AWD and 4WD are not the Solution to Everything.
By distributing the drive force (and traction requirements) among all four wheels, your vehicle might not start to slip 'n' slide as quickly.
Similarly, engine braking works on all four wheels and thus might be more effective than two-wheel engine braking. Or not. Depends on many variables. Don't depend on it.
So much for the good stuff. Here's the downside:
Less feedback. With all wheels driven, the vehicle really is more stable (a Good Thing), but it doesn't tell you when it's getting slippery. Sometimes when you find out, it's already too late.
Overconfidence. "Hey, I've got AWD. I can conquer the world." No, you can't. And when things (and your car) go sideways, it very well could be much worse than it would have been if you had lost traction sooner in 2WD. Or if you had felt a little loosey-goosey and slowed down.
With traditional 4WD, less stability, less steering accuracy. A traditional (part-time) 4WD system generally forces the drivetrains at both ends of the vehicle to turn at the same speed. When this condition prevails, it means that at least one tire at one end must slip when going around a corner. Which tire this will be and how badly it will affect the stability of your vehicle is unpredictable. The two-door Jeep Wrangler is especially miserable. The short wheelbase and high center of gravity combined with a part-time 4WD make it especially prone to forgetting which way it's supposed to be going at speed on a slippery surface. The Jeep is awesome off-road and in the mud. On slippery highways, not so much.
And finally, with AWD or 4WD, when you finally get stuck, you're really stuck. Enjoy whatever happens next, like calling a wrecker (who is busy and will be there in 3 hours) or digging around your wheel wells so you can crawl underneath in the snow and wet and install your chains, if you have them.
Tires. All-season tires aren't. They are spring-summer-fall tires. Period. In British Columbia, where they know something about snow, you're strongly encouraged to have actual snow tires in the winter. Sometimes the RCMP sits at the bottom of the Whitewater access road and checks tires. You get to pay extra if your tires are deemed inadequate.
And to 4ster, who said:
Find & empty parking lot...
I have to say, yes, by all means. If you're planning to spin some doughnuts in a parking lot, by all means, empty it first!