[BTS] Creating a semi-permanent effect

Hello!

For my mod I want to include storms. I have already set up the code to create storms and to manage their effects, but I need to know how to keep the visual effect of the storm going through the duration.

I am currently using the tsunami effect from gods of old (the clouds one not the coast one) and calling it with:

but this code only spawns the effect for as long as the effect lasts... I need it to last until the storm ends (which could be in several turns).

Any ideas?

Thanks,
Jamie