I live in Baker City which is along your route and sometimes drive to the Seattle area to visit my sister. The bad news is that it can get very slippery on I-84, as you can see here:
http://www.bakercityherald.com/news/...?story_no=5711
The good news is that the weather should be much better on Saturday. About a 40% chance of snow showers, which isn't too bad. Right now the road is clear.
Before you leave, check the link the previous poster provided.
Also, check Washington information for the troublesome pass here:
http://wsdot.wa.gov/traffic/passes/snoqualmie/
If the weather isn't bad in Washington, don't bother to go to Portland, especially if the conditions are bad in the Columbia river gorge.
If I remember, I'll post updated information tomorrow afternoon.