Originally Posted by
Stickshift3000
ATIS includes rainfall in the last 10 minutes, 1.6 mm in the opening post. I guess you could deduce from the definition of heavy rain (that you found) that 1.6 in 10 mins fits the definition.
Cloud size (rainfall area), wind speed (and gust) and droplet size are other variables that will influence visibility.
That’s not the ATIS, that’s the TTF METAR. The ATIS does not include the rainfall