The NPS is reporting that highway 123, currently closed at mile post 0.4 from the highway 12 intersection just before the Summit Creek Bridge, has 11 trees (12" to 30" diameter) over the highway along the length of it to the NP boundary and in the NP. The highway currently has over 12" at the intersection with highway 12 to the NP entrance and over 36" at the Ohanapecosh Ranger Station.
This means that the highway won't open in the spring for sometime, until the seasonal snowmelt allows clearing the highway, the trees can be removed and the road can be checked to Cayuse Pass with highway 410 for avalanches and landslides and for any winter damage. This mean sometime mid-to-late April at the earliest and probably May.
You can get the latest information for the access and conditions in Mt. Rainier NP and at the Washington Department of Transportation Websites for Mountain Passes.