Below is an email I sent to a western states LEO that was asking about layering for cold weather. Feel free to use it as a primer to answer your initial questions and then let me know if you have specific questions to be answered.
here are some things to consider regarding layering and where you work. you are definitely in a challenging area. the land of many mountains, high desert and high winds can make for a challenging way to manage your body heat while working with tacti-cool gear. the critical issue is to maintain a balance of body core temperature and also minimize perspiration which will accelerate dehydration and also can be an issue with evaporative cooling when you don’t want it to happen.
here is what i use, some of it is commercial mountaineering gear and some is military gear. i mix and match because i don’t alway wanna loo like a barrel chested freedom fighter (Kilimanjaro, Africa) and frankly i like lightweight gear for my wilderness operations. it allows me to move faster. as long as the colors are muted, such as drabs, khakis, grays, etc i will use it.
i made a switch away from polypro and capilene about ten years ago. i have favored merino wool due to its lightweight, non-funk smell and it works in hot and cold weather. i have a variety of merino thin bottoms from Patagonia, smartwool, helley Hansen and the like. i prefer thin layers of wool next to my skin because my legs heat up when i am hiking. i have had nights on bivouacs where my legs are still kicking out BTU’s from a rugged climb and i didn’t need thick expedition weight bottoms for them.
on my torso i always wear a merino wool t-shirt. i get the thin layered ones form anywhere i can get. Golite makes nice one and you can find subdued colors form Patagonia. over that i like to wear a thin merino long-sleeve hoody. I/O makes one that is black. it has long sleeves with the thumb holes for improvising extra hand/palm warmth. the hoody i like because at times if i am out hiking in windy conditions the hoody is thin enough to not block sound, but enough thickness to slow down wind drafting down my neck. this is my base.
now when i go mobile in the hills i like to start out with thin layers and be a bit cold. i will heat up quickly and i don’t want to perspire. that is the worst thing that can happen on a long search or potential overnight bivi. the sweat increases your risk of cold exposure and frost injuries. now think of slapping a plate carrier on your torso that has no permeable material to allow heat and moisture to escape and you can start seeing a problem creating. so i typically use a lightweight wind/water resistant shell top and bottom. normally this is the soft-shell or schoeller type material. i prefer a pant that does not have a heavy material with all the side pockets and reinforcements that you see in a lot of the tactical pants. as long as the pockets can be zipped shut so i don’t loose things and the accommodate a 1.5 inch belt i am good. one of my favorite is a pant from beyond tactical.com
that i had made. very light yet durable. for the top i like full zip hoodies. hoodies rock especially when wearing a brain bucket. (normally on a wilderness search i don’t wear the helmet unless the NODs are attached and i am working at night) just me. Marmot and Outdoor Research make awesome hooded SS jackets in muted colors. i slip the PC over that gear and i get moving.
so now comes the issue of cold or wet conditions. you don’t want to get wet because the operation will become a major suffer fest. you don’t want to get cold because you can loose cognitive thinking, tactile feeling and even digits. first lets cover wet.
most people wear gore-tex or rain gear clothing at the wrong times, thinking it will keep them warm. think of to this way, gore-tex and rain gear are just giant ziplock bags. they trap moisture on the inside and repel moisture on the outside. some claim they are permeable, but in reality most people sweat inside of them. also waterproof breathable are not an insulating layer to keep you warm. but they will work in sealing or preventing your hot body temperature from escaping into the ambient air and prevent you from evaporative cooling process. so most of the time my WPB top and bottom sit in my backpack. probably 85% of the time. so i view my WPB gear in this light. if i am rarely wearing it, but i need it, want it to be damn light weight cause it will be weighing me down in my backpack. Patagonia and Arcteryx are the kings of lightweight WPB shells that i use.
now cold is getting to your question regarding the Arcteryx Atom SV hoody and the Patagonia Level 3 Alpha Jacket. I own and have used the Atom, sorry can’t speak directly on the Alpha Jacket. here is the critical thing. loft jackets are most efficient when being used in a sedentary activity, such as bivouacking or holding post and not moving your body to create heat. i never hike or climb while wearing a loft jacket. just to damn hot. so when i am sedentary and setting up an observation post i want the MAX ability to trap and retain my body heat. this is where goose down is the cats meow. the more loft or FILL rating the better you will be. the reason that down is better for this is again its weight ratio. the thing will be sitting in my pack adding weight while i am moving. down is much lighter than primaloft, synthetics, etc. i prefer a down jacket with at least 850 FILL for maximum warmth. GoLite and Patagonia make excellent jackets. this year North Face, Golite and Patagonia have released a hydrophilic down that retains its loft even when wet. traditionally down is about as effective a gauze for contraception when it gets wet. hell it turns to useless oatmeal in your jacket when wet. i had a down jacket get soaked after mom nature hurled plunging fire hail and rain at me on a climb up the Grand Teton. i was lucky that i was at a windy mountain pass and was able to stake out my jacket in the wind for 30 minutes and the wind dried out the down so i could press on. the new hydrophilic jackets are also supposed to have a more waterproof nylon cover to prevent the down from soaking. i just store my down jacket in a trash compactor bag (damn tough) and leave it in the bottom of the backpack. so i guess an answer to the Alpha and the Atom is that you will have to carry more weight and have less warmth ratio than if you had down.
i had to teach a carbine class in Moab, UT just before christmas 2013 when that crazy cold arctic air rolled in. we trained in -2 to 12 degree weather for two days. i wore smart wool thin bottoms, soft-shell Golite pants, patagonia wool T-shirt, I/O merino wool hoody, Marmot dry-clime hooded wind shirt, Outdoor Research hooded soft shell jacket, Outdoor research gripper gloves and an arcteryx wool beanie. I was not wearing my plate carrier, which would have increased my warmth, but i did have a Patagonia micro puff vest that i wore in the early morning and then shed it off cause i was getting warm. i never used my down coat during the two days.
i would be happy to go over footwear, socks, hand wear, pack loads, etc at a later time if you are interested.
if you are not a member of promotive.com
they give LEO discounts on some of the above equipment.
outdoor research, arcteryx and Golite have pro deals to LEOs also.
next time you are in Reno. Patagonia and Sierra trading POST have outlets with some good prices for gear and clothing.
hope this helps