Your have pics with some good potential. Get a bigger camera...your Nikon 4300 is ok but at 4 megapixels you are missing some fun in larger files with less noise and raw possibilities. You should keep doing this, looks like you have an interest in danger under nice light, you're lucky to be able to witness this stuff.
I messed with two of them just to show what some simple stuff can do. These are all fairly easy things done in Photoshop. Playing with adding some color to the tornado shot, contrast for both, some cropping and burning and dodging. These files are small and noisy and start to degrade pretty quickly but you might get the idea that there is much more there than the files straight out of the camera will give you.
I'm not a fan of sunsets for the sake of sunsets, but I sure do like tornadoes and thunderstorms. I hope you don't mind, I cropped out the sun in your storm shot...we've seen that sun but we haven't seen that cloud before, ever. Personally speaking, it's the light I'm interested in, not the light source...
be careful man, those things will pick you up and leave you in places with no bus stops or liquor stores, bad combination.