I had a similar experiance in narragansett bay a few years ago. Sailing nicely wing on wing up the east passage when I heard a low rumble. Step one, pole down, sail a reach, assess weather, Blue skys as far as I could see (I couldn't see the other side of the island). Seconds later, louder rumble, step two, roll the jib, start the engine and strike the main. By now I reached the tip of the island to OMG black skys.
Running to Wickford was a breif option but the sky closed that path. No sooner did we get the boat closed up and PDF's on did it hit. Blinding rain as in I couldn't see the bow of my 28' boat. Waves and wind like I've never seen in this part of the bay. I ran with the wind noting my positon and compass heading. This lasted for about 5 minutes then dead calm. I turned the boat back to my heading and a minute later the other wall hit. Now I was heading south same wind and waves. 5 minutes later dead calm again. This time it was through. Later that night the news reported 75 mph winds at the Providence airport. Yes it was time for a new pair of shorts.