Widespread Dense Fog Triggers Ground Stop in Chicago, Disrupting Travel

One of the biggest weather storylines for much of the country over the past few days has been the development of thick fog. A large swath of the central and eastern U.S. has been dealing with widespread fog, complicating travel on both the roads and in the air. What is responsible for this fog and when will it abate? Read on for the details of this cloudy forecast.

100 Million Americans Under Foggy Conditions

It has been a difficult week for travelers thanks to a dense layer of fog entrenched over much of the central and eastern portions of the country. As of Thursday morning, roughly 100 million Americans spread out over two dozen states were dealing with the official designation of "dense fog." According to the National Weather Service (NWS), dense fog is defined as fog that reduces visibility to a quarter of a mile or less.

The dense fog has wreaked havoc for air travelers. There were over 1,100 reported flight delays attributed to the fog as of mid-day Thursday. The fog was so disruptive across parts of the Upper Midwest that the Federal Aviation Administration (FAA) was forced to order a ground stop at Chicago's O'Hare International Airport for a time on Thursday morning.

The dense fog has wreaked havoc for air travelers. There were over 1,100 reported flight delays attributed to the fog as of mid-day Thursday. The fog was so disruptive across parts of the Upper Midwest that the Federal Aviation Administration (FAA) was forced to order a ground stop at Chicago's O'Hare International Airport for a time on Thursday morning.