An unseasonably cold Arctic airmass sits over the BC interior. The leading edge of the Arctic air lies along the outer coast. An upper trough moving southwest will induce a surface low off northern Vancouver Island.
The low will bring overrunning moisture to the Arctic air on the South Coast later today. Precipitation should be light tonight through Sunday morning because the layer of moisture likely won’t be deep enough to produce heavy snow. Light snow will spread into the Southern Interior tonight.
The pattern changes Sunday afternoon when more Pacific moisture joins into the Arctic air stream, developing moderate precipitation over southern areas. The Central and Northern Interior will remain dry and cold with strong outflow winds
persisting through the mainland inlets and valleys. The pattern doesn’t change much on Monday except freezing levels will rise on the on the South Coast.
The models are fairly similar with the pattern and with the northern extent of the heavier precipitation Sunday and Monday. However, the Canadian model (especially the 06Z run) shows somewhat higher QPF for tonight and Sunday compared to the ensemble average and to the foreign models. With the cloud tops barely into
the snow growth region tonight and Sunday morning there’s much uncertainty around how much snow will result.