Question submitted by James
Wow this sounds like such an easy question!
Basically Environment Canada issues a snowfall warning when a "regionally specific" snowfall amount is expected within a 24 hour period. The term "regionally specific" is crucial here. For example: for The North Coast - Inland Sections, the amount is 25 cm or greater, for the Coastal Sections - it is 10 cm or greater, and yet for the Greater Vancouver or Greater Victoria regions, the required snowfall is only 5 cm or greater. Rainfall warnings are similarly spatially specific - most coastal regions will get a rainfall warning when 50 mm or greater are expected to fall within 24 hours or less. For the interior of BC, the amounts are tapered down to 25 mm or less.
Now that being said, interior regions are broken down even further for snowfall amounts.
For a full description of all warning criteria breakdowns I would suggest you drop Environment Canada a note.