Meteorological Terminal Air Report
(METAR) – literally ‘Meteorological Terminal Air Report’ or more
straightforwardly ‘Routine aerodrome meteorological report’
The indicator group e.g. METAR,
SPECI, or TREND as appropriate. Where a number of METARs are issued in the same
bulletin, this, along with a date time group may be in the bulletin header.
The ICAO indicator of the reporting
station eg. EGLL.
Date/Time of Report
The day of the month and the time of
the observation in hours and minutes UTC e.g. 191350Z.
The optional code word AUTO indicates that the report has been generated using data from an automated observing system.
The mean wind direction in degrees
true to the nearest 10 degrees, from which the wind is blowing and the mean
wind speed in knots over the 10 minute period immediately preceding the
observation e.g. 35015KT = 350 degrees true/15 kts; VRB05KT = variable/5 kts;
00000 = CALM. If gusts exceed the mean wind speed by 10kts or more in the 10
minutes preceding the time of the report, a letter G and 2
more figures are added to indicate the maximum wind speed e.g. 23018G30KT = 230
degrees true/18 kts gusting to a maximum of 30 kts. Reports may
express wind speed in metres per second (‘MPS) or Kilometres per hour (KPH).
Winds greater than 100 kts or more shall be preceded by the
letter P and reported as P99KT or P99MPS or P199KPH.
Reported in a four figure group
(e.g. 0400 = 400 metres; 8000 = 8 km) up to but excluding 10 km; 9999 = 10km or
more; 0000 = less than 50 metres visibility.
Runway Visual Range (RVR)
- Aerodromes may include a letter
indicator R followed by the runway designator, a”/”
and the touchdown zone RVR in metres, e.g. R06/0400. If the RVR is assessed on
2 or more runways simultaneously then the RVR group will be repeated.
- Parallel runways will have L, C,
or R added to the runway designator e.g. R24L/1100.
- If the RVR is greater than the
maximum value that can be measured, P will precede this value
- If the RVR is less than the minimum
value that can be measured , M will precede this value e.g.
- If RVR trends can be measured
then U, D, or N will follow the RVR
value to indicate increasing, decreasing or no change respectively.
Weather is indicated by up to 3
groups comprising symbols and letters from the following:
|– = slight||+ = Heavy||BC = Patches||BL = Blowing|
|BR = Mist||DR = Low Drifting||DS = Dust Storm||DU = Widespread Dust|
|DZ = Drizzle||FG = Fog||FC = Funnel Cloud (e.g. Tornado)||FU = Smoke|
|FZ = Freezing||GR = Hail||GS = Small Hail||HZ = Haze|
|IC = Ice Crystals||MI = Shallow||PL = Ice Pellets||PO = Dust Devils|
|RA = Rain||SA = Sand||SG = Snow Grains||SH = Shower|
|SN = Snow||SQ = Squall||SS = Sandstorm||TS = Thunderstorm|
|VA = Volcanic Ash||VC = In the vicinity (nearby)||UP = Unidentified Precipitation||RE = Recent|
e.g – FZDZ = Slight Freezing Drizzle; + SHRASN = Heavy Shower of Rain and Snow; REUP = Recent Unidentified Precipitation.
Cloud amount is reported as FEW = few (1-2 oktas), SCT = scattered (3-4 oktas), BKN = broken (5-7 oktas) or OVC = overcast (8 oktas), followed by the height of the cloud base in hundreds of feet above aerodrome elevation e.g. SCT018 = scattered clouds at 1800 ft. Note that in area and route forecasts, heights are AMSL or standard pressure altitudes.
Selection of cloud layers reported
is made as follows:
- The lowest Layer;
- The next lowest layer of SCT or
- The next higher layer of BKN or
- Significant convective cloud (CB or TCU)
if not already reported.
Sky obscured is given as VV followed
by the vertical visibility in hundreds of feet. When the vertical visibility
has not been measured, the group will be VV///.
