Ohhhhh..... yeahhhhhh.
Heightened emotional responses, hyperfocus, and a VERY vivid imagination come part and parcel with ADHD.
AKA... I deal with these sorts of things with myself as an adult, and REALLY deal with them with my son (who is now 8).
At your daughter's age; it was "Other people following the rules", particularly driving, but any rule designed to keep people safe. The year prior (when he was first reading) it was genocide (people don't get that early readers read EVERYTHING).
Just last year it was the stupid rash of teen suicides being reported on the news.
Each one of these episodes it's taken less and less time to coax kiddo through them. I'm often reminded, both being and parenting ADHD, of a Winston Churchill quote;
"When you're going through hell... keep going!"
Neurotypical kids will often just "trust" in the god like powers of adults around them, or forget, or be distracted (and they say WE'RE distractible, hmph!). But with ADHD kids, when they latch onto a concept, it's often with bear trap intensity. The only way to 'fix' the problem, is to actually deal with it, on a daily basis, in great detail and compassion, head on. You just have to 'keep going'. They aren't going to believe "It's nice outside" or "Not everyone's a bully." They're going to focus on the possibilities, and those possibilities need to be thoroughly gone through to reach a point of emotional calm.
Last year's rash of suicides was the 'fastest' we were able to get through. Only 3 or 4 months a couple times a week. We had a really good foundation built from the driving thing, and the rules thing, and the other 'things' kiddo has latched onto. The first took 2 solid years to work through. Oy. BUT BUT BUT, not all at the same decible. The full on meltdowns, even from the beginning only lasted a few weeks. Then the meltdowns shifted into simple panic attacks. Then just anxiety. (That's the part that took about 2 years to soothe completely). Then (and now) just hyperawareness. I'm completely and totally convinced that my son is going to be either a cop or a journalist when he grows up. He is VERY hyperaware of what other people are doing, and whether it's "right" or not.
Part of what helped him enourmously during each of these episodes is actually just that; career exploration. Really digging in and learning about first the people whose job it is to deal with "x", and then (once he knows someone is on it, and reeeally understands what they do and how) he's able to release some of that 'responsibility' off of his own shoulders and look at the system that scares him.
Most ADHD'ers have VERY "and then what?" kinds of minds. When talking to us it can seem like we're skipping around from topic to topic, but they all tie in. What's probably happening is that your daughter has pieced together all she's seen on the news about the aftermath of storms, and is superimposing those same results onto people, places, pets she knows. When she looks outside, she isn't seeing 'outside' she's seeing a Sarah Connor Post Apocolyptic world where Mommy is dead, and her friends are dead, and her favorite climbing tree has been torn apart, and flooding, and, and, and.
What has helped with my son (and I do it to/for myself on a minute by minute basis) is making up stories. Okay. Let's say it's true (not the 'mommy dead' part, but lets say a storm comes. Slowly. Suddenly out of nowhere. With ice. With lightening. With food (cloudy with a chance of meatballs), any and every possibility THEY think of, or that might get a giggle). THEN WHAT do we do? Key point, the 'then whats' avoid the whole death of loved ones part. The 'then whats' include both the beginning, as well as the 'aftermath' like tree planting, and using flashlights, and all the rebuilding and how much fun that can be (aka positive spin!)... etc.
For my son, it is HUGELY relieving to him to a) be believed that something COULD happen, b) that a grownup has a plan, c) to be let in on/ help with what that plan would be.
Nowadays I can USUALLY catch these hyperfocus panic attacks at the very beginning of the cycle OR he does, all on his own (yay!!!). But the ones that get him THESE days, are the ones where the adults are scared. Where it's on the news with grim faced adults going for the 'drama', or worded in the papers in a "What can we do????" kind of way, and the TRIFECTA is when he's exposed to both AND the adults in his life are talking about it in a awed/angry/or scared kind of way. Hence the teen suicide thing became a SUPER big deal last year. (So got the trifecta, darnit! I swear WHEN will adults learn that kids are listening and reserve certain topics of conversation when they're around??? Sigh. Ah well. I suppose most kids just 'trust' that the adults have it in hand.)
Sorry this has been so scattered. I've only had 2 hours of sleep (heading back to bed now). I'll come back through and edit for clarity of thought, or at least bulletin points later this morning after I've had a nap.
R