Why So Humid? Blame It On The Corn

T24_uppermissvlyAfter a few rounds of showers and thunderstorms to start the week, including Monday Morning’s damage inducing derecho, the heat will return.  That’s never a good prospect this time of year, because extremely high dew points are possible.  The graphic to the left shows the National Weather Service forecasted highs for Sunday.  You can see most of the state will top the 90 degree mark.  And this is only the beginning.  A genuine heat wave could take hold across the state next week.  Something to keep an eye out for.

On top of that, dew points across the area could reach the mid to upper 70’s.  That’s going to make it feel downright oppressive outside.  So why is it that around the same time of year we see these high dew points?  The answer lies in the fields that made Iowa so famous.  Corn.

Corn plants are getting pretty tall by now, over 6-7 feet in fact.  Those plants “sweat.” And that moisture evaporates back into the air, raising the humidity levels over Iowa.  It’s a process called evapotranspiration. This process can allow dew points to soar across Iowa into the 80’s at times.  At this coming week will be a terrible time for something like that to happen.  Parts of Iowa next week could see the heat index top the 110 degree mark, making for very dangerous conditions outdoors.

As for thunderstorms, the only threat for severe weather here in Iowa may come late Friday night and early Saturday morning.  That’s when storms may trickle into the northern part of the state.  At this time the severe risk is low but we’ll continue to monitor the latest information.  Otherwise the big story in the coming days will be the heat, the humidity and all the problems the two will bring when they combine.

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