Drought is Back in Illinois

Persistently dry conditions and summer-like temperatures have pushed parts of the state in moderate to severe drought. Drought impacts and condition reports are critical as drought conditions evolve in coming weeks. Please consider reporting what conditions look like in your area using the CMOR system: go.ilinois.edu/cmor.

Current Conditions

Following a top 5 wettest July in Illinois, the tap shut off in August and the first half of September. Most of southern Illinois and parts of northeast and western Illinois have seen less than 2 inches of rain since August 1st, between 2 and 4 inches below normal (Figure 1). At the same time, heat in late August and persistently above normal temperatures in September have worsened dry conditions through more evaporation.

Figure 1. Precipitation across Illinois over the last 30-days ending on September 11th. Maps show (left) 30-day precipitation totals and (right) departures from normal precipitation.

The U.S. Drought Monitor greatly expanded drought and abnormally dry conditions across Illinois in their September 10th update. Roughly 77% of the state is abnormally dry, 20% of the state is now in at least moderate drought, and parts of Alexander, Union, Pulaski, and Massac Counties in southern Illinois are in severe drought (Figure 2).

Figure 2. U.S. Drought Monitor map and statistics as of September 10th (released on September 12th).

Drought Impacts

Drought in mid-September is decidedly different than drought in mid-July, but nonetheless impactful. Agricultural impacts from our current drought situation include deteriorating pasture conditions, moisture stress and potential yield loss in soybeans and late planted corn, and stress from disease and insect pressure that are made worse by dry conditions. The dryness does help progress crop dry-down and timely harvest; however, dry conditions also increase fire risk in fields and adjacent ditches.

This is the time of the year when we typically see the lowest streamflow levels around the state, and the recent dryness has pushed levels and flow well below normal in many streams. The drought affecting Illinois is much worse in Ohio, West Virginia, and eastern Kentucky, and has significantly declined Ohio River flow. Because the lower Mississippi River (south of Cairo) greatly depends on water from the Ohio River, levels along the Mississippi have once again dipped below low stage, threatening barge traffic and other activities along the big river.

Drought impacts and condition reports are critical as drought conditions evolve in coming weeks. Please consider reporting what conditions look like in your area using the Condition Monitoring Observer Reports system: go.ilinois.edu/cmor.

Outlooks

For the second time this year, Illinois may be getting some drought relief from tropical systems. The remnants of Hurricane Francine are forecasted to bring substantial rain to the mid-Mississippi Valley and lower Ohio Valley, including 7-day forecasts of 2-3 inches in southern Illinois (Figure 3).

Figure 3. National Weather Service 7-day precipitation forecast for September 12-19.

The rainfall would be greatly helpful to reducing drought conditions, but more consistent rain is needed in coming weeks to completely assuage concerns of fire and low flow along the major rivers. The Climate Prediction Center’s most recent outlook is bullish toward wetter conditions in Illinois in late September. So, hopefully this current drought is a short-lived problem.