Arlington County and much of the D.C. area is under a dense fog advisory through 7:00 a.m. Thursday.
From the National Weather Service:
… DENSE FOG ADVISORY IN EFFECT UNTIL 7 AM EST THURSDAY…
THE NATIONAL WEATHER SERVICE IN BALTIMORE MD/WASHINGTON HAS ISSUED A DENSE FOG ADVISORY… WHICH IS IN EFFECT UNTIL 7 AM EST THURSDAY.
* VISIBILITIES… ONE QUARTER MILE OR LESS AT TIMES. WHERE THE VISIBILITY ROSE EARLY IN THE EVENING… IT IS EXPECTED TO DROP AGAIN DURING THE LATE EVENING.
* IMPACTS… AREAS OF DENSE FOG WILL CAUSE SUDDEN REDUCTIONS IN VISIBILITY AND RAPIDLY CHANGING TRAVEL CONDITIONS.
PRECAUTIONARY/PREPAREDNESS ACTIONS…
A DENSE FOG ADVISORY MEANS VISIBILITIES WILL FREQUENTLY BE REDUCED TO LESS THAN ONE QUARTER MILE. IF DRIVING… SLOW DOWN… USE YOUR LOW-BEAM HEADLIGHTS… AND LEAVE PLENTY OF DISTANCE AHEAD OF YOU.