For me good winter gear includes extra food, clothing, gloves, tent for the environment, sleeping bag and snow shovel, and extra gloves. And gloves . Yes, that's my dayhike kit. I wouldn't plan on digging a snow shelter or erecting an igloo, that's a lot of work without alot of free Scout labor, I'd rather look for a tree well, dig that out, and pitch a tent for the night. You can't throw a rock and not find a tree well in the PNW, short of that I'd rather hunker down my tent in a semi-recessed snow bank and build up snow around it to keep the wind to a minimum. Digging a shelter expends alot of energy you might need later, and makes you sweat buckets, possibly compromising your body warmth. Carry adequate shelter and supplies, and concentrate on staying warm, dry, and getting out of the cold, hydrating, and heating up dinner. Then wake up, and walk out.