Hello James and welcome to the Orchid Board.
Catasitenae orchids (the family including Monnierara) are deciduous plants and it is totally normal for them to loose their leaves every fall. At this point you should reduce watering, or maybe even stop it totally for the winter if you live close to Seattle. For comparison, I live in southern California and I will totally stop watering around mid-December.
You should only resume watering in the spring when the plant has a well established new pseudobulb with roots many inches long and new leaves. After you resume watering, you should keep the plant much wetter than other orchids. In the middle of the growing season, I often totally waterlog the sphagnum moss where my plants are, and it is already almost dry the next day. Catasitenae also need a lot of light. I keep mine is a south west facing window where they get about 8 hours of direct sunlight every day in the summer.
While waiting for the spring, I encourage you to browse through the Catasetum forum on Orchid Board, to look at the website of Sunset Valley Orchids (
Sunset Valley Orchids - Superior Hybrids for Orchid Enthusiasts), and to look for videos on YouTube describing Catasetum culture. One channel with a lot of useful information is that of Steven Van Campen-Lewis (also known as isirus79 on Orchid Board). I find his PET potting method impractical for indoor plants, but I still learned a lot for his videos.