Pilot's Weather Tools
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METAR/SPECI
A METAR is a routine report of meteorological conditions at an aerodrome.
A SPECI is a special report of meteorological conditions, issued when one or more elements meet specified criteria significant to aviation. SPECI is also used to identify reports of
observations recorded ten minutes following an improvement (in visibility, weather or cloud) to above SPECI conditions.
Location
The location is indicated by either the ICAO (International Civil Aviation Organization) location indicator or another approved abbreviation.
Date/Time
The day of month and the time of the report is given in UTC (Coordinated Universal Time) using six figures followed by the letter Z. The first two digits are the day of the month; the
following 4 digits are the time in hours and minutes, e.g. 291741Z (time of report is 1741 on the 29th of the month UTC).
AUTO
The abbreviation AUTO will be included when the report contains only automated observations.
Surface Wind
The wind direction is given in degrees true, rounded to the nearest 10 degrees. A variable wind direction is given as VRB.
The wind speed, given in knots (KT), is the mean value over the sampling period which is normally ten minutes. The maximum wind speed during the sampling period is reported
when it exceeds the mean speed by 10 knots or more. It is indicated by the letter G which is followed by the gust value, e.g. a wind direction of 280°, with a mean speed of 20 knots
and a maximum gust of 31 knots, is given as 28020G31KT.
Visibility
The horizontal visibility is given in metres up to 9000 metres; with 9999 being used to indicate a visibility of 10 kilometres or greater.
When the visibility is estimated manually (i.e. by an observer), two groups may be reported when the visibility is not the same in different directions. In these cases, the
higher visibility will be given first, followed by the minimum visibility and its direction (using one of the eight points of the compass) from the observing station e.g. 9000 2000N.
When visibility is given by an automated sensor (in fully AUTOmated reports), only one group is reported. The value is followed by the letters NDV (Nil Directional Variation) to
indicate that, as there is only one visibility sensor in place, any directional variation in visibility that may exist cannot be detected.
Weather
Weather phenomena are reported using the codes listed in the tables:
| Code |
Weather Descriptor |
| MI |
Shallow |
| BC |
patches |
| PR |
partial |
| DR |
drifting |
| BL |
blowing |
| SH |
showers |
| FZ |
freezing |
| TS |
thunderstorm |
| Code |
Weather Phenomena |
| DZ |
drizzle |
| RA |
rain |
| GR |
hail |
| SN |
snow |
| SG |
snow grains |
| DU |
dust |
| SA |
sand |
| SS |
sandstorm |
| DS |
dust storm |
| GS |
small hail/snow pellets |
| PL |
ice pellets |
| FG |
fog |
| BR |
mist |
| FU |
smoke |
| HZ |
haze |
| PO |
dust devil |
| SQ |
squall |
| FC |
funnel cloud |
| VA |
volcanic ash |
| IC |
ice crystals |
| PL |
ice pellets |
Intensity is indicated for precipitation, blowing dust/sand/snow, dust storm and sandstorm by appending:
- the prefix - for light, e.g. -DZ
- the prefix + for heavy, e.g. +RA
- no prefix for moderate, e.g. SHRA
One or more codes may be grouped, e.g. +TSGR, -TSRASN
NOTE
- When precipitation is reported with TS, the intensity indicator refers to the precipitation, e.g. -TSRA = thunderstorm with light rain.
- Well-developed dust/sand whirls (dust devils) and funnel clouds are reported using the indicator +
An observation may provide an indication of weather in the vicinity of the aerodrome, i.e. between 8 and 16KM of the aerodrome reference point. In these cases, the weather code is
prefixed with the abbreviation VC (vicinity), e.g. VCTS.
Cloud
Cloud information is reported from the lowest to the highest layers in accordance with the following rules:
- 1st group: the lowest layer regardless of amount.
- 2nd group: the next layer covering more than 2 oktas of the sky.
- 3rd group: the next higher layer covering more than 4 oktas of the sky.
