WeatherLetterExtensions - Vanilla-Expanded/VanillaExpandedFramework GitHub Wiki
This allows a weather to send a letter when starting. Add it to the <modExtensions> tag of your WeatherDef.
Here is an example of use:
<li Class="VFECore.WeatherLetterExtensions">
<letterDef>NeutralEvent</letterDef>
<letterTitle>Hail</letterTitle>
<letterText>Pellets of frozen rain fall from cumulonimbus clouds. Any person or creature not under the roof risks getting injured by them.</letterText>
</li>