By Robert Pore
robert.pore@theindependent.com

"Soil across central and eastern Nebraska has benefited from bountiful moisture last August, September and December," he said. "Unfortunately, the Panhandle, as well as portions of southwest and west central Nebraska, have below-normal soil moisture levels."

Dutcher said future weather conditions for Nebraska depend on how long this winter's unseasonably cold temperatures remain and the amount of precipitation in the coming spring months.

He said more moisture would be welcome for drought-plagued western Nebraska, but would increase flooding risks for the remainder of the state.

"There doesn't seem to be anyone caught in the middle," Dutcher said. "You're either exceptionally dry or exceptionally wet."

Dutcher said he expects planting delays across central and eastern Nebraska if normal- to above-normal moisture falls during April and May.

"Unfortunately, if western producers expect to see significant relief from their long-term drought, their eastern counterparts will have to endure muddy fields," he said.

Dutcher said that as low pressure systems work across the U.S., larger temperature gradients could potentially be seen south and north of surface lows.

He said these gradients could lead to an increased risk for severe thunderstorms and tornadoes.

"Our peak season (for severe weather) is late April through early June," Dutcher said. "If the trend of large-scale severe weather outbreaks that dominated the past 30 days continues, then we can expect to see exceptionally active weather across the central plains this spring."

As weather patterns change, researchers have been looking in more detail at widespread damage to plants from a sudden freeze that occurred from April 5 to April 9 in 2007. The freeze was even more serious because it had been preceded by two weeks of unusual warmth.

The authors of the report, Lianhong Gu and his colleagues at the Oak Ridge National Laboratory and collaborators at NASA, the University of Missouri, and the National Oceanic and Atmospheric Administration, found that the freeze killed new leaves, shoots, flowers, and fruit of natural vegetation, caused crown dieback of trees, and led to severe damage to crops in an area encompassing Nebraska, Maryland, South Carolina, and Texas. Subsequent drought limited regrowth.

In Grand Island, the National Weather Service in Hastings reported that on April 7 the morning low was 17 degrees and on April 8 the morning low was 13, both days about 20 degrees below normal averages for that time.

While drought hit much of the South, Nebraska had a particularly rainy season in 2007, with Grand Island's precipitation for the year at nearly 40 inches.

Also, prior to the early April freeze, temperatures in late March and the first two days of April were averaging more than 20 degrees above normal.

The researchers found that rising levels of atmospheric carbon dioxide are believed to reduce the ability of some plants to withstand freezing, suggesting that global warming could lead to more freeze-and thaw-fluctuations in future winters.

According to the researchers, the 2007 freeze is likely to have lasting effects on carbon balance in the region.

They found that plants cannot absorb nutrients from dead tissue that would normally be remobilized within the plants in the fall, so many nutrients became less available for plants in 2008.

Wildlife is expected to have suffered harm from lack of food, and changes to plant architecture could have long-term implications.

Gu and his colleagues propose that the 2007 spring freeze should not be viewed as an isolated event, but as a realistic climate-change scenario.

They said that further study of its long-term consequences could help refine scenarios for ecosystem changes as carbon dioxide levels increase and the climate warms.