But...the entire mood was light and fun.
Storm is even laughing and enjoying the camaraderie and touching moments. Apart from the possible underlying sadness of leaving (and Storm by that time was fully committed in her decision to do so) there really is nothing to indicate her being so violently and emotionally affected as to inadvertently create such a tempest.
And...if it was a storm of her making, inadvertently...she would have quelled it when Emma made her comment. She didn't.