This is the ((Storm index)) or storm index article template.
It can be used to mark a page as a set index article about named storms. A storm index article lists multiple storms, preferably with a description of their date and location.
This template is usually placed at the bottom of the page and adds the page to Category:Set index articles on storms.
This template can be used without any parameters like this:
((Storm index))
Editors may want to control how the page is sorted in Category:Set index articles on storms.
This is accomplished by adding the sort key as the "name=" parameter.
For example, List of storms named David is sorted using:
((Storm index|name=David))
or, in short:
((Storm index|David))