A01 vs. A02 METARs

[[email protected]]

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!

[Scott Skylane]

wrote:
/snip/
> 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!
>
I believe an A01 station will not report the cause of the restriction to
visibility, just the visibility distance. An A02 station will report
what is causing the restriction, such as RA, SN, FG, BR, BLSN, HZ, etc.

Happy Flying!
Scott Skylane

[Steven P. McNicoll]

> 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.