METAR

Last updated
A METAR processing and transmitting unit installed at Pittsburgh-Butler Regional Airport, United States METAR processing machine at KBTP.jpg
A METAR processing and transmitting unit installed at Pittsburgh-Butler Regional Airport, United States

METAR is a format for reporting weather information. A METAR weather report is predominantly used by aircraft pilots, and by meteorologists, who use aggregated METAR information to assist in weather forecasting.

Contents

Raw METAR is the most common format in the world for the transmission of observational weather data.[ citation needed ] It is highly standardized through the International Civil Aviation Organization (ICAO), which enables it to be understood throughout most of the world.

Report names

In its publication the Aeronautical Information Manual (AIM), the United States Federal Aviation Administration (FAA) describes the report as aviation routine weather report, [1] while the international authority for the code form, the World Meteorological Organization (WMO), describes it as the aerodrome routine meteorological report. The National Oceanic and Atmospheric Administration (part of the United States Department of Commerce) and the United Kingdom's Met Office both employ the definition used by the FAA. METAR is also known as Meteorological Terminal Aviation Routine Weather Report [2] or Meteorological Aerodrome Report. [3]

Frequencies and types

METARs typically come from airports or other permanent weather observation stations. Reports are generated once an hour or half-hour at most stations, but if conditions change significantly at a staffed location, a report known as a special (SPECI) may be issued. [4] :2 [note 1] Some stations make regular reports more frequently, such as Pierce County Airport (ICAO code: KPLU) which issues reports three times per hour. [5] In addition to METARs and SPECIs, ASOS One-Minute Observations (OMO) are updated once a minute. OMOs can be in various formats, including the METAR format. [4] :3

Some METARs are encoded by automated airport weather stations located at airports, military bases, and other sites. Some locations still use augmented observations, which are recorded by digital sensors, encoded via software, and then reviewed by certified weather observers or forecasters prior to being transmitted. Observations may also be taken by trained observers or forecasters who manually observe and encode their observations prior to transmission. In the United States, prior to mid-1990s, most observations are made manually, but today the vast majority are automated or augmented observations. [4] :2

History

The METAR format was introduced internationally on 1 January 1968, and has been modified a number of times since. North American countries continued to use a Surface Aviation Observation (SAO) for current weather conditions until 1 June 1996, when this report was replaced with an approved variant of the METAR agreed upon in a 1989 Geneva agreement. The WMO's publication No. 782 "Aerodrome Reports and Forecasts" contains the base METAR code as adopted by the WMO member countries. [6]

Information contained in a METAR

A typical METAR contains data for the airport identifier, time of observation, wind direction and speed, visibility, current weather phenomena such as precipitation, cloud cover and heights, temperature, dew point, and barometric pressure. This information forms the body of the report, consisting a maximum of 11 groups of information. [4] :5 A METAR may also contain information on precipitation amounts, lightning, and other information that would be of interest to pilots or meteorologists such as a pilot report or PIREP, colour states and runway visual range (RVR). These may be provided in coded or plain language and appended to the end of the METAR as remarks. [4] :6

In addition, a short period forecast called a TREND may be added at the end of the METAR covering likely changes in weather conditions in the two hours following the observation. These are in the same format as a Terminal Aerodrome Forecast (TAF).

The complement to METARs, reporting forecast weather rather than current weather, are TAFs. METARs and TAFs are used in VOLMET broadcasts.

Cloud reporting

Cloud coverage is reported by the number of "oktas" (eighths) of the sky that is occupied by cloud. Automated substation substitutes time averaging of sensor data gathered during 30-minute period prior to reporting. [4] :2,4

This is reported as: [7]

Cloud coverage codes
AbbreviationMeaning
SKC"No cloud/Sky clear" used worldwide but in North America is used to indicate a human generated report [8] [9]
NCD"Nil Cloud detected" automated METAR station has not detected any cloud, either due to a lack of it, or due to an error in the sensors
CLR"No clouds below 12,000 ft (3,700 m) (US) or 25,000 ft (7,600 m) (Canada)", used mainly within North America and indicates a station that is at least partly automated [8] [9]
NSC"No (nil) significant cloud", i.e., none below 5,000 ft (1,500 m) and no TCU or CB. Not used in North America.
FEW"Few" = 1–2 oktas
SCT"Scattered" = 3–4 oktas
BKN"Broken" = 5–7 oktas
OVC"Overcast" = 8 oktas, i.e., full cloud coverage
TCU Towering cumulus cloud, e.g., SCT016TCU
CB Cumulonimbus cloud, e.g., FEW015CB
VV"Vertical visibility" = clouds cannot be seen because of fog or heavy precipitation, so vertical visibility is given instead.

