* WHAT. Visibility one quarter mile or less in dense fog. * WHERE. Portions of East Tennessee and southwest Virginia. * WHEN. Until 9 AM EDT this morning. * IMPACTS. Low visibility could make driving conditions hazardous.

Clear skies, light winds, and lingering low-level moisture are helping areas of valley fog to develop and become dense early this morning. This fog will continue to expand but likely be thickest in the valleys. Visibilities will be below a quarter of a mile at times in the worst of the fog. Be sure to slow down and use your low beam headlights when you encounter any fog.

* WHAT. Visibility one quarter mile or less in dense fog, especially in the valleys. * WHERE. Portions of south central and southeast Kentucky. * WHEN. Until 9 AM EDT this morning. * IMPACTS. Low visibility could make driving conditions hazardous.

Areas of fog can be expected in parts of the northern Cumberland Plateau, northeast Tennessee, and southwest Virginia this morning. The fog will be dense in valleys where winds are calm, and visibilities will drop below a quarter of a mile at times. Be sure to slow down and use your low beam headlights when you encounter fog.

Clear skies, light winds, and lingering low-level moisture are helping areas of valley fog to develop and become dense early this morning. This fog will continue to expand but likely be thickest in the valleys. Visibilities will be below a quarter of a mile at times in the worst of the fog. Be sure to slow down and use your low beam headlights when you encounter any fog.