Airborne Aviation Decoding a METAR

What is a METAR?

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:

METAR
METAR YSCN 052230Z AUTO 27016KT 9999NDV // BKN025 15/05 Q0997 RMK RF00.2/04.6
METAR


It is decoded as follows:

METAR
A routine observation when conditions are at or above specified levels.

In cases of low cloud, visibility or strong winds the observation will be identified as a SPECI.
YSCN
The location of the observation. (Camden)
052230Z
The origination date/time of the METAR which is given in UTC using a six figure group followed by the abbreviation Z ("Zulu").
AUTO
When included this indicates that the METAR only contains automated observations.

Some caution needs to be taken when interpreting automated visibility, weather and cloud information as they may not be equivalent to human observations.
27016KT
Wind direction in degrees true and speed in knots.
9999NDV
The visibility reported in metres.

When 9999 is indicated this means greater than 10km.

NDV means "no direction variable"
//
Element not available from an automated observation.

In this instance Weather (eg RA - Rain) is not available.
BKN025
Amount of cloud reported in hundreds of feet.

BKN025 = Broken cloud (5-7 OKTAS) at 2,500ft AGL.

If NCD is indicated this means "no cloud detected"
15/05
Temperature and dew point.
Q0997
QNH given as a four figure number.
RMK
Remarks

In this example they include Rainfall (RF) recorded in the 10 minutes prior to the observation in millimetres (0.2mm), and the rainfall recorded since 0900 local time (4.6mm).


Do all METARs look the same?

Here is an example METAR from Parkes (YPKS):

METAR YPKS 060000Z AUTO 20009KT //// // ////// 12/06 Q1024 RMK RF00.0/000.0


As you can see there are three elements not available:

  • Visibility
  • Weather
  • Cloud

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):

TTF METAR YMML 060030Z 24007KT 9999 BKN040 14/09 Q1021 RMK RF00.0/000.0
FM0100 27012KT 9999 LIGHT SHOWERS OF RAIN FEW020 BKN035


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) - see Decoding a 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)


More Information

More detailed information on METARs including all possible variations and codes can be found in AIP GEN 3.5 p3.3.
 

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This article was created 05-May-2010 and last updated 17-April-2014. Use of the information on this page is subject to the terms of use. Please report any errors to the webmaster.