March 05, 2008
Winter and Spring Will Have Varying Effects on Nebraska
LINCOLN, Neb. — 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, a University of Nebraska-Lincoln state climatologist said.
Al Dutcher, a state climatologist in the university's Institute of Agriculture and Natural Resources, said this winter's temperatures have averaged 3 to 6 degrees below normal.
Heating demands also are above normal, he said. Heating degree day units, which calculate energy demand, indicate that the eastern half of the state has accumulated an average of 8 percent more heating degree day units than the 30-year normal. If temperatures continue their below-normal trend during March, heating degree day unit accumulations could easily surpass 10 percent above normal, Dutcher said.
Precipitation this spring could become a benefit or a hindrance to agricultural interests across the state depending on location.
"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."
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.
Projected snow melt from the Upper Platte River basin is projected to be above normal, but the two largest Wyoming reservoirs are around 20 percent full, he said. Most of that water will not
make its way downstream as the Pathfinder and Seminoe Reservoirs capture the snow melt. Therefore, inflows into Lake McConaughy will depend on releases from Glendo Reservoir and surface runoff from Glendo to McConaughy, he said.
McConaughy is at 38 percent capacity, compared to 32.6 percent at this time last year, which represents an additional 100,000 acre feet of water in storage, he said. Its elevation is only a foot lower than last year's peak elevation. With normal moisture upstream of the reservoir during the next two months, the lake could reach 45 percent of capacity this year before irrigation releases, he said.
"It is going to take several years of above-normal snowfall within the basin, or a 1993-style flooding event, before McConaughy ever completely returns to a normal pool," Dutcher said.
Future severe weather may be affected by the chilly winter as well. Dutcher said snowpack levels are high around the world and near record snowpacks exist across portions of the Rocky, Cascade and Sierra Mountains. With deep snowpacks across northern Canada and the Rockies, cold air sources will be available well into spring, Dutcher said.
As low pressure systems work across the U.S., larger temperature gradients could potentially be seen south and north of surface lows. These gradients could lead to an increased risk for severe thunderstorms and tornadoes, Dutcher said.
"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."
3/5/08-AB Al Dutcher
School of Natural Resource Sciences State Climatologist (402) 472-5206
 
Sandi Alswager Karstens IANR News and Photography (402) 472-3030
Department:
School of Natural Resources
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