How to get Weather Warnings from Bing API Truck Route?

When requesting Truck Routes from this endpoint https://dev.virtualearth.net/REST/v1/Routes/Truck
, how do I enable Weather Warnings to be included in the response? Is there a certain parameter that needs to be included in the request? Is it dependent on some properties of the request object?
Also, what kind of weather warnings are returned when they are applicable? Is there a full list somewhere I can view?
I've tried calculating truck routes through area's that are experiencing extreme weather with active alerts, but I have yet to see any weather warnings returned in the Itinerary Items objects returned in the Truck Route response object.