# What does AO2 in the remarks of an ASOS/AWOS mean?

I occasionally see AO2 in the remarks of an automated weather report. What does the AO2 mean?

METAR KSLC 280453Z 00000KT 10SM FEW042 SCT055 BKN080 04/02 A2981 RMK AO2 CIG 037 NW RNWY SLP087 T00440022

The AO2 notation means the station is automated and has a precipitation discriminator. AO1 means automated but no precipitation discriminator. The precipitation discriminator will be able to sense the difference between rain and snow.
• I'd like to suggest that the first paragraph of this answer is not entirely correct. An automated station denoted AO1 in the remarks section of the METAR would still have a precipitation "sensor" but would not be able to discriminate between the types of precipitation (ex.: rain or snow). – Porcupine911 Feb 4 '16 at 15:28