Depending on types of precipitation, snow conditions, altitude, activity considered, temps and wind velocities, usually use one or a combination of these:
32 Deg. brand base layers.
Merino base layers.
Light to mid-light fleece.
MH Mountain Bibs, Tru-Spec H2O ECWCS pants or MH Returnia Pants as shells.
The bibs and ECWCS easily accomodate Marmot Tarn or Scree pants with mid layers and/or tactical clothing with mid layers.