- Extra groups: for cumulonimbus and/or towering cumulus clouds, whenever observed and not reported in any of the above.
Cloud amount is described using the codes in the table:
| Code |
Cloud Amount |
| SKC |
sky clear |
| FEW |
few (1 to 2 oktas) |
| SCT |
scattered (3 to 4 oktas) |
| BKN |
broken (5 to 7 oktas) |
| OVC |
overcast (8 oktas) |
| NSC |
nil significant cloud |
| NCD* |
nil cloud detected |
* NCD is reported (in fully automated reports only) when a cloud sensor detects nil cloud (a human observer will report SKC when the sky is clear.
Cloud height is given as a three-figure group in hundreds of feet above the aerodrome elevation, e.g. cloud at 700 feet is shown as 007.
Cloud type is identified only for cumulonimbus and towering cumulus, e.g. FEW030CB, SCT045TCU.
When an individual layer is composed of cumulonimbus and towering cumulus with a common base, the cloud is reported as CB only.
If the sky is obscured, due to, for example, bushfire smoke, human observers will report the vertical visibility (when it can be estimated) in lieu of cloud. It is reported
with the prefix VV followed by the vertical visibility in hundreds of feet, e.g. the group VV003 reports an estimated vertical visibility of between 300 and 399
feet (values are rounded down to the next hundred foot increment).
CAVOK
The abbreviation CAVOK (Cloud and Visibility OK) is used when the following conditions are observed simultaneously:
- Visibility is 10 kilometres or more;
- No cloud below 5000 feet or below the highest 25NM minimum sector altitude, whichever is the higher, and no cumulonimbus and no towering cumulus; and
- No weather of significance to aviation, i.e. none of the weather phenomena listed in the weather tables
above.
Temperature
Air temperature and dew point values are rounded to the nearest whole degree. Negative values are indicated by M (minus) before the numeral, e.g. 34/M04
Pressure (QNH)
The QNH value is rounded down to the next whole hectopascal and is given using four figures prefixed by Q, e.g. 999.9 is given as Q0999
Supplementary Information
Supplementary information is used to report:
- Recent Weather - significant weather observed since the last report but not at the time of observation is given after the prefix RE, e.g. RERA.
- Wind Shear - reports of wind shear experienced on take-off or landing are given after the indicator WS, e.g. WS RWY16.
Remarks
The Remarks section (indicated by RMK) may contain the following:
- Quantitative information on past rainfall is given in
millimetres in the form RFRR.R/RRR.R or RFRR.R/RRR.R/RRR.R. The former, e.g. RF00.2/004.2, gives the rainfall recorded in the ten minutes prior to the observation time, followed by the rainfall
recorded in the period since 0900 local time. The second format, e.g. RF00.2/003.0/004.2, gives the rainfall recorded in the ten minutes prior to the observation, followed by the rainfall in the
sixty minutes prior to the observation, followed by the rainfall recorded in the period since 0900 local time.
- Information of operational significance not reported in the body of the message, for example:
- information about significant conditions (such as bushfires and distant thunderstorms) beyond the immediate vicinity of the aerodrome,
- any BKN or OVC low or middle cloud present at or above 5000 feet when CAVOK has been included in the body of the message,
- CLD:SKY MAY BE OBSC may be reported in fully automated reports when the ceilometer (cloud sensor) detects nil cloud and the visibility sensor estimates horizontal visibility as
being less than 1000 metres
Elements of report not available
Where an element of a report is not available, solidi will be reported in lieu of the missing element, e.g. //// for visibility, // for weather and ////// for cloud.
SPECI Criteria
SPECI is used to identify reports of observations when conditions are below specified levels of visibility and cloud base; when certain weather phenomena are present; and when
temperature, pressure or wind change by defined amounts (outlined in the table on the right).
