I think she was so overwhelmed by all the snow bullshit that she actually thought a blizzard was going to find its way inside the Transbay Tube and into an airtight BART car, and get her a little wet.
Or maybe she just really hates when the person in the seat in front of her sneezes and doesn’t cover their mouth.
Or maybe she was practicing some kind of understated routine for the Glee tryouts.
Maybe her umbrella was broken and wouldn’t fold up and for some reason she refused to throw it away and buy a new one?