Air Stagnation Advisory issued December 4 at 9:16AM MST until December 7 at 5:00PM MST by NWS Boise ID

* WHAT…For the Dense Fog Advisory, visibility one quarter mile or
less in dense fog. For the Air Stagnation Advisory in valleys, an
extended period of stagnant air, with light winds and little
vertical mixing. This is due to an inversion near the surface that
will continue to trap pollutants.

* WHERE…Treasure Valley Zones.

* WHEN…For the Dense Fog Advisory, until 2 PM MST Friday. For the
Air Stagnation Advisory, until 5 PM MST Saturday.

* IMPACTS…Poor air quality may cause issues for people with
respiratory problems. Low visibility could make driving conditions
hazardous.

* ADDITIONAL DETAILS…Fog could produce patchy black icy for slick
roads.