Surging temperatures and humidities in coming days will lend an ominously explosive
quality to the atmosphere. Among the risks this poses to the Midwest is the potential for
thundery interludes in which downpours generate large rainfalls—bad news for a region
still reeling from near record flooding. Just where the heaviest storms erupt is always a
dicey call for forecasters. While rising temperatures and some of the summer season’s
most humid air provide the building blocks for thunderstorms, the rain cooled air that
gushes from such storms plays a big role in determining the areas exposed to the most
prolonged bouts of rain. With the atmospheric water content headed for nearly 2 inches,
there will be plenty of moisture for any storms to tap.
The delightful low humidities of recent days are a thing of the past for the remainder of
the work week. Dew points, a measure of atmospheric moisture, are headed for the 70s
later Wednesday for only the fifth time this year. A shift in wind direction from the ground
to higher altitudes is just the sort of environment in which thunderstorms rotate and
generate gusty winds. Hail and lightning are obvious risks in this situation.
