The Sierra Nevada snowpack remains almost 30 percent below average for this time of year despite a boost from the weekend storm, state water officials reported Tuesday, as agencies begin snow surveys by hand throughout the mountain range. Electronic measurements show the snowpack’s statewide water content at 10.5 inches, which is 72 percent of normal for Tuesday. Staff at the California Department of Water Resources and other state, federal or private agencies will snowshoe or walk to about 20 key monitoring stations throughout the Sierra over a 10-day period starting this week for the first manual snow survey of the 2016-17 winter.