Flight Dentent,
Good discussion, BFS Grad stated in so much as we (U.S.) don’t have any official announcement of “Low Vis” Ops in effect. But if the Weather is below 800-2 there are different hold short lines one must stop at to protect the ILS clear zones. I will provide a photo of the Cat 2 Hold line that we have to stop at if the wx is below 800-2. In the case of this incident in Austin, there was a Cat 2/3 hold short line on the other side of the runway, probably because that’s where the localizer antenna was located. On the side where SouthWest lined up, there was none because the localizer beam would not be affected by holding short of the runway at the normal hold short line.
The lines closest to the aircraft are the Cat 2 (also used for Cat3 ) hold lines. We hold short of this line when wx is 800-2 or lower. We are expected to know this, and no announcements are necessary.The line closest to the runway is the normal Hold line. Hope this helps.