I thought it was suppposed to be sunny today. What gives?

The forecast last night and this morning called for fog, but stated the fog would be out of here mid-morning and skies would begin to clear.  Well, it's 10:10 am and the fog is still pretty thick outside and showing no sign of letting up anytime soon.  So, what happened?  Well, there is a meteorological reason as to why the fog is sticking around longer than forecast (and it's not just because we don't know what we're talking about).

Forecast Sounding from Davenport, IA

After Thursday's rain, skies began to clear and the winds turned calmed.  With the added moisture in the atmosphere, this was a nice set up for fog development and that's exactly what happened.  This morning, however, the incoming cirrus clouds from the west have trapped that moisture near the surface.  This is evident on the morning forecast sounding from the Quad Cities office in Davenport, IA.  The green line indicates the dew point temperature and the red line indicates the air temperature throughout the atmosphere.  When those two lines are close to each other, it usually means there is some sort of saturation (moisture) present.  Whether it be in the form of clouds or fog.  When the two lines are pretty much on top of each other, this means that the atmosphere is very saturated.  There is also a little convergence (winds coming together) just above the surface which has helped keep the fog around.  Adding to that, there is a small inversion present (warmer air aloft) that is also helping to keep the fog settled in at the surface.

Visible Satellite Image
 

Looking at the visible satellite image, we can actually see where the edge of the fog is and where the clouds are present.  Some good news is that the fog has been eroding away from the east, but the bad news is the cirrus clouds continue to move in from the west.  This means areas east of Rockford will likely see a little more sun while from Rockford on westward, we may be stuck in the fog through the early afternoon.

If there wasn't any cloud cover, the fog would have had a better chance of lifting due to the help of the sun.  Since we don't have that this morning, the fog is more likely to stick around longer and make the afternoon much cooler.

A Dense Fog Advisory remains in place until Noon for Stephenson, Jo Daviess, Carroll, Whiteside and Green counties.