[81alum]

Re the highlighted statement above, don’t bet on that. If the rest of the season is dry and sunny, sublimation will occur. That means no runoff.

The studies I have been looking over estimate sublimation at around 15% of snowpack, at most.  The southern Sierra is already at 123% of April 1 normal, so I think we are on track for at least a normal year in much of the Sierra.  However, I'd like to see the whole Sierra get well above normal before rejoicing.  And we really need to do a lot better than normal to make a dent in the drought.  We need more snow in February and March.

A bigger worry, perhaps, is that a too-early melt could occur, as with a rain-on-snow event, which would release the water in the snowpack too early before it could be stored or used.  Many reservoirs can't be filled early since they need to reserve space to prevent potential flooding, so ideally we need the snowpack to stay cold and in place until flood danger is over and irrigation season needs it. 

Warmer winter and spring storms could produce this kind of disaster, and they are probably more likely in this era of changed climate.  It was a warm rain event that produced the flooding of 96-97, when rain fell up to 10,000 feet in the Sierra on New Year's Day.

[81alum]

Re the highlighted statement above, don’t bet on that. If the rest of the season is dry and sunny, sublimation will occur. That means no runoff.

The studies I have been looking over estimate sublimation at around 15% of snowpack, at most.  The southern Sierra is already at 123% of April 1 normal, so I think we are on track for at least a normal year in much of the Sierra.  However, I'd like to see the whole Sierra get well above normal before rejoicing.  And we really need to do a lot better than normal to make a dent in the drought.  We need more snow in February and March.

A bigger worry, perhaps, is that a too-early melt could occur, as with a rain-on-snow event, which would release the water in the snowpack too early before it could be stored or used.  Many reservoirs can't be filled early since they need to reserve space to prevent potential flooding, so ideally we need the snowpack to stay cold and in place until flood danger is over and irrigation season needs it. 

Warmer winter and spring storms could produce this kind of disaster, and they are probably more likely in this era of changed climate.  It was a warm rain event that produced the flooding of 96-97, when rain fell up to 10,000 feet in the Sierra on New Year's Day.