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Old April 30th 06, 10:25 PM posted to rec.aviation.ifr
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Default A01 vs. A02 METARs


wrote in message
ups.com...

Regarding AUTOmated METARs, the AIM says there are two different kinds
of automated stations: "AO1 for automated weather reporting stations
without a precipitation discriminator, and AO2 for automated stations
with a precipitation discriminator. (A precipitation discriminator can
determine the difference between liquid and frozen/freezing
precipitation). This information appears in the remarks section of an
automated report. "

Does anyone know the practical use of this nugget of AO1/AO2
information? For example, does it mean that an AO1 station reports -RA
for light rain OR light snow? Thanks!


It reports whatever type of precipitation is present, if it can make that
determination. Sometimes it reports UP, unknown precipitation.