Update on the Midwest Drought

Drought is an insidious thing.  Even though it seems like it might be a single season event, the depletion of subsurface moisture can take years to be replenished.  Apparently, a big part of the annual replenishment of subsurface soil moisture are fall rains and winter snows.  However, if the soil is particularly dry it cannot absorb moisture.

This seems counter intuitive, but think about a sponge.  A bone dry, hard sponge does not instantly grab and hold moisture as well as a slightly moist sponge.

Here in eastern Iowa the drought picture has improved markedly.  The area considered to be in “exceptional” drought, which is the worst category, has declined to virtually zero from a high of over 5% during the summer.  The next worst category of “extreme” drought has declined from a high of over 55% to slightly more than 11%.  Here are the numbers for all drought categories for the Midwest:

Watch the red splotch decrease substantially in this graphic from the U.S. Drought Monitor:

What this means is that the ground has started to recapture some subsurface moisture prior to the freeze of winter.  During the winter months, snowmelt will just run off but when spring comes the ground needs some moisture present to really absorb the spring snowmelt.  Otherwise the ground is just like a hard sponge and a lot of subsurface recharging will be lost.  Going into the summer with a deficit is a bad place to be.

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