Climatologists: Weather pattern is changing for the better

May 13, 2011

WEST LAFAYETTE, Ind. —After an April that brought record rainfall to much of Indiana and Ohio, climatologists agree the weather pattern is improving – a welcome change for farmers in both states.

La Niña is the weather pattern keeping much of the Midwest wet. It occurs when the surface temperature of vast areas of the Pacific Ocean are cooler by at least 1 degree Fahrenheit, said Ken Scheeringa, associate state climatologist for the Indiana State Climate Office, based at Purdue.

"The La Niña that began last summer is now weakening and is expected to disappear by the end of June," he said. "However, impacts of La Nina will continue over Indiana and Ohio as long as into August because of the natural 2-3 months lag time for the atmosphere to respond to ocean temperature changes."

While La Niña's effects will linger, Scheeringa said the weather will continuously improve to more favorable planting conditions as the month of May continues.

"Farmers will get to plant their crops," Scheeringa said. "As La Niña slowly dies out, the opportunities for growers to get into their fields are coming – especially as May progresses. So, even though the situation seems desperate now, particularly in southern Indiana where some fields are still submerged, it will improve."

As of May 8, only 4 percent of Indiana's corn crop and 2 percent of Ohio's was planted, according to the U.S. Department of Agriculture's National Agricultural Statistics Service. Nationally, 40 percent of the corn crop was in the ground – 27 percent more than a week earlier.

With weather more suitable for planting, those statistics could soon change.

In the May 10 issue of Ohio State Extension's C.O.R.N. Newsletter (http://corn.osu.edu), Jim Noel of the National Weather Service in Ohio predicts the rest of May will see improved conditions. Normal temperatures for the next few weeks consist of average highs near 75 degrees and lows near 50. Normal rainfall totals average 1 inch per week. Here is Noel's weather outlook for the remainder of May:

* Through May 16: Temperatures will average about 2-4 degrees above normal, with rainfall above normal. Rainfall will be more scattered and variability will be much higher because of the warmer late-spring weather pattern. Variability means some areas may receive 0.5 inches of rain while others receive more than 2 inches.

* May 17-23: Temperatures will average near normal and rainfall near to below normal.

* May 24-31: Temperatures will average at least 5 degrees above normal as a large dome of high pressure builds into the Southeast and parts of the southern Ohio Valley, shifting the heaviest rains into the western half of the corn and soybean belt. But the rainfall outlook is highly uncertain, depending on the strength of the high-pressure system. If it is weaker, there will be rain systems across much of the corn and soybean belt. If the high pressure is stronger, it will be drier in the eastern half of the region.

As the weather improves, improvement in soil condition will vary widely from field to field, Purdue Extension agronomist Tony Vyn said.

"In addition to rainfall totals and other weather conditions, there are many factors that determine soil drying rate," Vyn said. "Soil type, drainage, residue cover quantity and distribution, prior tillage operations, how level or rough the soil surface is, crop rotation and duration of ponding all play a role.

"For some farmers, soil conditions could be ready for planting a matter of days after the rains stop, but for others it could be longer than a week – even with no additional rain."

With a consecutive 7-10 day period of no rainfall, Vyn said corn farmers could have more than 50 percent of acreage planted by May 16.

Writer:  Jennifer Stewart, 765-494-6682, jsstewar@purdue.edu

Sources:  Ken Scheeringa, 765-494-8105, kens@purdue.edu

                   Tony Vyn, 765-496-3757, tvyn@purdue.edu

                   Jim Noel, 937-383-0527, james.noel@noaa.gov

Ag Communications: (765) 494-2722;
Keith Robinson, robins89@purdue.edu
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