We've had some fog to deal with the past couple of mornings and we'll likely see fog redevelop late tonight/early Friday morning. The image on the left is a forecast sounding (snapshot of the different layers of the atmosphere) from Davenport, IA Wednesday evening. The red line indicates the temperature profile while the green line is dew point. What I want you to notice is how the temperature (red line) increases with height above the surface. This is called an 'inversion' and means that the temperatures above are warmer than what they are at the surface. Also notice how the temperature and dew point line are close together below the inversion and then move further apart higher in the atmosphere. With the lines close to each other like that, it's a pretty good indication there is moisture 'trapped' in the lower levels of the atmosphere and that's why we've got the fog this morning. Unfortunately, the inversion is a pretty strong one and looks to stay with us through early afternoon. This may cause the clouds to be slow to leave today which could keep temperatures down into the lower 50s. Gusty southwest winds may allow a little bit of the drier air above to mix down to the surface which will help skies become at least partly cloudy.
The cloud cover and fog will probably return tonight but we should see more sunshine Friday afternoon.
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