The latest US Drought Monitor map shows moderate drought in western and southwestern Illinois, based primarily on below-normal precipitation over the past three months. Are we in moderate drought? I think it’s premature to declare drought in Illinois.
While it has been dry this winter, the demand on water supplies and soil moisture are very low in winter. In an average winter, we have more than enough water to satisfy demand – in many cases too much water. As a result of low water demand, the impacts of below-normal precipitation on water supplies, navigation, and agriculture are harder to find in winter.
The US Drought Monitor is a valuable tool for monitoring drought. However, it has many weaknesses and should not be the sole determination of drought. Here are some rules of thumb for using the Drought Monitor in Illinois.
- The Drought Monitor struggles the most during the colder months of the year for reasons mentioned earlier.
- The Drought Monitor works best in Illinois during the growing season when the impacts are most clear. Even then, there is a constant tension between declaring drought too early or too late.
- The improved hybrids of corn and soybeans have made it harder to relate heat and dryness to yield loss. As a result, the Drought Monitor may be too aggressive in declaring drought in summer.
- The Drought Monitor does not work well for water supply droughts until you reach the more severe levels (D3, D4).
Back to the current situation
There are some things we are watching right now. Some streams are running below normal in western and south-central Illinois with no impacts on water supplies or navigation yet. Soil moisture looks fine in our Water Survey network. However, the last USDA NASS report at the end of February showed drier soils in parts of western and southwestern Illinois, but that was before the recent round of rains.
If it remains dry over the next two to three months, we will start to see impacts on agriculture. But that’s true of any spring. The good news is that the next two weeks look promising for precipitation in Illinois.
Let me know of any impacts that you are seeing, especially in western and southwestern Illinois from the dry winter. Thank you.