Mitzi is afraid of any strange / loud sounds. It didn't help that a couple of years ago the neighbors catty-corner to us set off firecrackers all day/night long, a couple of times when I had just taken her outside to pee. - IMMEDIATE return to the house, practially dragging me. -
We live within sound of the main roadway thru our area, and *any* strange noise from cars/trucks/motorcycles/emergency vehicles / construction / you-name-it, and she's pulling for the house.
The thunderstorm issue is bad enough that she starts pacing or trying to hide up to 15 minutes before we start to hear anything, and sometimes it doesn't even have to be thunder and lightning. - Even a good, heavy downpour will trigger her anxiety. With observing that she's either trying to dig her way to China thru my bathtub, or trying to fit herself into a space where there's no way she'll fit, we've decided that the best place for her to feel most comfortable is in her kennel, with the cover on. - It's enclosed, dark and away from most all of the noise.
This also goes as far as her not liking the flash from a camera - we don't know if her being the main picture-subject from 4 people with digital cameras in the same household made her not like lightning, or if lightning made her not like the camera flash....