April 17, 2003

LINCOLN, Neb. — Snow and rain have improved soil moisture statewide and recent weather trends look promising, but it's too soon to celebrate an end to drought, the University of Nebraska state climatologist said.

For about the past six weeks, weather patterns have fluctuated dramatically, bringing wide temperature swings along with precipitation, said Al Dutcher, state climatologist in NU's Institute of Agriculture and Natural Resources.

"We have seen a significant precipitation event move across the state about once a week," Dutcher said. "That trend seems to be continuing, but how long it continues is the question."

This moisture has brought precipitation for the year to normal to slightly above normal across the Panhandle and the southwestern corner of the state. South central, central and north central Nebraska are between 50 percent and 70 percent of normal, while precipitation since Jan. 1 for the eastern third of the state is between 50 percent and 90 percent of normal.

If current patterns continue through June 1, the state's crop producers will have enough moisture, irrigation demands will decrease and pastures will receive much needed relief, Dutcher said.

Soil moisture across most of Nebraska is about the same or slightly ahead of least year at this time. However, in central Nebraska, levels are lower than they were a year ago. The soil moisture profile in most of eastern Nebraska is 30 percent to 50 percent full and the rest of the state is 20 percent to 40 percent full.

"We like to have the soil profile at about 80 percent full by June 1," he said. "That would guarantee enough moisture to get through a two-week dry period with minimal stress."

Recent moisture has been beneficial but, some trends could point to problems.

"We need to note that last summer it was fairly wet most of May until it turned hot and dry last summer," Dutcher said. "Also, there have been some ominous temperature changes from record cold to record heat. It's a concern to see heat building this rapidly this early in the year."

If a trough of cold air drops through the state in early May, it could set up the possibility of a late freeze, Dutcher said.

"When it's 90 degrees one day and in the 30s and 40s the next and in some places lows in the mid-20s, a pattern like that in a couple of weeks could cause some problems."

Temperatures in the 80s in early spring give people a false sense of security, he said. The average date of the last hard freeze generally falls between now and April 30.

Recent precipitation also boosted stream flow predictions, Dutcher said. The Natural Resource Conservation Service recently issued its final snowpack and stream flow estimates.

"Stream flow projections are 30 to 35 percent better than they would have been without the recent snow storm in the Rockies," he said.

Southeast and south central Wyoming received adequate snowfall, but not as much as central Colorado, Dutcher said. Most locations received 1 to 3 feet of snow, but this likely will translate into a small boost for runoff into the North Platte River.

"At this time it is unclear whether significant increases will be noticed in Nebraska since Wyoming reservoirs have tremendous storage space available to capture runoff," he said.

"Also, reservoirs are sitting considerably lower than last year," Dutcher said. "Even with the increased water in the snowpack, projections at maximum capacity are going to fall short of last year. Last year's drought pulled down those reservoirs. Also, a portion of that snow melt will be lost to infiltration because it is so dry."

As of April 1, the upper North Platte basin had 97 percent snow water equivalency, which was 148 percent of last year. The snow water equivalency is how much water is in the snowpack. Stream flow projections in the basin range from 71 percent to 76 percent of normal for this season.

The lower North Platte basin had a snow water equivalency of 95 percent of normal, which also is 148 percent of last year. Projections within the lower basin range from 24 percent to 74 percent of normal.

The South Platte basin had 114 percent of normal snow water equivalency. That is an increase of 35 percent from March 1, Dutcher said. Within the basin, stream flows are expected to be 42 percent to 102 percent of normal this year.

Lake McConaughy, which is fed by the North Platte River, is at 801,000 acre feet or 46 percent of normal, according to the Central Nebraska Public Power and Irrigation District. It is projected to peak at 815,000 acre feet on May 1.

Stream flow predictions through August for the Central Nebraska Public Power and Irrigation District call for a full 15-inch irrigation allocation.

Normal precipitation and temperatures could help extend the water allocation and keep McConaughy at around 500,000 acre feet. However, if there is a repeat of last year's drought, McConaughy could drop to 300,000 acre feet – the lowest level since the dam was being filled. The lake ended last year at 360,000 acre feet after beginning the season at 1.1 million acre feet.

The Republican River Basin will not receive relief from the Colorado snowstorm.

"The only thing that could help that basin would to be if heavy thunderstorms would produce localized flooding," Dutcher said. "There will be significant water limitations to irrigators."

4/17/03-SA

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 Resource Sciences