Northern Illinois placed under another dense fog advisory, severe storms possible Friday

Another Dense Fog Advisory:

In a similar fashion to Wednesday, the day is starting off with a Dense Fog Advisory. This time, the advisory is for all of our northern Illinois counties, and it runs until 9AM. Visibility in these areas will fluctuate, registering less than a 1/2 mile at times. If you plan to be out on the roads during the morning commute hours, please make sure to remain focused and use extra caution. 

Once the fog fully lets up, expect a mix of clouds and sun into the afternoon. Despite a decent breeze out of the northwest, high temperatures for most will climb into the mid to upper 80s. 

Even though we see an uptick in our temperatures, today's northwest wind will help keep humidity-levels comfortable. As our next frontal boundary sinks into the region from the north, skies will turn mostly cloudy for the overnight hours. 

Friday's Severe Potential:

It's during this time in which we will have to monitor the position of the front, as well as a storm complex that develops to the west. This complex will be weakening as it approaches the Stateline, but it may hold together long enough for us to see a few showers and storms early in the day. 

While severe weather is not expected with this activity, this will play a role into the severe threat that comes about Friday afternoon into Friday night. Another factor that will determine Friday's severe threat will be the cap or "atmospheric lid" that will be present during the afternoon. This is a warm layer of air in the low-levels of the atmosphere that hinders thunderstorm develop. 

In their latest severe weather outlook for Friday, the Storm Prediction Center left all of northern Illinois and southern Wisconsin under a level 2 slight risk. Of the severe threats, straight-line winds and large hail are the biggest concerns. 

The tornado threat is low, but still present as there will be enough low-level shear (winds turning with height) in place. The associated cold front will pass through late Friday night into early Saturday, allowing dry conditions to settle in for Saturday. Despite Saturday's winds being out of the northwest, highs will climb into the upper 80s.