Weather Word Wednesday: Overrunning

Published: Oct. 11, 2023 at 10:22 AM CDT|Updated: Oct. 11, 2023 at 11:49 AM CDT
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QUAD CITIES, Iowa/Ill. (KWQC) - If you were to open up the NOAA glossary to overrunning, you would find that the definition is “a weather pattern in which a relatively warm air mass is in motion above another air mass of greater density.”

Essentially this is warmer air moving over colder air, leading to widespread precipitation, whether it is rain or snow.

As an advancing warm front approaches a relatively cool air mass, the warm air is forced upwards and “overruns” the denser, colder air.

As that happens, the rising motion of the warmer air cools down, condensing and creating clouds and precipitation, whether it’s rain, freezing rain, sleet or snow.

Eventually farther ahead of the warm front, the overrunning air cools down enough to where clouds and precipitation can’t form.

While widespread severe weather is not typically associated with overrunning precipitation events, there can be a few that produce large hail, due to the colder air above the warmer air (sharp change in temperature).

Rainfall we will be experiencing the rest of this week into the weekend won’t be a “classic” overrunning event. Most overrunning rain events happen during the late fall, winter, or early spring months.