We all know that it's important to give pilot reports when we can. Did you know that ATC is required to request a pilot report when the following conditions are observed or forecast? (Details Here)
1) Ceilings at or below 5,000 feet. These PIREPs shall include cloud base/top reports when feasible.
2) Visibility (surface or aloft) at or less than 5 miles.
3) Thunderstorms and related weather.4) Moderate or greater turbulence.
4) Moderate or greater turbulence.