The following codes identify the cloud types used in the 8/nnn part of RMK. [10]

WMO codes for cloud types
CodeLow cloudsMiddle cloudsHigh clouds
0nonenonenone
1 Cumulus
(fair weather)
Altostratus
(thin)
Cirrus
(filaments)
2 Cumulus
(towering)
Altostratus
(thick)
Cirrus
(dense)
3 Cumulonimbus
(no anvil)
Altocumulus
(thin)
Cirrus
(often with cumulonimbus)
4 Stratocumulus
(from cumulus)
Altocumulus
(patchy)
Cirrus
(thickening)
5 Stratocumulus
(not cumulus)
Altocumulus
(thickening)
Cirrus / cirrostratus
(low in sky)
6 Stratus or Fractostratus
(fair)
Altocumulus
(from cumulus)
Cirrus / cirrostratus
(hi in sky)
7 Fractocumulus / fractostratus
(bad weather)
Altocumulus
(with altocumulus,
altostratus, nimbostratus)
Cirrostratus
(entire sky)
8 Cumulus and stratocumulus Altocumulus
(with turrets)
Cirrostratus
(partial)
9 Cumulonimbus
(thunderstorm)
Altocumulus
(chaotic)
Cirrocumulus or
Cirrocumulus / cirrus / cirrostratus
/not validabove overcastabove overcast

Wind reporting

Wind observation measures the horizontal vector component of the wind, which includes both direction and speed. These are determined by evaluating the measurement over a 2-minute period. [4] :24–10

The wind direction is coded with the first three digits in tens of degrees relative to the true north. If wind speed is less than or equal to 6 kn (11 km/h; 6.9 mph), the wind direction will be displayed as variable or "VRB". If the wind speed is greater than 6 knots, but the direction varies more than 60° in the past 2 minutes, METAR will report the range of wind direction. For example, 21010KT 180V240 suggests the wind was variable from 180° to 240° at 10 knots. [4] :10

Immediately after the wind direction is the wind speed, coded in two or three digits measured in knots, km/h or m/s. If during past 10 minutes, the weather station detects more than 10 kn (19 km/h; 12 mph) between minimum and maximum windspeed, METAR determines a wind gust exists and reports the maximum instantaneous windspeed. [4] :10

If the air is motionless, the wind will be reported as calm and coded as 00000KT. [4] :10

Visibility and runway visual range

Visibility measures the atmospheric opacity. It is the greatest distance where at least half of the horizon circle can be seen from the surface. [4] :11

Runway visual range (RVR) is an instrument-derived measurement that suggests the horizontal distance an observer may see down the runway. In the US, for stations with RVR reporting capacity, this information is omitted from the METAR unless the visibility is at or below 1 mi (1.6 km), or the designated instrument runway's RVR is at or below 6,000 ft (1,800 m). RVR of up to four designated runways may be reported, depending on the country. [4] :11

Regulations and conventions

METAR code is regulated by the World Meteorological Organization in consort with the International Civil Aviation Organization. In the United States, the code is given authority (with some US national differences from the WMO/ICAO model) under the Federal Meteorological Handbook No. 1 (FMH-1), which paved the way for the US Air Force Manual 15-111 [11] on Surface Weather Observations, being the authoritative document for the US Armed Forces. A very similar code form to the METAR is the SPECI. Both codes are defined at the technical regulation level in WMO Technical Regulation No. 49, Vol II, which is copied over to the WMO Manual No. 306 and to ICAO Annex III.

Although the general format of METARs is a global standard, the specific fields used within that format vary somewhat between general international usage and usage within North America. Note that there may be minor differences between countries using the international codes as there are between those using the North American conventions — ICAO allows member countries to modify METAR code for use in their particular countries, as long as ICAO is notified. [4] :5

Examples

The two examples which follow illustrate the primary differences between the international and the North American METAR variations. [10] [12] [ page needed ]

International METAR codes

The following is an example METAR from Burgas Airport in Burgas, Bulgaria. It was taken on 4 February 2005 at 16:00 Coordinated Universal Time (UTC).