SPECI is also used to identify reports of observations recorded 10 minutes following an improvement in visibility, weather or cloud to METAR conditions.
| Element |
Criterion |
| Wind Direction |
Changes of 30° or more, the mean speed before or after the change being 20KT or more |
| Wind Speed |
Changes of 10KT or more, the mean speed before or after the change being 30KT or more |
| Wind Gust |
- Gusts of 10KT or more above a mean speed of 15KT or more
- Gust exceeds the last reported gust by 10KT or more
|
| Visibility |
When the horizontal visibility is below the aerodrome’s highest alternate minimum visibility* |
| Weather |
When any of the following begins, ends or changes in intensity:
- thunderstorm
- hailstorm
- mixed snow and rain
- freezing precipitation
- drifting snow
- fog (including shallow fog, fog patches and fog at a distance)
- dust storm
- sand storm
- squall
- funnel cloud
- moderate or heavy precipitation
|
| Cloud |
When there is BKN or OVC cloud below the aerodrome's highest alternate minimum cloud base* |
| Temperature |
When the temperature changes by 5°C or more since last report |
| Pressure |
When the QNH changes by 2hPa or more since last report |
| Other |
- Upon receipt of advice of the existence of wind shear
- The incidence of any other phenomenon likely to be significant
|
*Where no descent procedure is established for an aerodrome, the aerodrome’s alternate ceiling and visibility are 1500 feet and 8 kilometres respectively.
METAR/SPECI Examples
METAR YPPH 221130Z 28012G23KT 9000 -SHRA FEW005 BKN050 27/22
Q0999 RETS RMK RF00.6/003.4 DISTANT TS
| REPORT |
EXPLANATION |
| METAR |
Routine meteorological observation |
| YPPH |
ICAO location indicator for Perth Airport |
| 221130Z |
Time of observation is 1130 on the 22nd of the month UTC |
| 28012G23KT |
Wind from the west (280 degrees True) at 12 knots; gusting to 23 knots |
| 9000 |
Visibility is 9 kilometres. |
| -SHRA |
Present weather is light rain shower |
| FEW005 |
There are 1 to 2 oktas of cloud with base at 500 feet |
| BKN050 |
There are also 5 to 7 oktas of cloud with base at 5000 feet |
| 27/22 |
The air temperature is 27°C; the dewpoint temperature is 22°C |
| Q0999 |
The QNH is between 999 and 999.9 hectopascals |
| RETS |
Recent weather was a thunderstorm |
| RMK |
Remarks section follows |
| RF00.6/003.4 |
0.6 mm of rain has fallen in the last 10 minutes; 3.4 mm has fallen since 0900 local time |
| DISTANT TS |
Distant thunderstorm (greater than 16 kilometres from the aerodrome reference point) |
SPECI YSCB 171515Z AUTO 22015G25KT 9000NDV // NCD 13/09 Q1003 RMK
RF00.8/003.0
| REPORT |
EXPLANATION |
| SPECI |
Special meteorological observation (for wind gust) |
| YSCB |
ICAO location indicator for Canberra Airport |
| 171515Z |
Time of observation is 1515 on the 17th of the month UTC |
| AUTO |
This report is fully automated |
| 22015G25KT |
Wind from the southwest (220 degrees True) at 15 knots, gusting to 25 knots |
| 9000NDV |
Visibility is 9000 metres; from a single visibility sensor, therefore no directional variation (NDV) in visibility can be detected |
| // |
Present weather is unavailable |
| NCD |
Nil cloud has been detected (by ceilometer) |
| 13/09 |
The air temperature is 13°C; the dewpoint temperature is 09°C |
| OVC110 |
There are also 8 oktas of cloud with base at 11 000 feet |
| Q1003 |
The QNH is between 1003 and 1003.9 hectopascals |
| RMK |
Remarks section follows |
| RF00.8/003.0 |
0.8 mm of rain has fallen in the last 10 minutes; 3.0 mm has fallen since 0900 local time |
"Flying might not be all plain sailing, but the fun of it is worth the price."
- Amelia Earhart
|
About METARs
