Dream about tornadoes and being separated?

I had a dream that i was at my middle school,( i am currently in high school) and the room that my class was located in was my grandmothers house. there was a large Tornado coming that we could see, but i ran as fast home as i could because i only lived a few blocks away. no one was home and i ended up back at the school/grandmothers house. when everyone went downstairs there was this greenish looking sick old lady and a really sick looking cat and everyone started screaming because the old lady was trying to attack them. we all ran upstairs.i then left in search for my parents(who are separated) i try both of their phones but no answer. so when i leave to go and find them i head to where they work. but when i get some ways away from the school the city turns HUGE almost Las vegas looking but the city never ends. so i find a shuttle train which i have never been in or seen, the shuttle is almost like a roller coaster but it takes me down to this water front. at the water front everyone is watching a tv and crying. on the news its talking about large volcanoes erupting in europe and it is going to make europe go almost complete under water(i live in america). it also showed videos on the news of the large cities being sunk down by the volcanoes. I run away as fast as i can, i end up in these trails that go through a forest that is located in my town that i go to very rarely and there is this coach (the wagon and horses) and he tells me to climb in and he is very nice. and then we end up Driving into the forest a ways with a few other people and the dream ends. and i never did find my parents. what could this dream mean or indicate?