Um, it's the Glen Boulder Trail. Not sure how far above it you went, but once you reach the ridgecrest you will be slammed, generally, with high winds. You will come across ice, the high winds I mentioned, steep slopes that fall into the Gulf of Slides...or, you could see sunny days in the 40's. There is no way to tell what you are going to have, but I would certainly plan on some ice and tough conditions getting above treeline.
You then have to walk about a mile straight into the winds, only to reach the Lakes of the Clouds HUT...which is closed in the winter. Not sure if you were planning on staying in it, but you might want to re-think the plan.
Not saying you can't summit Washington via Glen Boulder, but it's not a direct route and will add a couple of miles. You do avoid much of the steepness, but not all of it. It's not a route I personally would take, considering that you may not be totally familiar with the area.