Plain English Meaning

A part of an automated weather station that senses when something is falling from the sky and works out whether it is rain, snow, or another type of precipitation, so it can be reported correctly.

Full Definition

A sensor component on an automated weather station (such as ASOS) that detects whether precipitation is occurring and identifies its type — for example, distinguishing rain from snow — so that the correct precipitation indicator is reported in the METAR.

Context Anchor

Seen in METAR remarks, especially when interpreting AO1 and AO2 automated station codes.

Derivation

‘Discriminator’ comes from the Latin discriminare, meaning ‘to separate’ or ‘to distinguish between things.’ Here it tells one type of precipitation apart from another — it discriminates between rain and snow, not between people.