Here's the thing with those apps, include the one included on the iphone - even if there is chance of snow or rain at 1am in the morning, the day will show snow or rain. So many partly cloudy fine days will happen the majority.
No knowledge of the algoritm used but certainly check the hourly the day before.
Unless you are hiking in the high peaks. If a report says only 10% chance of rain in a day, that mean 100% in the high peaks. Always. May not be heavy, but it will occur.
I'm keeping the Seattle tickets. The PNW has had the most stable snowfall forecast over the past few days, whereas Tahoe has been all over the place. Utah and the Front Range now may both get snow Thursday into Friday, but no confidence (could be significant, or not) in amounts. Not super terribly confident about the PNW amounts, but I've got 3 different forecast sites all in agreement on the weather pattern, and 1.5 to 2.0 inches of QPF through Sat with all snow on the upper elevations should (hopefully) put into play the upper mountain stuff I want to ski.
Don't need storm day skiing or untracked powder, so the weekend forecast doesn't concern me as much as the forecast leading up to the weekend. You are right, neither has anything eventful over the weekend, but the PNW looks more active through the rest of the week. We'll see....