Flight Weather Reports METAR - Definitive Guide
Peter
Pete has been flying airplanes for 20 years. He has flown everything from light piston aircraft to heavy jets, both as first officer and captain. He is currently enjoying life piloting the Airbus A330 for a major international airline.
A METAR (Meteorological Terminal Air Report) is a routine flight weather report of actual conditions observed at an airport.
METARs report actual observed weather at an airport. METARs are encoded in an internationally understandable standard format. There are minor differences between US and international METARs, but the format is generally the same, using different units of measurement.
Index
How is a METAR decrypted?
Let's take the following example of a METAR we just received viaAutosfor Chicago O'Hare International:
- KORD 021651Z 260/14kt 10SM FEW250 29/17 A2988 RMK AO2 SLP112 T02940167 $
- season: For example. KORD is Chicago.
- airtime: 02165Z Date and time of issuance of the METAR in UTC (also known as 'Zulu' time), ie 021651Z means the second day of the month at 1651 Zulu time.
- wind direction and speed: 260/14KT Wind direction in METARs is true in degrees (ie referenced to true north as opposed to magnetic north). Wind speed is usually given in knots but can also be given in "MPS" (meters per second). In this case the wind is 260º true, at 14 knots.
- sight range: In the US, visibility is measured in statute miles (SM) and feet. 10SM is visibility of "10 mandatory miles or more").
- cloudy: FEW250 refers to low clouds at 25,000 feet.
Cloud cover is measured in "octas" or "eighths of the sky".
Few (few) = 1-2 oktas
Spread (SCT) = 3-4 octaves
Broken (BKN) = 5-7 oktas (so more than half the sky)
Cloudy (OVC) = 8 oktas (i.e. the sky is completely covered by clouds) - temperature and dew point: 29/17 The temperature (in degrees Celsius) is given first, followed by the dew point (the temperature at which the air would be saturated with water vapour). The dew point is also given in degrees Celsius.
- pressure at sea level: A2988 Refers to an altimeter setting in inches of mercury indicating QNH (ie altitude above sea level). In this case, if you set the altimeter to 29.88 when you are at the Chicago gate, it will read 668 feet (ie the height of Chicago O'Hare).
- RMC (Note):The comments section can contain many different elements. ThenAO2Tell us this METAR was recorded by an automated stationcoma precipitation discriminator. SLP112 gives us the pressure at sea level in millibars - in this case 1011.2Megabyte. (See David Werntz for a great explanation of SLPHere).T02940167gives us more accurate information about temperature and dew point: temperature of 29.4ºC and dew point of 16.7ºC.
METAR Decoding - Definitive List
| – | Luz | FRQ | frequently | REAL ACADEMY OF FINE ARTS | Regen |
| + | difficult | CAKE | Cake | IDT | routine late observation |
| p.s | maintenance control display | FU | smoke (French:Rauch) | Fan | reportable amount |
| CAC | Castilian altocumulus | FZ | Freeze | RVR | Visibility tells you |
| ACFT-MSHP | plane crash | FZRANO | Freezing rain sensor not available | RVRNR | RVR system stats not available |
| ACSL | Altocumulus permanent lenticular cloud | GRAMM | found | RWY | rail |
| ALPS | Airport location point | GRAMM | hail (French:greeting) | S | about him |
| ALQDS | all quadrants | SG | Granulated snow and/or small hail (French:Hagel) | one | Arena |
| ALQS | all quadrants | HLSTO | Hagel | SCSL | Persistent lenticular cloud stratocumulus |
| AO1 | automated station without precipitation discriminator | Hertz | confusion | SE | South East |
| AO2 | automated station with precipitation discriminator | TO | ice crystals | SFC | surface |
| APCH | getting closer | INCL | growing | SG | grains of snow |
| April | evident | INTMT | changing | Sch | have a shower |
| TAE | one | KT | us | speech therapist | sea level pressure |
| ATCT | Airport traffic control tower | TEAMS | last observation before a cover break at a hand station | SLPNO | Sea level pressure not available |
| AUTO | Fully automated report | LST | local standard time | SM | legal miles |
| B | started on time | GLT | beam | serial number | neu |
