When it starts to look like this in Yosemite...

This is the view from Sentinel Dome above Yosemite Valley this week. Half Dome is always the landmark you want in the middle of these shots. Everybody knows what it looks like.

But not everybody understands how important it is to see the dome covered with snow. It's an indicator of the Sierra snowpack. If you don't see snow up there most of the winter, you've got a water problem.

And if you followed the webcam that takes these photos, you know we have a problem. Most of November, December and January, there was no snow up there. The snowpack stands at about a quarter of the April 1 average.

The state had a monster year last winter, so it's not a statewide emergency yet. The reservoirs are still fairly full. That's why people aren't making a scene about this yet. But they will worry next fall. A second dry year will make life very difficult for farmers, cities, industries and hydroelectric power producers.

One more time: Look out across the rooftop of California in the background of this photo. That's where your water comes from. More than half of the state's water supply melts slowly and thunders through these granite canyons down to 37 million people.