The open end is facing East, the back wall is facing North. Both other walls are bordered by the other 3 rooms.You might want to invest in some greenhouse film if the temps go to where they were a couple years ago. Some black barrels 2/3 full of water on the north wall might also be a good addition. I'd also leave the southern exposure mostly open for airflow. Our weather seems to be very similar and I use greenhouses for their winter housing.

What are the black barrels of water for? I can cover the roof and both open sides in greenhouse plastic or (just thinking) putting a couple of the translucent roofing panels on top.
Normally, all my storms with a few exceptions hits us coming from the west or south west. I guess the mountains around here often determine how hard they hit.