Instead of using generative AI, I would probably make what appears to be rain. Here's how:
- Make a new layer.
- Make sure the foreground and background colors are set to the default black and white (click the small black and white icon above the colors in the toolbar).
- Go to Filter > Render > Fibers... and set bump up the Variance and Strength as needed to get some good contrast.
- Rotate the vertical fibers 90° so that they are horizontal.
- Go to Filter > Stylize > Wind... and set the Method to Blast.
- Rotate the layer -90° so that it's vertical again.
- Invert the layer so that it's mostly black (Image > Adjustments > Invert).
- Set the blend mode for the layer to Lighten or Screen.
- Reduce the opacity of the layer.
- Skew and scale if you'd like the rain to appear to slant.