I've got a Illuminite Commuter jacket would work for you if they still made it. It's a heavy duty windbreaker with pitzips that has kept me warm and dry in a 40 degree downpour. There's room to layer under it, and it's too warm for me most of the time, especially in the arms. My arms usually sweat when I wear it, but something like that might work for your 15 minute leisurely commute.