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Automated Weather Stations Weather Tutorial

In extreme conditions the Automated Weather Stations (AWS) ice up and can give anomolous readings. Following is a list of issues to be aware of:

Wind

The wind speed and direction is controlled by one of those devices that spin in the wind (ananometer) and in very cold conditions these can freeze up. Hence they can report the wind from the wrong direction and as nearly calm when in fact it is gale force! Be wary of any low wind readings when other indicators say it should be strong wind.

Precipitation since 9am

This is calculated from melted snow. The snow is collected in a heated bowl which melts the snow and is then read in mm of precipitation. In high wind or heavy snow the snow simply blows past the bowl and doesn't settle in it or it freezes over and hence can't record the full amount. AWS's are notorious for considerably under representing snowfall, especially if they are heavy falls or there is a high wind.

For other occassions then the standard conversion is approximately 1mm of precipitation results in 1cm of snow

Mean Surface (Sea) Level Pressure (MSLP)

This is calculated from the reading at the AWS and then corrected for altitude. It is unusual to report MSLP for the resorts as they are too high and errors creep into the correction. Approximations for MSLP can be obtained by looking at nearby lower level stations like Seymour, Albury and Cooma.

Locations of the resort AWS's

At the resorts each AWS is usually located near the summit. For these stations the altitude of the AWS are;
Baw Baw 1520m
Buller 1707m
Crackenback 1957m
Falls 1767m
Hotham 1849m