You could find yourself in 4 foot short period wave action coming from all directions. Picture a washing machine.
It's a lot easier to shake out a reef than to find yourself way over powered in the river and trying to set a reef while you are dealing with current, traffic and the bounce.
At the same time, you'll need enough drive to keep your boat speed up, those short period waves knock your speed down to nothing and you can lose steerage. Not a good thing when you're dodging ferry boats, and tugs pushing barges
I think this is a worthwhile subtopic for further discussion (maybe in a new thread?): maintaining forward progress on a beat against steep chop.
I was out a week ago into an unexpected norther (always drives up big waves for us on the southern shore of Lake Simcoe - ~15-20km fetch) running jib & jigger with the 100% working jib up. We took off beautifully close hauled as we came around the point into the wind, but then stopped cold when we hit the waves. In the end we turned back early finding the boat had a lee tendency (even with the mizzen sheeted all the way in) and the helm little help since we were making very little headway. Tricky at best from getting pushed to beam-on.
I have been out in similar conditions with a smaller (70%?) storm jib and found I could keep the course I wanted with some work (head up into big ones, fall off and make a little headway when you have a lull) and make SLOOOWW progress. Helm response very limited, but can manage by changing mizzen trim. I wouldn't have wanted to do that if there was any traffic I had to dodge.
Of course turn and run at ~135 degrees off and she hauls tail and handles the rollers passing underneath, no problem. But that will put you back up on the lee shore real quick...
Anyone have experience dealing with these conditions? Maybe a fin keel and modern hullform would do better :-) or fire up the iron genny.