They are done with the rock blasting on Snoqualmie Pass until after the holiday weekend. But it is very likely that you'll get stuck in traffic heading over the pass. If you've got cooling issues with the truck and slow traffic is a no-no then I'd definitely recommend leaving early in the AM. As for Blewett Pass, be prepared to slow down below 45 mph. As others have indicated, it's easy to get stuck behind slower traffic on that roadway. The good news is that there are occasional turnouts and places to pull off the road so if you have an issue hopefully you can find a place to let it cool off. You might want to have the fan clutch on your truck inspected as it is a likely culprit for the condition you describe. Good luck.