What constitutes a drought?
The National Weather Service defines a drought as a deficiency in precipitation over an extended period, resulting in a water shortage. It is a normal phenomenon that various climates see throughout the years.
One of the ways a drought is measured is by the soil and how wet it is below the surface. Therein lies the complicated algorithm it takes to measure a drought, as there are thousands of soils across the world and each one absorbs water differently.
Missouri has about 500 different types of soil, and the components of each soil determine how long it takes for the soil to absorb water. The amount of water in the soil is known as the Palmer Drought Severity Index, which the government uses to understand what type of drought a region is seeing.
A drought doesn't happen overnight, though. National Weather Service meteorologist Steve Bays once said, "It took us a long time to get in a drought and it will not take one overnight event to get us out."
Within the last 72 hours, plenty of rain has fallen across drought-ridden Mid-Missouri, but is it enough to get us out of the drought and replenish the moisture in the soil.
To understand what constitutes effective rainfall, one must look at the soil that is within the region to understand drought relief.
In Boone County, the most common soil type is Adco Silt Loam. It makes up about 43 percent of the county and doesn't take up water well, due to its high runoff rate. So a thunderstorm that produces high rainfall amounts would not be as effective in reducing the drought as a slow-moving system that brings light rain like we saw the last several days.
The most recent information gathered for the drought monitor shows that the soil in Mid-Missouri has actually benefited from the rain and it's likely we'll see the drought improve immensely as we close the door on this week.