* WHAT. Visibility one quarter mile or less in dense fog. * WHERE. Portions of east central Ohio, western Pennsylvania, and northern and the northern panhandle of West Virginia. * WHEN. Until 9 AM EDT this morning. * IMPACTS. Low visibility could make driving conditions hazardous. * ADDITIONAL DETAILS. Satellite imagery, web cams and surface observations show that dense fog has become more widespread across the region early this morning. Visibilities will be worst in river valleys, as well as areas south of I-70, and across northwest Pennsylvania. Rapid changes in visibility are expected, which will also lead to hazardous driving conditions. Visibilities are expected to quickly improve after 9 PM.

Areas of fog have developed over portions of northern Ohio and Northwest Pennsylvania this morning. Fog is locally dense, as low as one quarter of a mile, with the worst conditions in low valleys or higher hills of the region. Use caution if traveling, and be alert for rapid changes in visibility when encountering the dense fog.

Areas of fog, locally dense, will continue early this morning. Visibility will be reduced to a quarter of a mile or less in some locations. Use caution if traveling, and be alert for rapid changes in visibility when encountering the dense fog. The fog is expected to gradually dissipate between 8 and 9 am

Areas of fog can be expected across the region through sunrise. Some of the fog may be locally dense in spots. The shallow nature of the fog will result in rapid fluctuations in visibility over short distances. If traveling this morning, remember to practice safe driving methods such as slowing down, allowing extra distance between you and the vehicle in front of you, and using your low beam headlights. The fog is expected to dissipate between 8 AM and 10 AM.