After a dismally dry February, drought-weary Californians are hoping a series of storms predicted to roll through in early March blanket the Sierra Nevada with a much-needed additional layer of snow, building up the state’s vital snowpack that all but disappeared last year.

Starting Friday, forecasters are predicting a chance of rain or snow for 10 consecutive days. How much water those storms might eventually supply to the state’s reservoirs depends partly on where they come from — warmer, wetter storms sweeping across the Pacific generally bring more snow to the mountains than colder, dryer tempests barreling down from the Gulf of Alaska.