Raymond Zhong and Erin Schaff

Sensors on low-flying planes can measure mountaintop snow with great precision, helping forecasters predict what will happen as it melts.

Ever since an eruption in Hawaii halted a long-running record of carbon dioxide, scientists have found ways to carry on — atop a neighboring volcano.

A Times reporter and photographer rode along with a team gathering data on the colossal atmospheric rivers that have drenched the state.