I had a nightmare what could this mean?

Ok so i know dreams usually dont mean anything but i had a dream where my dad died ive had a couple before but nothing reallys happened for example one time i dremt we were in this like jungly area and he was across a wooden bridge and he was tied by ropes spread eagle i ran towards him trying to help him but i couldnt he just told me i love you and i woke up crieing i was like 9 well anyways (thats just one) this dream i waved bye to my dad got in a car and after he was out of sight i saw this huge mushroom cloud and he died it was on the news and etc i my mom was crying and so was my sister but i said in my dream i never got to say i love you were kinda close in a sense we dont have the best relationship but we have our moments what could this dream mean? im really worried i love my dad but i dont show it much i dont want him to die.