With the wet ground from the rain earlier today, and then skies clearing, dense fog has formed over Alabama tonight.
KBHM 260453Z 00000KT 1/4SM R06/1000V1400FT FG VV001 06/06 A3036 RMK AO2 SLP282 T00610061=
The visibility at BHM airport is 1/4 mile, and in some places it is lower than that. The vertical visibility (VV001) is 100 feet, so landing a plane is nearly impossible. With calm winds and radiative cooling (the skies are clear just above the shallow fog layer at the ground), visibilities will stay low through early morning, and may drop to 1/8 mile or lower in some locations, especially valleys. Avoid driving if possible, and if you have to, use common sense.
A weak gravity wave moved over BHM over the past couple of hours too. Check out the pressure trace at Helena.