I've crossed over the Five Finger Ridge and stepped out into the cirque at the top of the mountain. I'm now well above the icefall. That's Middle Peak to the left and you notice that there isn't much of a slope. We're in the summit bowl (alpine ski resort speak) and this is where Mt. Olympus catches all the snow it takes to generate the Blue Glacier.
Annual precipitation equals 220 inches here. That's a rainfall equivalency. Almost all precip here falls as snow. It's usually wet coastal snow, not fluffy, dry, Utah-style snow, so figure conservatively that 6 inches of snow reduces to an inch of precip. That's 110 feet of snow a year on average.
Again, speaking as a Texan, isn't this beautiful!