Whenever you inevitably port Weather 2 to 1.21, I have a few changes and additions that you can use to make the mod better.

1). Damage Improvements
Please have a look at #667 for a detailed explanation of this. TL:DR, the tornadoes should pick up more depending on the tornado's intensity. Right now, tornadoes are very weak.

2). Reintroduction to Wedge Tornadoes
What I liked about Weather 2 for 1.12 was how big the tornadoes could get. I think this feature could be re-introduced, but in a different way. In real life, wedge tornadoes form when warm, unstable air collides with cold, stable air. To recreate this, maybe tornadoes that form in biomes that border cooler biomes have a higher chance of growing into a wedge tornado. Since the size of a tornado has nothing to do with its strength, EF1's could become wedges if the environment was perfect enough. Wedges aren't locked to a certain tornado intensity.

3). Tornado Speed Adjustment
I think the speeds of all the tornado types should be randomized. Sometimes, an EF3 can move slowly, other times it can move at a faster speed.

These are just some basic suggestions, I'm really loving the mod!