Yep, we're going to tell you how to build a Jeep for the snow at the beginning of summer. That way, you can get a jump on all the things you'll need to do for a safe and enjoyable wheeling experience in the white stuff. Failing that, you'll be digging through the bathroom magazine stack trying to find this issue by the end of the year.
Before you head out, check your Jeep really well, grease anything that holds it, check the condition of U-joints, and make sure all your fluids are relatively clean and free of water. If you've got a winch, verify that it's in working condition. It's much easier to check this stuff at home than it is to fix it after your Jeep has blown up on the trail, leaving you stranded in 2 feet of snow.
Engine: The deeper the snow, the bigger the tires get and the more power will be needed to get through it. The more power the engine produces, the bigger and beefier the components must be to use downstream. It is a vicious, never-ending cycle. Try to stay out of it if you can--sure, more power helps in the snow, but unless you are conquering 4-foot drifts, anything less than axle depth doesn't require 1,000 hp.
Cooling is one area many people forget about. While it is true that it'll be cold if there is snow on the ground, powering through all that white stuff puts a huge strain on the engine, and when the engine works harder, it gets hotter. Make sure you've got a fan shroud if you're running a mechanical fan. Also, make sure that you've got a 50/50 mix of antifreeze and water in your radiator. You can add more antifreeze for much colder climates (for example, climates that never get above freezing), but 50/50 is good for most of us.
Make sure your exhaust is in good shape with no leaks. We don't need to tell you that carbon monoxide poisoning is bad.
Transmission: If you've got an automatic, cooling is key here, too. If you don't have a cooler, add one. Also, a deep pan and a higher stall aftermarket torque converter can help out here. There will be a lot of rocking back and forth to work out of being stuck, and the transmission will get a nice workout.
If you've got a manual transmission, make sure your clutch is in good shape or add a Centerforce dual-friction clutch or something similar. They stand up well to the feathering of the clutch that is needed to rock a manual Jeep out of the snow.
Transfer case: Unless you're running a really anemic four-cylinder, forget about the Low range add-on for the transfer case; run the stock Low range if you need it, or just leave it in High range. The goal here is to spin the tires while maintaining forward momentum. It's hard to build any momentum with a 300:1 crawl ratio.
Axles: If you've fallen into the bigger-better-more-power game with the engine, you'll need bigger axles to handle that power. Fancy whiz-bang axleshafts and hoo-ya joints aren't really needed here, though. It's not like you are going to be wedging a tire into a crevice and then applying power through myriad gear-reduction units. If, on the other hand, you are rockcrawling in the snow, all the rockcrawling hints elsewhere in this issue apply.
Interior: Bring an emergency blanket and make sure you've got a CB, Ham radio, and/or a cell phone to call out in case of trouble. Old Man Winter is not a cozy bedfellow for the unprepared. Plenty of water, food, and cold-weather supplies are good ideas to carry along inside your Jeep.
Tires: The type of snow and how many horses are under the hood will be the determining factor for tires. If the snow is not as deep as the axles, mud tires or aggressive all-terrains will work. If it's up to your axles and you don't have a really healthy engine, stick with less aggressive mud terrains to keep on top of the snow. If you've gone into the big engine and axle cycle, run Super Swamper Boggers or something similar for the paddle-like design. Unfortunately, these aggressive mud tires will suck on ice.
Suspension: While we normally preach low and stable, if you are off in the backwoods plowing trails with your front bumper, you're bound to get stuck. Here, a lift to clear whatever tires you run without cutting fenders is going to be your friend. Once the snow gets to your front bumper, you're stuck, so a goofy-tall Jeep isn't a bad thing.