I am going to get out of the house this weekend and fish the MF Snoqualmie. My question is, knowing that it will be high due to rain, knowing that visability will be poor/good, what patterns would you suggest.
Toss anything that floats and is a reasonable sized immitation to whatever you might see in the air. I know, sounds generally unhelpful - but as you've undoubtedly seen in some other threads, there have been fish of all sizes cause on something as simple as a royal wuff. So, for the sake of maintenance I would pick something that'd hold the floatant well for probing. Just concentrate on a drag free drift. If you you see any big fish that are getting shy, then switch it up to a smaller sparse fly.
If nothing is happening on the surface, then give a red or amber copper john a shot. I've always had decent luck on those in the Sno systems. Otherwise - do my favorite activity and start some seining to get an idea of what sized nymphs you ought to be chucking.
I would recommend tying on a big dry fly. Bigger than you think you should. Its a bit counter intuitive because most of the fish are 6-9 inches, But a #8 stimulator or a #10 orange humpy will draw the interest of the biggest fish in any given hole and the really small fish will not be able to get the big bushy fly in their mouth. These "high graidient" trout are ravenously hungry right now.You could, of course, drop a small nymph or soft hackle off the back as an insurance policy.
I've heard that a large dark stonefly nymph works very well on the Snoforks, but I have not proven that technique myself yet.