A upper low over Alberta will keep the air mass over the BC interior cool & moist with a risk of thunderstorms in the forecast today. Most of BC is still void of weather systems thanks to the surface high over the Pacific, and temperatures will remain normal or just slightly above normal across the province today / tomorrow. However on Tuesday/Wednesday, the Southern half of BC will experience warmer weather with a upper ridge building in, while a default trough west of the ridge will move into the Northern Interior bringing the chance of showers midweek.
A weak upper level trough will track into the South Coast over this afternoon, bringing the chance of showers up through the Fraser and the Nicola Valley. Because the airmass over the Southwest BC is relatively dry, if showers do develop, some of the precip will likely evaporate before it hits the surface. Nonetheless, as we head into Tuesday, the showers for this region will decrease as a weak ridge builds in once again bringing dry and above seasonal temps for the Southern Interior. The ridge however doesn't have enough amplification to warm up the northern half of BC.