No snow here... but ice fog?

As our family is stuck in several inches of snow, our weekend forecast is calling for "ice fog"... a condition I have never heard of. This forecast results in an "air stagnation" warning that will last for the next three days. When our Boston-pal Dave visited just before Thanksgiving, we experienced something similar and it was quite a bummer. Basically, a blanket of thick fog covered Seattle and she didn't show her face for days. On the upside, we're still wearing our autumn gear.