ALTON - Residents in the Metro East region of Illinois experienced varying visibility conditions due to fog that developed overnight, primarily affecting areas within five to ten miles of the Mississippi River. National Weather Service in St. Louis Meteorologist Jayson Gosselin noted that the clearing of clouds from west to east allowed for low-level moisture to linger, contributing to the formation of fog in specific areas.
In Alton, near the Mississippi River, the fog was very difficult for motorists.
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The fog was not uniformly widespread, but found primarily in river valleys, the meteorologist said. For instance, southeastern St. Clair County reported minimal fog presence.
Gosselin explained that dew point measurements, which indicate the amount of water vapor in the air, played a significant role in this phenomenon.
"When the temperature hits the dew point, saturation occurs, leading to cloud formation. Fog is essentially a cloud that forms just above the surface," he said.
Visibility was notably reduced to about an eighth of a mile in some areas, prompting Gosselin to advise commuters to exercise caution.
"If you know fog is likely, plan to wake up 10 minutes early, allow extra time for your commute, and maintain a safe distance between vehicles," he recommended. He further cautioned that visibility can change rapidly, especially for drivers approaching areas near bodies of water.
As conditions improve throughout the day, residents are encouraged to remain vigilant while traveling in areas prone to fog.
