A long or extended snow jacket drops past your hips toward your thighs, giving you extra coverage where shorter jackets leave gaps. This extra length really shines in deep powder—when you're carving through deep snow or taking a tumble, it keeps snow from sneaking up under your jacket. It's also a popular choice among snowboarders who spend time sitting in the snow to strap in.
The extended length is a game-changer on cold chairlift rides, since it covers your seat and thighs from the wind. Tall riders often prefer this length for the extra coverage and a more proportional fit.
The trade-off is that a longer jacket can slightly restrict your range of motion, especially when hiking or touring uphill. If you're doing a lot of skinning or backcountry travel, the extra fabric may feel cumbersome. But for resort riding in cold conditions or deep powder days, the coverage is hard to beat.