I'm pretty sure flat top is open. I was there last weekend & it was an easy drive.
I was up on Mt Adams yesterday & there were a bunch of folks heading to flat top.
Try riding on actual Mt Adams (above the tree line) if you havent already. It was beautiful yesterday. Calm, warm & sunny, with clear view of hood. The snow up there is wind packed so it's generally smooth.
Also try Mt St Helens. 1.5-2hr drive from Portland.