 percent remained in at least "extreme drought," the second-worst level of drought.
Conditions in Nebraska were unchanged, with 96.15 percent of the state in extreme drought, while the situation worsened in Oklahoma, where the percentage of the state in at least extreme drought increased to 90.92 percent from 90.56 percent a week earlier.
Texas drought conditions also worsened over the last week, with more than 32 percent of the state in at least extreme drought, up from 27.40 percent a week earlier, and more than 65 percent in at least severe drought, up from 59.27 percent, the Drought Monitor report said.
Overall, roughly 61.87 percent of the contiguous United States was in at least "moderate" drought, a slight improvement from 62.37 percent a week earlier.
The portion of the contiguous United States under at least "severe" drought expanded, however, to 42.59 percent from 42.22 percent.
Roughly 63 percent of the new winter wheat crop that U.S. farmers planted in the fall is in drought-hit areas, with the hard red winter wheat belt - especially from South Dakota to Texas - remaining deeply entrenched in drought, according to the U.S. Department of Agriculture.
Extreme temperature fluctuations from warmer-than-normal to freezing conditions have stressed the crop, which already was in poor shape due to lack of moisture.
A developing storm over the Southwest is forecast to drift northeastward, reaching the western Corn Belt by Saturday and the Great Lakes region on Sunday, according to USDA meteorologist Brad Rippey.
Storm-total precipitation could reach 1 to 2 inches in the mountains of the Southwest, but only light rain will fall on the central and southern Plains, Rippey said. Slightly heavier precipitation, locally in excess of a half-inch, will fall during the weekend across the upper Midwest, he said.
(Reporting by Carey Gillam in Kansas City; Editing by Lisa Von Ahn)