This is how I colored the snow falling and the wind on my most recent coloring of Loki from the One Piece chapter 1130.
Normally, the easy way would be to just fill in the original line art. However, given I wanted to add a motion blur effect, it would make more sense to have a new layer above the line art to give it that realistic almost three-dimensional effect instead. Remaining within the original line art makes it look flat. So with a normal, bold brush, create the same shape of the original snow above the line art (I made it the uppermost layer, to avoid being behind the highlights I added on the characters).
Once you create all of your snow circles (which can seem a bit tedious work, but it’s definitely worth it), you can alpha lock or clip mask to add a little bit of a shadow using a second color. I used a bright teal color. You don’t have to be too precise with the shading, since we are going to blur these anyway to save you the extra work of adding a perfect shade on each circle.
Now, you can duplicate your layer and change the color to a deeper blue, which you will then blur with Gaussian Blur on the whole layer (make sure this layer is underneath the original snow layer). This will create a soft glow underneath, with the Blending Mode Screen. I was debating whether to leave the snow with the Blending Mode Add to give it some more brightness, but the shading was lost, so what I did instead is I duplicated the snow again and applied the BM Add and lowered the opacity just to give it a slight brightness.
I love using Chromatic Aberration to create an extra outline but not too harsh, followed by the Motion Blur effect to make it seem like the snow is fiercely falling with the wind.
Finally, we can follow the trace of the wind drawn in the original panel (if provided on the line art) and create the wind pattern. If there is no line art for the wind, then feel free to create it on your own if you want to add that extra effect on your colorings. I used again the Blending Mode Add but with lower opacity so it doesn’t look too harsh, and cleaned it up a bit by erasing the ends so it doesn’t look like just a plain line. Bonus tip, you can erase the original wind line art so it looks smoother, and re-draw the line art that should be underneath the wind. In this case, I completed some of the chains and Loki’s hair.
And there you go! Now the panel was significantly enhanced by these special effects, making it look more intense and epic, perfect for a major character reveal!
Hope you found this tutorial helpful, let me know in the comments if you have any questions! :)