DEKALB, Ill. — A local weather station shows that soils in the DeKalb County area are only slightly drier than normal, despite a prolonged drought in August. But snowfall in the winter months ahead will be an important indicator of whether dry conditions continue or abate.
“This part of the state has been trying to decide whether or not it’s going to go into drought pretty much since July,” said Illinois State Climatologist Trent Ford.
Ford gave some insight as to what farmers and weather watchers should be looking out for in northern Illinois into late fall and winter.
Northern Illinois has carried some dryness from August into the early fall, but not in extreme amounts. While central Illinois into southern Illinois continue to show areas that are abnormally dry to having moderate drought, according to the Oct. 27 U.S. Drought Monitor, northern Illinois has so far escaped that fate.
“It has been drier than average across that I-88 corridor and including Carroll, Lee, DeKalb, Kendall and southern Kane counties and then into DuPage and Cook. It’s been drier than average out to about four months now, but the actual anomalies are not that large,” Ford said.
He said that due to the pattern of rainfall, there may be isolated areas that are much wetter or much drier.
“It becomes so spotty that there are fields that missed out on some of the heavier rains that may be closer to 4- to 5-inch deficits of rainfall from the average and there are going to be fields that hit all of the big rains and are probably a 2- to 3-inch surplus of moisture,” Ford said.
Local sensors at the Illinois Climate Network’s DeKalb station show the area to be about average for moisture.
“Actual observations in the ground sensors for soil moisture at the DeKalb station, its soils are right at average, if not slightly wetter than average at 2 and 4 inches. It’s just slightly drier than average at 8 inches,” Ford said.
He noted that deeper, at around 20 inches, the soils are only a couple of inches less wet than they normally would be at this time of the year.
Going into the late fall and winter, Ford said it will be important to track snowfall and precipitation.
“We want to stay with precipitation. It will be important this winter to get a near normal or wetter than normal winter as far as total precipitation,” he said.
An ideal scenario will be one in which snowfall occurs, followed by a slightly warmer period that allows surface thawing.
“If we get significant snowfall and we can get those events where it snows and then over a period of days or weeks it melts, and then you get your next snow, that snowmelt does tend to infiltrate into the soil, especially if you can get a number of days above freezing, where the topsoil can thaw a little bit,” Ford said.
Right now and until early March, soils are at a recharge stage and drought isn’t likely to intensify in wintertime.
“We are pretty much at a net gain at this time. This is kind of the recharge stage that we need to make up water that we lost over the summer,” Ford said.
The time of concern will be going into the new year and the first part of 2021, especially if there hasn’t been significant snowfall in early winter.
“My key concern would be if we get deep into January, February and we are seeing the same deficits that we are seeing now or slightly worse deficits, so if we string together a very dry November, a very dry December and then we get halfway through January and we are still very dry, I would begin to get concerned that we may carry drought into the growing season,” Ford said.
After March, as plants come out of dormancy and temperatures rise, it can be difficult to make up for existing drought from the previous fall.
“If we don’t recharge, if we don’t make up for some of that moisture deficit in the winter, like we normally do, we could carry over the drought into the next growing season. Once crops start go to into the ground, once plants start to wake up and temperatures start to rise, that will inevitably result in an increase in drought severity,” Ford said.