METAR LBBG 041600Z 12012MPS 090V150 1400 R04/P1500N R22/P1500U +SN BKN022 OVC050 M04/M07 Q1020 NOSIG 8849//91=

North American METAR codes

North American METARs deviate from the WMO (who write the code on behalf of ICAO) FM 15-XII code. Details are listed in the FAA's Aeronautical Information Manual (AIM), but the non-compliant elements are mostly based on the use of non-standard units of measurement. This METAR example is from Trenton-Mercer Airport near Trenton, New Jersey, and was taken on 5 December 2003 at 18:53 UTC.

METAR KTTN 051853Z 04011KT 1/2SM VCTS SN FZFG BKN003 OVC010 M02/M02 A3006 RMK AO2 TSB40 SLP176 P0002 T10171017= [14]

Note that what follows are not part of standard observations outside of the United States and can vary significantly.

In Canada, RMK is followed by a description of the cloud layers and opacities, in eighths (oktas). For example, CU5 would indicate a cumulus layer with 58 opacity. [16]

Flight categories in the US

METARs can be expressed concisely using so-called aviation flight categories, which indicates what classes of flight can operate at each airport by referring to the visibility and ceiling in each METAR. Four categories are used in the US: [17]

METARS expressed as US flight categories
CategoryVisibilityCeiling
VFR > 5 miand > 3000 ft AGL
Marginal VFRBetween 3 and 5 miand/or between 1,000 and 3,000 ft AGL
IFR 1 mi or more but less than 3 miand/or 500 ft or more but less than 1,000 ft
Low IFR< 1 miand/or < 500 ft

METAR weather codes

METAR abbreviations used in the weather and events section. Remarks section will also include begin and end times of the weather events. [10] Codes before remarks will be listed as "-RA" for "light rain". Codes listed after remarks may be listed as "RAB15E25" for "Rain began at 15 minutes after the top of the last hour and ended at 25 minutes after the top of the last hour."

Combinations of two precipitation types are accepted; e.g., RASN (rain and snow mixed), SHGSSN etc. If more than one type of weather is present, METAR will report in the following order: [4] :13

  1. Tornadic activity
  2. Thunderstorm
  3. Most dominating weather
  4. Precipitation
  5. Obscuration
TypeAbbr.Meaning
Intensity-Light intensity
Intensity(blank)Moderate intensity
Intensity+Heavy intensity
DescriptorVCIn the vicinity (5–10 mi / 8–16 km from station); visible phenomena:

TS, SH, FG, DS, SS, VA, PO, FC, BLSN, BLDU, BLSA

DescriptorRERecent hour's most important past phenomenon with residues:

TS, RA, FZRA, SN, BLSN, GR, GS, PL (e.g.:METAR ... Q1010 RERA=)

DescriptorMIShallow [French: Mince] (fog descriptor)
DescriptorPRPartial (fog descriptor)
DescriptorBCPatches [French: Bancs] (fog descriptor)
DescriptorDRLow drifting below eye level; including: DRSN, DRSA, DRDU
DescriptorBLBlowing at or above eye level; including: BLSN, BLSA, BLDU
Descriptor*SH Showers (*also without precipitation: VCSH)
Descriptor*TS Thunderstorm (*also without precipitation: VCTS, RETS or as thunder)
DescriptorFZFreezing; including: FZDZ, FZRA, FZFG
PrecipitationDZ Drizzle
PrecipitationRA Rain
PrecipitationSN Snow (snowflakes)
PrecipitationSG Snow grains
PrecipitationGS Graupel [French: Grésil], snow pellets and/or small hail (not in the US). [note 3] [18] Elsewhere hail is GR when it is 5 mm or greater [19] Outside of the US when the hail is less than 5 mm the code GS is used. [19] )
PrecipitationGR Hail [French: Grêle] (in the US includes small hail) [note 3]
PrecipitationPL Ice pellets
PrecipitationIC Ice crystals
PrecipitationUPUnknown precipitation
ObscurationFG Fog (visibility less than 1 km)
ObscurationBR Mist [French: Brume] (due to water droplets, visibility between 1 and 5 km) [note 4]
ObscurationHZ Haze (due to dry particulates, visibility between 1 and 5 km) [note 4] [4] :3
ObscurationVAVolcanic ash
ObscurationDUWidespread dust
ObscurationFUSmoke [French: Fumée]
ObscurationSASand
ObscurationPYSpray, only coded as BLPY
OtherSQ Squall
OtherPODust [French: Poussière] or sand whirls
OtherDS Duststorm
OtherSS Sandstorm
OtherFC Funnel cloud
TimeBBegan at time
TimeEEnded at time
Time2 digitsMinutes of current hour
Time4 digitsHour/minutes Zulu time

