I noticed on my last trip to NYC, that alot people carry umbrella in their bags as do I. And I got to thinking that a bag could have an umbrella pocket on the outside of the bag with some sort of drainage so that when you close it wet, it can dry out alittle. Nothing is worst then putting a wet umbrella in the bag where other things could get wet. Also, have the pocket waterproofed on the inside so that moisture doesn't seep into the rest of the bag.
Just an idea...
We try to make our water bottle pockets do double-duty and also function as umbrella pockets: mesh drains water well either way.
We live in a rainy place too (Washington's Olympic Peninsula), so umbrella storage is a consideration.
Thanks for you input.