im trying to get into cold weather backpacking (northern MN all times during the winter) where temps could range from 35 to -20.

im want to put together a few light jackets to make a go to jacket for these situations. such as the 3-in-1 jackets that are common at say rei. i already have a light weight down jacket some may call a sweater.

what do you guys use as the outer shell and do i need another layer (this is not including my long underwear and shirts)

I don't try to use one shell for the temperature range you are talking about.

near freezing, I will use a waterproof breathable or nylon I use a very thin unlined lightweight WB shell near freezing, underneath that goes a base and insulating layer. Waterproof breathables work ok when there's a moisture differential, and it's not deeply cold - so that the water going through them is still vapor.

Once I get down to consistantly below freezing, I.E. I am not going to get rained or drizzled on, I actually use cotton. A cotton denim type anorak that cuts the wind, will frost over, and will breathe like mad in freezing temps. Underneath I will have layers of down sweater and/or wool. and/or fleece. the job of the shell then is to breathe (so my persperation can get out) but cut the wind, and deflect the snow as I go through the brush. it's *not* meant to be waterproof, as I want it to do it's job even when it itself is below freezing. I have two anoraks like this I use, and white cotton one I picked up cheap at cabelas. They need not be expensive, just loose fitting (to go over your other stuff) and a nice hood on them to keep snow from the bush from coming down your neck.

That's what I use for moving around (i.e. hiking/snowshowing) in winter winter. I usually in my pack then have a big poofy 700 fill MEC down parka, but that's for sitting still - I don't wear such a thing when I"m active because it's a moisture trap.

I am pretty similar to phat. I have two shells. One is a gortex one that has no insulation. I use it when it is wet, hovering around freezing. When it gets below 20F I switch to a cotton anorak. I bought a cheap Swedish one at a surplus store. It breathes and cuts the wind. Then, underneath, I have a bunch of fleece like jackets that don't cut the wind. Some are wool and cut the wind pretty good, some are polyester fleece and don't cut the wind. Depending on the trip and how heavy I want to be determines if I take the wool or Polyester.

Cold weather is different for all of us. phat gets much more cold than we do down here.

My winter clothing system (for camping) is not jacket based but rather "uniform insulation everywhere" based. I ski with my pack wearing long underwear, a 200 fleece jacket under a paclite parka and paclite zippered pants. When I get to camp I have a goretex shelled expedition parka weighing 40 ounces and a pair of goose down goretex shelled bibs that weighs 32 ounces. Add warm gloves and a hat and its 5 pounds of clothes that I can sit around in at -5 F. Obviously this gear also extends the range of my sleeping bag system. BTW I take the bibs off and put them inside the sleeping bag to keep them warm, and the down coat goes over my torso over the sleeping bag. I wear the large paclite pants over the bibs to keep them dry so no moisture is carried into my sleeping bag.
Jim

Indeed. if You look at where jim is from, they're going to have less cold, and more moisture - likely wet snow. That's very different from an east side of the rockies deeply cold, a dry cold, with dry powdery snow.

There is a HUUUUGE difference between being out in wet snow versus cold dry snow.

Being in Minnesota (that's what MN is - right?) depending on where you are you're probably more of the dry snow and deep cold than the huge wet dumps. Heck you're only just south of
Winterpeg which is even colder than where I am