“It’s looking unlikely that this will be the wettest year on record. For most of this area, it’s likely to be in the top five,” said Trent Ford, Illinois state climatologist, as he spoke at a meeting at IllinoisValleyCommunity College in Oglesby.
The meeting was one in a series of bimonthly meetings on water resources and water supply sponsored by the Tri-County Regional Planning Commission and the North Central Illinois Council of Governments.
Ford, who took over from longtime state climatologist Jim Angel at the Illinois Water Survey, discussed climate change and how it could be impacting weather in the near and long term.
One of the major impacts that north-central Illinois residents, including farmers, already have experienced is a change in how and when rain falls.
“It really does matter not just how much rain falls but how intensely it falls, as well,” Ford said.
The trend has been toward more frequent and more intense rainfall events.
“We consider the two-inch mark and over as extreme precipitation,” Ford said.
He added that the region has seen an increase in those major rainstorms over the last two decades.
Dryness isn’t the issue for the region.
“When we talk about the entire water budget and how much water we’re getting, the problem for this region as in most of the northern half of Illinois, is too much water,” Ford said.
Ford also addressed the opposite end of the scale — drought. While water availability has been and will continue to be an issue for the desert Southwest, the Midwest has not seen the kinds of years-long droughts that have plagued the West.
Drought is measured most commonly by the Palmer Drought Severity Index, which measures surface water balance and is used to measure drought over a longer term.
The index goes from -10, extreme dry, to +10, extreme wet. Anything lower than -1 is considered drought, and anything below -4 is considered extreme drought.
Going back to 1895, Ford said the Palmer index has been below -4 nine times and seven of those were before 1965. But after 1965, the index has only gone below -4 twice, in 1988 and 2012.
Ford said the droughts that the area has experienced recently tend to be shorter in length, spanning only a single warm season or growing season.
“By the time we get to the next growing season, we are back up to the normal water standards as far as soil moisture and precipitation are concerned,” Ford said.
Again, the trend in the northern Illinois and north-central Illinois region leans toward more wet than more dry.
“The last 50 years have been significantly wetter than the previous 70 in this region,” Ford said.
The duration of droughts also has decreased in the Midwest in the last few decades.
“We’re still getting events every few years or so. It’s just they are not lasting as long as they did in the earlier record, and the maximum intensity is not staying at the maximum intensity for long,” Ford said.
Ford said he has received calls at the Illinois State Water Survey office asking if the state was “due” for another drought. While “due” may not be the right word, Ford said there is the chance that the weather patterns that changed in the 1970s, which led to the shorter-duration droughts for the Midwest, could and will change again.
“We’ve been in a phase since the 1970s that makes it less likely for the Midwest to experience these prolonged, multi-year droughts. That flip, that oscillation, does operate on these multi-decadal time scales, so it is likely at some point in the near future, as in the next several decades, that those patterns will flip back into a phase that will make it more likely for the Midwest to get some of those multi-year drought events,” Ford said.