By Carey Gillam
(Reuters) - Heavy snow and rain through parts of the U.S. South in the last week helped ease a historic drought, but little long-term relief was forecast, and drought conditions were growing worse in the west, leaving a swath of the nation in need of rain or snow.
"We're getting a dry start to the winter," said Laura Edwards, climatologist for the Western Regional Climate Center and South Dakota State University, author of this week's national Drought Monitor report
The report is a synthesis of multiple indices and impacts representing a consensus of federal and academic scientists, and reports weekly on drought conditions across the United States.
Last year, drought caused billions of dollars in damages to crops, livestock, and timber, and wildfires destroyed thousands of acres.
This year is not shaping up to be much better, at least at this early point in the season, according to forecasters. Over the next several weeks, temperatures should be warmer than normal across the southern states from Nevada across the southern and central Plains, which should negate the recent short-term moisture the region has seen, Edwards said.
"We are in a La Nina season," she said. "We are expecting a similar pattern with dry swaths across the south and wetter in the north."
The U.S. Climate Prediction Center said last week that sea-temperature data suggests La Nina will be of weak-to-moderate strength this winter, and will continue thereafter as a weak event until it likely dissipates sometime between March and May.
In the Drought Monitor report issued Thursday, Texas drought levels improved, though the state was far from recovering.
More than 62 percent of the state was still considered in "extreme" levels of drought, though that is down from 67 percent a week earlier.
The one-year period between November 1, 2010, and October 31, 2011, was the driest in the state's history, and three-month period of June to August in Texas was the hottest ever reported by any state in U.S. history, according to state and federal climate experts.
The improvement in Texas followed strong storm systems that produced more than 10 inches of snow fall across the Texas panhandle and three or more inches of rain soak the Gulf Coast over a two-day period.
Oklahoma, however, actually saw extreme levels of drought creep higher over the last reporting week, with nearly 29 percent in extreme drought, up from 27.48 percent a week earlier.
DROUGHT GROWS IN WEST
The western United States was seeing ever drier conditions as well. Continued dry conditions and "dismal" precipitation levels translated to the expansion of "moderate" drought in the central plains of Washington and northern Oregon.
Seasonal precipitation totals were 50 percent or less of normal for the last 90 days, according to the Drought Monitor report.
A significant part of California and Nevada were also too dry and suffering as a lack of notable snowfall across the western states left the Sierra Nevada area in a short-term drought, with forage conditions poor for livestock and wildlife.
"They have been building up this dry trend for awhile," said Edwards.
Data for 2011 shows some areas of California and Nevada recording one of the top 10 or 15 driest years on record, Edwards said.
Nearly 81 percent of California was rated abnormally dry, up from 70 percent a week earlier, according to the Drought Monitor report issued Thursday. More than 46 percent of the state was rated in moderate drought and 3 percent was in severe drought, the report said.
Nevada had 88 percent of the state rated abnormally dry and 33 percent rated in moderate drought.
(Reporting by Carey Gillam; Editing by Bob Burgdorfer)