When packing for quick back-to-back trips to two different locales, it's useful to pack two separate roll-aboards. For our current itinerary we packed a Quebec bag with warm clothes and a Hong Kong bag with warm weather garb. We have one bag with us, and the other is sitting in our car awaiting our overnight in Seattle. This kind of organizing really pays off.
Incidentally, before departing, make sure you've taken the correct bag out of the car. The good news is that it's a lot warmer in Quebec City than we thought it would be (even with a few lonely piles of snow still visible) so our Hong Kong clothes should work fairly well here. The next challenge will be repacking for the Hong Kong trip during our overnight in Seattle.