Issued by the National Weather Service, Philadelphia, Pa., 3:35 p.m. EST, Wed., Jan. 28, 2009
... Dense fog advisory now in effect until 8 p.m. EST this evening...
Warmer air over the cold ground covered with snow and sleet, continues to produce fog, some of which continues to be dense. Winds are expected to increase early this evening as a cold front moves through. This will help mix the atmosphere and therefore an improvement to the visibilities is expected. The visibilities have already improved across southern Delaware and into portions of Cape May County in New Jersey.
The visibilities will be reduced to near zero in some areas. Spotter reports indicated that the worst visibilities were variable, meaning that relatively better visibilities were dropping to dangerous levels in only a few feet. If you plan to drive the next several hours, slow down as visibilities will be greatly reduced and can do so over a short distance. Use your low beam headlights and leave plenty of distance between you and the vehicle in front of you.