In general, foggy conditions happen when there is enough moisture near the surface as temperatures drop. If all conditions are met, the air saturates, and fog forms. For this week on Weather Matters With Matthews, I will discuss the difference between dense and patchy fog.

Dense Fog: This kind of fog is widespread and can be found high in the mountains. If you must drive on the road, do it slowly, and distance yourself from others. It is also wise to turn on your low-beam headlights when approaching fog, so too much light does not reflect back at you.

Patchy Fog: This kind of fog is surprising. It can be clear on one part of the road, and foggy on the next. This type of fog can be found near a valley. If you must drive when patchy fog is present, be ready for sudden drops in visibility. Use extra caution on bridges and valleys because that is where patchy fog is more common and dangerous.

Fog is at its worst when visibilities are reduced to less than a quarter of a mile. Be sure to check the 18 Storm Team forecast for any possibility of a dense fog advisory.