| BC | Parches (French: banks) | LWR | lower | SNINCR | Snow rises fast |
| study of law | Atem | METRO | less, less than | SO G | snow on the ground |
| BR | niebla (English: Brume) | max | maximal | SPECIES | an unscheduled bulletin after a significant change |
| California | Cloud Air Lightning | METRO | routine weather report provided at fixed intervals | QE | found |
| CB | Cumulonimbus Clouds | MI | shallow (French:chop) | SS | Sandsturm |
| CBMAM | a cumulonimbus cloud | MEIN. | Minimum | STN | season |
| CC | Cloud Cloud Lightning | MOVEMENT | moved / moved / moved | SO | on west |
| CCSL | Cirrocumulus from permanent lenticular clouds | MONTE | Berge | TCU | towering cumulus clouds |
| CD | Candela | Norte | Norte | TS | Sturm |
| C.G. | Lightning from cloud to earth | N / D | not applicable | TSNR | Storm information not available |
| CH | cloud height indicator | NO | Northeast- | TWR | Tower |
| Chino | Secondary location sky state not available | I checked it out | NOSPECIESReports are made on the station | A FOREIGN | a foreign |
| ZIG | Here | NO | northwest | ABOVE | unknown precipitation |
| OPPOSITES | Continuum | OCNL | occasionally | coordinated world time | coordinated world time |
| KOR | Correction to a previously posted comment | OHD | the overload | v | Variable |
| RD | low operation | GLB | one | Virginia | volcanic ash |
| SD | Sandsturm | PAG | greater than the highest reportable amount | CV | Fence |
| DSIPTG | distracting | PCPN | precipitation | VIS | sight range |
| DSNT | removed | PK WND | top wind | ALT | Secondary location visibility is not available |
| VON | widespread dust | ES | pieces of ice | Fan | Alcance visuell |
| DVR | clear line of sight | PNO | Rainfall not available | VRB | Variable |
| DZ | drizzle | AFTER | Dust (French:Staub) or blown sand | C | west |
| mi | this, completed on time, estimated upper limit | public relation | partially | WND | Wind |
| FC | funnel cloud | GIFT | SW | wind shear | |
| FG | Fog | PRESFR | the pressure drops quickly | WSHFT | wind change |
| FIRST | first observation after a break in coverage at the hand station | PRESRR | Pressure increases rapidly | Z | Zulu/UTC |
| VON | Ice on the meter | PWINO | Rainfall detection sensor not available | ||
| FROPA | front passage | py | spray |
PDF METAR and TAF decodingDispose
How long are METARs valid?
US METARs are valid for one hour and are issued every hour.
In other countries, METARs are typically valid for 30 minutes and are issued twice an hour: 20 minutes past the hour and 50 minutes past the hour.
A SPECI is issued for significant changes since the publication of a METAR.
Related: Aviation SPECI Reports: A Guide for Pilots
What does $ mean in a METAR?
The $ indicates that the automated system requires maintenance. Sometimes the RMK (Observations) section of the METAR includes a maintenance status indicator.
METAR health status indicators
| METAR RMK | sensor failure |
| CRAZY CHILD | ceiling height sensor |
| FZRABI | Eisregensensor |
| PNO | rain gauge |
| PWINO | current time display |
| RVRNR | If the RVR is missing and would normally be reported |
| TSNR | lightning detection system |
| VISNO ORT | Secondary visibility sensor |
Flight categories of aviation
In the United States, METARs can be truncated to show the possible flight time at an airport in terms of ceiling and visibility. The four aviation flight categories are:
- VFR:Visibility greater than 5 miles and ceiling greater than 3000 feet.
- Boundary VFR:Visibility between 3 and 5 miles and/or ceiling between 1000 feet and 3000 feet.
- IFR:Visibility of 1 mile or more but less than 3 miles and/or ceiling of 500 feet or more but less than 1000 feet.
- Low IFR:Visibility less than 1 mile and/or ceiling less than 500 feet.
Trend Type Forecast
A trend forecast, or simply a "trend", is a two-hour forecast attached to a METAR or SPECI.
Trend type prediction example: TEMPO 3SM VCSH = Temporary visibility of 3 legal miles, with showers in close proximity (between 5 and 10 nm from airport).
What are the differences between METAR and TAF?
A METAR is an Air Terminal Weather Report (or "Routine Aviation Weather Report") is a weather report of actual conditions at an airport at a specific time.
