Defining "free air levels"

I still don't understand what exactly that means, even after reading these reports for too long. As an example, can someone please translate this for me (from this afternoon's NWAC weather report): <br><br>"except snow levels locally lowering to near the surface Cascade east slopes and passes later Saturday, rising to near free air levels Sunday morning"<br><br>another example would be:<br>" 9000 ft N, 10,000 ft C, 11,000 ft S Wednesday night and <br> early Thursday<br> 7000 ft N, 9000 ft C, 9500 ft S later Thursday morning<br> 3500 ft N, 4500 ft C, 6000 ft S mid-late Thursday afternoon<br> 2500 ft N, 3000 ft C, 3500 ft S Thursday night<br> 2500 ft N, 3000 ft S early Friday, except snow levels <br>locally near the surface lower terrain Cascade passes Wednesday <br>afternoon through Thursday morning, rising to near free air <br>levels mid-day"<br><br>Can anyone help?

"free air levels" would be the normal freezing level. But there could be a pocket of cold air east of the mountains - an inversion. So locally (e.g. in the passes, where the cold air will pour through from the east) the freezing level will be much lower.<br>Might not always mean snow though... could be freezing rain or ice pellets if the air above the cold air is warm enough to have liquid precip.