Crazy shedding and dander?

So Sonic was 10 when we adopted her in May. She's huge and SUPER fluffy with soft fur that never mats up. Her winter coat has started coming in like crazy! She's been looking extra poofy. While there has been a TON more shedding today I noticed some dander on her black fur. I don't know if this is something that happens every year since we've only had her since May; or even if it's something common for long haired cats like her since I've only owned short haired cats before her?

Long hair cats do tend to do that. Brush her often. It will help.

Thank you!