Update: The fog has dissipated across northern Illinois, however, humidity will linger into this afternoon and evening. Skies remain sunny and dry through the end of the day. Tonight we cool to around 60 degrees. With the leftover moisture hanging around the area, areas of fog will be possible again tonight and into Friday morning.
We are waking up to pea soup in northern Illinois. Dense fog is widespread and will slow things down for the morning commute. A combination of high relative humidity and calm wind is resulting in the thick fog. Take care on the roads and be sure to use those headlights! A Dense Fog Advisory is in effect until 9 AM this morning for visibility less than a quarter of a mile.
Even after that advisory lifts, fog will likely linger in some spots until late morning. This is because there is no major forcing to help the fog dissipate. Typically, either a breeze kicks up and helps the fog clear, or as temperatures warm, relative humidity drops and the fog clears. Temperatures, however, will be slow to warm this morning. Some spots of fog possible until as late as 10 AM or even 11 AM.
Come lunchtime, the sun will come out and then temperatures will quickly warm up. We reach the low 80s this afternoon and stay fairly humid.
Dress in layers this morning and give yourself a few extra minutes heading out the door if you can.
-Meteorologist Viki Knapp