I want to add to what Steve talks about below. The computer models have been trending colder so the icing threat has increased for Saturday night into Sunday. As of now, the NW parts of the viewing area (all areas North and West of St. Louis County) are under a Freezing Rain Advisory from 6pm Saturday to 6pm Sunday as accumulations are looking much more likely. At this point we could see anywhere from a glazing up to .25". Once you get to about .25" of ice, that's when you begin to see trees coming down and sometimes bringing power lines with them. Here's the caveat...if the models continue to trend colder, then it's possible the rest of the metro area will be added to the advisory. I'll keep you posted. Also, if the disturbance moving through tonight ends up being stronger, that would lead to heavier precipitation which equals greater ice accumulations.
There is rain in the forecast for the next several days which could mean several rounds of freezing rain. Our next greatest threat comes Monday night into Tuesday where many of the same areas could get hit with accumulating ice again. It's a little too early to pin this one down...we'll continue to provide you with updates.