Sierra snow pack normally gets deeper and deeper until around March 20-25. After that date, sometimes a little more snow falls, but it is offset by lots of melt. So after that date, the snow depth begins to diminish. Snow depth is the first thing that snow surveyors measure.
The second thing is water content. The snow does not contain a constant amount of water. It might be powder, or it might be slush. The surveyors measure the water content, because for Water Resources purposes, that is what counts for water quantities.
Yes, once in a while we have a cool spring. The snow still melts, but it melts very slowly, and it can cause huge snow drifts to persist through summer. A cool spring is hard to predict in advance.
So, lots of Californina backpackers are watching the snow reports and are trying to figure out the right time to plan for. For a trip around August 1, I have jumped to the conclusion that conditions will be within one week of normal for August 1.
Meanwhile, my skier friends have ducked off to Whistler.