The season nine finale occurs as a superstorm rolls into Seattle, knocking out the power at the hospital right as Meredith goes into labor. Of course she requires a C-section, which must be performed in the dark, but thankfully, both mom and baby come through it OK. The storm also leads to a bus crash, which causes April to realise how strong her feelings for Jackson are when the bus explodes and she worries he has died. However, the biggest storm-related consequence occurs at the end of the episode, when Richard Webber gets electrocuted trying to fix the emergency generator so the lights can be restored.
In the season 10 premiere, which picks up still during the storm, Heather Brooks is electrocuted trying to save Dr. Webber. While it takes a long time for Richard to fully recuperate from his injuries, the damage to Heather's body is too severe, and she dies in the following episode.