A map that has weather particles PMIed into it.
First, open HHT and scroll to [sbsp] Structure BSP.
Now, open it. A name will pop up being "levels\test\-nameofmap-\-nameofmap-"
Click it.
It will take a little bit of time to load all of the things, and it might seem like it isnt doing anything. It will gradually add things to the list. Once it is done (you will know because all the things under "Tag Viewer" will be highlighted with a tan-ish color while it is loading) then scroll all the way down to the bottom. one of the dependencies will say "rain- Nulled Out".
click it and swap it to whatever weather particle you have PMIed into the map.
Done!
Pic:
