The stock Grabbers are just plain lousy in anything wet,damp or moist.
Traction was lousy when there was a heavy dew on the ground.
I just put on a new set of Dunlop Rover RVXT's before the snow fell a couple weeks back and I have to say that they hold their own in the snow and slush, but not the greatest in icy conditions.
We had a good dump of @ 10inches last week and had no problems. Even my wife commented on how well the new Pathy handled in the snow (and that never happens).
They're classed as a on/off-road mud/snow tire here in Canada.
I also agree with bigmankz's recommendation if you want a true snow tire. I had a set of Nokian Hakka's on my Montana minivan and those tires held true in any condition. Pricey, but well worth it.