With every storm this winter, climatologists and water managers have crossed their fingers, hoping for continued rain and snowfall to cushion the state’s water supply. So far, the streak has held. This week is expected to bring the heaviest rainfall of the season to date, adding to an already wet winter that has replenished reservoirs and created a healthy snowpack in the Sierra Nevada, a major source of California’s water supply. Climatologist Michael Anderson said that after hovering just below average precipitation levels, the state has now reached above-usual levels — with an average of 11.85 inches of precipitation across the state from October through January.