A METAR is a routine observation (30 or 60 minuute intervals) when meteorological conditions are at or above specified levels. When conditions deteriorate below specified levels the observation is called a SPECI.
At major airports, a statement of trend, valid for three hours from the time of the observation, is appended to the observation. These are called Trend Type Forecasts (TTF) and will be shown as TTF METAR or TTF SPECI.
Decoding a METAR
Here is an example of a typical METAR:
It is decoded as follows:
Do all METARs look the same?
Here is an example METAR from Parkes (YPKS):
As you can see there are three elements not available:
It’s quite common for remote and regional aerodromes to not be equipped with an Automatic Weather Station (AWS) capable of determining these elements.
METARs that do not indicate AUTO are typically only found major airports like Sydney and Canberra. These observations will include detailed weather and cloud information (eg. TSRA SCT025CB) often include additional remarks (eg. Bush fire smoke).
Trend Type Forecast (TTF)
A Trend Type Forecast (TTF) is typically only issued at major airports.
In addition to the observation (METAR) a statement of trend, valid for three hours from the time of the observation, is appended to the observation. If there will be no trend in the remarks section of a TTF METAR will feature “NOSIG”.
Below is an example of a TTF METAR for Melbourne (YMML):
In addition to the human observation at 060030Z, 30 minutes later at 060100Z conditions are forecast to change. The forecast format is the same of that in a Terminal Area Forecast (TAF).
Obtaining a METAR
A METAR is included when you obtain a Terminal Area Forecast (TAF). You can obtain a TAF through the following methods:
Aerodrome Weather Information Service (AWIS)
Many aerodromes feature an Automatic Weather Information Service (AWIS) that provides information generated from the Automatic Weather Station (AWS) on a continuous basis.
AIP ERSA will contain details of an AWIS if available. For Camden (YSCN) the AWIS details are as follows:
- Phone 02 4655 9248 (24 hours)
- VHF 125.1 (Outside tower hours)