Summer Weather Outlook: Equal Chances Wet or Dry

Summer Weather Outlook: Equal Chances Wet or Dry

June 27, 2008

Most of Nebraska has seen above normal precipitation and below normal temperatures this summer, and July forecasts show equal chances of those trends continuing, UNL's state climatologist reported this week.

July forecasts show an eastern sliver of Nebraska — along with Iowa and Illinois — still at above normal precipitation and below normal temperatures. However, the rest of Nebraska stands an equal chance of current trends continuing or reversing, said Al Dutcher, state climatologist in the university's Institute of Agriculture and Natural Resources.

While flooding in Nebraska has not been as extreme as in Iowa and other parts of the eastern cornbelt and Mississippi River, most of the state has gone six straight months with below normal temperatures and significant precipitation, Dutcher said.

"We're at a point where we really need to see some good, dry weather," Dutcher said. "The eastern two-thirds to three-fourths of the state has a full soil moisture profile."

The wet weather slowed planting across eastern Nebraska this spring. In addition, many farmers had to get back into their fields to replant after heavy rains washed crops away or they were destroyed by winds and hail.

In Nebraska, 25% of the corn crop had emerged prior to May 18 with the next 25% between May 18 and 24, the next 25% between May 24 and 29 and the remainder after May 29.

That means only 25% of the crop emerged before normal emerging time, Dutcher said. The next 25% is one to six days behind normal with the following six to 11 days behind normal and the remainder 11 to 20 days behind normal.

"And that is in much better shape than the eastern cornbelt," Dutcher said. "If temperatures consistently run below normal, we would expect that at the earliest, we are going to see the crop come into pollination somewhere around mid-July, with 50% of the crop behind that."

The bad news is that is the state's hottest time of year.

"Because of all this moisture, if we don't start seeing periodic dry weather, we're going to have shallow rooting in our crops. A brief, intense heat wave can inflict more damage than it normally would," Dutcher said.

If all the moisture the crop needs is being supplied at the surface, there is no reason for that crop to grow roots more than a couple of feet deep. Roots need to grow down 4 to 5 feet.

"The next thing we'll have to worry about is where crops will stand as far as freeze damage," he said. "If we don't see a normal temperature trend, that is something we'll have to pay attention to."

The good news is eastern Nebraska farmers do not need to irrigate now, Dutcher said.

In addition, a lot of gravity-fed irrigators will not need any water deliveries until at least July 1.

The upper Platte River reservoir system, which flows into McConaughy, has shown a positive response to the recent weather. This means reservoirs are filling at a greater rate than at this time last year. Lake McConaughy is 1% above estimates, and it could fill up to 48% full, he said.

Above normal snowpack in combination with isolated heavy thunderstorm activity has led to strong inflows into Seminoe, Pathfinder and Glendo reservoirs in Wyoming.

However, these areas are still drier than normal.

"While we've definitely shifted toward a wetter regime than accustomed to, the Panhandle and southwest Nebraska are still in a drought," he said.

Water demands during the state's hottest and driest months of the year —July and August — typically greatly out-strip precipitation that would fall.

"Unless we see another sustained period over the next two months with below normal temperatures to keep soil moisture in the profile, I don't expect any more improvement," he said.

Dutcher said forecasts are starting to show signs of ridging across the central and northern Rockies, which could bring scattered chances of precipitation to the Great Plains region.

For more information about Nebraska drought, visit IANR's Drought Resources and Information Web page at http://ianrhome.unl.edu/drought/. To view the U.S. Drought Monitor, visit http://www.drought.unl.edu/dm/monitor.html.