Air Stagnation Advisory issued December 3 at 6:38PM 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…Upper Treasure Valley.

* WHEN…For the Dense Fog Advisory, until noon MST Wednesday. 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.