Fog Blankets the Nation: A Comprehensive Overview
Widespread Fog Engulfs the United States
On a chilly Friday morning in 2024, an extensive veil of fog settled over much of the nation’s Heartland and parts of the Mid-Atlantic region. This meteorological phenomenon affected over 70 million people, with many experiencing fog alerts for at least three consecutive days.
The fog stretched from the Canadian border down to the Gulf Coast, though its coverage was slightly less expansive compared to the record-breaking national coverage observed on Thursday.
Improved Visibility and Persistent Fog Alerts
While visibility improved in some areas on Friday morning, it remained significantly reduced compared to the previous day. On Thursday, visibility was as low as 300 feet in certain regions.
Despite the improved conditions, Dense Fog Advisories continued to be in effect through midday Friday, cautioning travelers and residents about the lingering low visibility.
Record-Breaking Fog Alerts
Thursday marked a historic day, setting a record for the third consecutive day with the highest number of National Weather Service office “zone” regions under Dense Fog alerts. According to Daryl Herzmann of Iowa State University’s IEM, there were 1,517 regions under fog alerts, surpassing the previous record of 1,341 set on Wednesday.
This unprecedented stretch of fog alerts highlights the widespread nature of the weather phenomenon and its impact on a significant portion of the population.
Freezing Fog and Missing Sun in St. Louis
St. Louis experienced an unusual meteorological event, with fog and low clouds shrouding the city for nearly 90 hours, effectively blocking out the sun. The National Weather Service Office in St. Louis humorously declared the sun “missing” due to its prolonged absence.
The visibility in St. Louis remained below 2 miles for most of the time between Tuesday evening and Thursday morning, with the fog returning on Thursday night, albeit less dense.
Chicago faced a similar situation, with extended periods of fog reducing visibility to 2 miles or less. At one point, the FAA issued a ground stop at Chicago O’Hare International Airport due to limited visibility caused by the fog.
Causes of the Extensive Fog
The widespread fog was attributed to a combination of factors, including a warming trend across the nation’s midsection following a deadly arctic blast and the interaction of this mild weather pattern with frigid ground conditions.
The subfreezing temperatures in the preceding weeks had caused the ground to remain cold, creating a temperature differential with the warm air mass moving in. This led to the formation of dense fog, which acted as a blanket, preventing the sun’s heat from reaching the surface and warming the ground.
Above-Average Temperatures and Forecast
Across the United States, above-average temperatures prevailed throughout the week, with the warmest temperatures expected on Friday in cities like New York, Philadelphia, and Washington, where highs could reach into the 50s.
This significant temperature increase was particularly notable in Memphis, which experienced a dramatic shift from a high of 2 degrees on January 17 to a high of 62 degrees on Wednesday.
Conclusion
The extensive fog blanketing the nation’s Heartland and Mid-Atlantic regions posed challenges to visibility and transportation, leading to fog alerts and flight delays. The unusual meteorological event in St. Louis, where the sun remained hidden for nearly 90 hours, further highlighted the impact of the fog.
As the warming trend continues, the fog is expected to gradually dissipate, allowing the sun to shine through and bring relief to the affected areas.