When there are no clouds of
operational significance to report, no CB or TCU and CAVOK is
not appropriate, the abbreviation NSC (No Significant Cloud)
The Visibility, Cloud, and Weather
groups are replaced by the term CAVOK (cloud and visibility
OK) when the following conditions exist simultaneously:
- Visibility is 10km or more.
- No CB or TCU and no cloud below 5000 feet or Minimum Sector Altitude (MSA) (whichever is the greater).
- No significant weather at or in the vicinity of the aerodrome.
Air temperature and dewpoint are reported in whole degrees Celsius, e.g. 10/07 = Temperature 10°C/ Dew point 7°C.
QNH is stated to the nearest whole hectopascal (equivalent to a millibar) rounded down and preceded by the letter Q e.g. Q1013 = QNH 1013 Hectopascals.
Significant recent weather observed in the period since the last routine observation will be reported by using the code letters for weather preceded by the letters RE e.g. RETS = Recent Thunderstorm.
In a METAR, civil aerodromes may include wind shear if reported along the take off or approach paths in the lowest 1600 ft with reference to the runway. WS is used to begin the group, e.g. WS TKOF RWY20. If the wind shear is affecting all runways, WS ALL RWY is reported.
Aerodrome Colour State
UK military and USAFE aerodromes
will include the abbreviated colour state at the end of the message and ad the
forecast colour state after the TREND.
Runway State Group (RSG)
An 8-figure group which may be added
to METAR from civil aerodromes.
- Runway designator (first two digits)
27 = Rwy
27 or 27L
77 = Rwy
27R (50 added to the designator for “right” runway)
88 = All
repetition of the last message as no new information received.
- Runway Deposits (third digit)
0 = Clear
1 = Damp
2 = Wet or
3 = Rime
or frost covered (depth normally less than 1mm)
4 = Dry
5 = Wet
6 = Slush
7 = Ice
compacted or rolled snow
9 = frozen
ruts or ridges
/ = type
of deposit not reported (e.g. due to rwy clearance in progress)
- Extent of runway contamination
1 = 10% or
2 = 11% to
5 = 26% to
9 = 51% to
/ = not
reported (e.g. due to rwy clearance in progress)
- Depth of Deposit
the quoted depth is the mean of a
number of readings or, if operationally significant, the greatest depth
00 = less
01 = 1mm
90 = 90mm
91 = not
92 = 10cm
93 = 15cm
94 = 20cm
95 = 25cm
96 = 30cm
97 = 35cm
98 = 40cm
Rwy(s) non-operational due to snow, slush, ice, large drifts or runway
clearance, but depth not reported.
// = depth
of deposit operationally not significant or measurable.
- Friction Coefficient or Braking
Action (seventh and eighth digits)
The mean value is transmitted or, if
operationally significant, the lowest value, e.g.:
28 = friction
friction coefficient 0.38
Braking action: Poor
Braking action: Medium/Poor
Braking action: Medium
Braking action: Medium/Good
Braking action: Good
Figures unreliable (e.g. if equipment has been used which does not measure
satisfactorily in slush or snow.)
Braking action not reported (e.g. runway not operational; aerodrome closed;
Note: If contamination conditions
cease to exist, the abbreviation CLRD is used, e.g.
Rwy 24 cleared; Braking action: Medium/Good
All rwys cleared; Braking Action: Good
TREND forecasts are indicated
by BECMG (Becoming) or TEMPO (temporary)
which may be followed by a time group (hours and minutes UTC) preceded by one
of the letter indicated FM (from), TL(until), AT (at)
e.g. BECMG FM1030 TL1130
NOSIG replaces the TREND group when
no significant changes are forecast to occur during the 2 hour forecast period.
To indicate the end of significant
weather the abbreviation NSW (No Significant Weather) is used.
Only those elements for which a
significant change is expected should be included in a TREND.