A TAF (Terminal Area Forecast) is a weather forecast for a specific area around the airport specified in the forecast.
So the main difference between the two is that METARs are a record of actual conditions while TAFs are a prediction of future weather.
Another difference is that METARs may include a Notes section (RMK). The observations may include a more accurate temperature, sea level pressure (SLP), or runway condition group (e.g., if the runway is contaminated with snow).
TAF, METER inSPECIESUse a common code to describe the weather, e.g. B. TS for thunderstorms or SHRA for showers.
Frequently asked questions about METARs.
Are the winds in the METARs true in degrees or magnetic?
Wind direction in METAR and TAF is in true degrees.
What does the term METAR mean?
A METAR (Meteorological Terminal Air Report) is a routine flight weather report of actual conditions observed at an airport.
Where can you get METARs?
For example, we can receive METARROS in many places: if it is on the air, we can receive it by emailACARS/Datalink, they are available online (e.g. in theNOAA Aviation Weather Center) or through applications such asarc flightÖAeroTime.
When are METARs issued?
In the United States, METARs are generally issued once every hour, 55 minutes past the hour. In other states, they are usually broadcast twice an hour, at 20 minutes past the hour and 50 minutes past the hour.
What does NPC mean in a METAR?
NSC stands for "No Significant Cloud" and is used when no cloud is observed.
What does NCD mean in a METAR?
NCD stands for "No Cloud Perceptible" and is issued when no cloud is detected by an automatic reporting point.
What does NDV mean in a METAR?
NDV stands for No Directional Variation and is used when visibility has been automatically captured by a single sensor. Since only one sensor was used, it cannot determine any change in visibility.
What does 9999 mean in a METAR?
9999 refers to a visibility of 10,000 m or more.
What does a V in a METAR mean?
V stands for "variable" and refers to the wind direction. For example, a METAR 030/15 010V060 means that the prevailing wind is 030º at 15 knots, varying in direction from 010º to 060º.
What is the difference between SKC and CLR?
Both SKC and CLR represent clear skies, with SKC being used by manual stations and CLR being issued by automatic stations, indicating no cloud layer was detected at or below 12,000 feet.
What does VV or VV/// mean in a METAR?
VV stands for "vertical visibility" and means that the sky is obscured by surface phenomena (e.g. fog); The three digits after VV indicate altitude in hundreds of feet. VV/// means vertical visibility is of indefinite height.
What does a P in a METAR mean?
A P means greater than the highest reportable value. For example, P6SM means visibility greater than 6 statutory miles.
What is CAVOK in flight climate?
CAVOK stands for "Correct Ceiling and Visibility" and means no clouds below 5,000 feet, no cumulonimbus (CB) or high cumulus (TCU) at any level and a visibility of 10 km/6 nm or more.
What does VC mean in METARs?
VC stands for "neighborhood" and refers to the weather near the airport but not inside. For example, VCSH means rain showers near the airport.
"Weather phenomena occurring behind the observation point (between 5 and 10 nm) are coded as nearby (VC)" [FAA Advisory Circular - Aviation Weather Services 3.1.5.8.2]
Are the cloud heights in the METAR AGL or MSL?
METARs refer to altitudes above the airport i.e. AGL.
What does SPECI mean in a METAR?
SPECI refers to a specific update of a METAR when a significant change has occurred since the METAR was published.Learn more about SPECI here.
How often are TAFs issued?
TAFs are issued 4 times a day at 6-hour intervals. 0500z, 1100z, 1700z and 2300z valid for 30 hours.
What is a ceiling in aviation?
An upper limit is when the sky is darkened by five eighths (i.e. 5 oktas) of sky or more, i.e. H. broken clouds (BKN) or overcast (OVC).
When are TAFs issued?
TAFs are normally broadcast 4 times a day starting at 05:00 and reissued every 6 hours (05:00, 11:00, 17:00, 23:00).
When are METARs issued?
METARs are generally issued once an hour in the US and twice an hour internationally: 20 minutes before the hour and 50 minutes after the hour.
Where can I get more information about flying weather?
FAA Advisory Circular – Flugwetterdienste
Featured image: jvinals/Unsplash
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Peter
Pete has been flying airplanes for 20 years. He has flown everything from light piston aircraft to heavy jets, both as first officer and captain. He is currently enjoying life piloting the Airbus A330 for a major international airline.