US METAR abbreviations

The following METAR abbreviations are used in the United States; some are used worldwide: [10]

METAR and TAF abbreviations and acronyms:

AbbreviationMeaningAbbreviationMeaning
$maintenance check indicator/indicator that visual range data follows; separator between temperature and dew point data.
ACC altocumulus castellanus ACFT MSHPaircraft mishap
ACSLaltocumulus standing lenticular cloud ALPairport location point
ALQDSall quadrants (official)ALQSall quadrants (unofficial)
AO1automated station without precipitation discriminatorAO2automated station with precipitation discriminator
APCHapproachAPRNTapparent
APRXapproximatelyATCTairport traffic control tower
AUTOfully automated reportCcenter (with reference to runway designation)
CAcloud-air lightning CB cumulonimbus cloud
CBMAMcumulonimbus mammatus cloud CCcloud-cloud lightning
CCSL cirrocumulus standing lenticular cloud cd candela
CGcloud-ground lightningCHIcloud-height indicator
CHINOsky condition at secondary location not availableCIGceiling
CONScontinuousCORcorrection to a previously disseminated observation
DOC Department of Commerce DOD Department of Defense
DOT Department of Transportation DSIPTGdissipating
DSNTdistantDVRdispatch visual range
Eeast, ended, estimated ceiling (SAO)FAA Federal Aviation Administration
FIBIfiled but impracticable to transmitFIRSTfirst observation after a break in coverage at manual station
FMH-1Federal Meteorological Handbook No.1, Surface Weather Observations & Reports (METAR)FMH2Federal Meteorological Handbook No.2, Surface Synoptic Codes
FROPA frontal passageFROINfrost on the indicator
FRQfrequentFT feet
FZRANOfreezing rain sensor not availableGgust
HLSTOhailstoneICAO International Civil Aviation Organization
INCRGincreasingINTMTintermittent
KT knots Lleft (with reference to runway designation)
LASTlast observation before a break in coverage at a manual stationLSTlocal standard time
LTG lightning LWRlower
Mminus, less thanMAXmaximum
METARroutine weather report provided at fixed intervalsMINminimum
MOVmoved/moving/movementMT mountains
NnorthN/Anot applicable
NCDC National Climatic Data Center NEnortheast
NOS National Ocean Service NOSPECIno SPECI reports are taken at the station
NOTAM Notice to Airmen NWnorthwest
NWS National Weather Service OCNLoccasional
OFCMOffice of the Federal Coordinator for MeteorologyOHDoverhead
OVRoverPindicates greater than the highest reportable value
PCPN precipitation PK WNDpeak wind
PNOprecipitation amount not availablePRES pressure
PRESFR pressure falling rapidlyPRESRR pressure rising rapidly
PWINOprecipitation identifier sensor not availableRright (with reference to runway designation), runway
RTDRoutine Delayed (late) observationRVreportable value
RVR Runway visual range RVRNO RVR system values not available
RWY runway Ssouth
SCSL stratocumulus standing lenticular cloud SEsoutheast
SFCsurface, i.e., ground level)SLP sea-level pressure
SLPNO sea-level pressure not availableSM statute miles
SNINCRsnow increasing rapidlySOGsnow on the ground
SPECIan unscheduled report taken when certain criteria have been metSTNstation
SWsouthwestTCU towering cumulus
TS thunderstorm TSNO thunderstorm information not available
TWR tower UNKNunknown
UTC Coordinated Universal Time Vvariable
VIS visibility VISNOvisibility at secondary location not available
VRvisual rangeVRBvariable
WwestWG/SOWorking Group for Surface Observations
WMO World Meteorological Organization WND wind
WS wind shear WSHFTwind shift
ZZulu, i.e., Coordinated Universal Time

US METAR numeric codes

Additional METAR numeric codes listed after RMK. [10]

CodeDescription
112346-hour maximum temperature. Follows RMK with five digits starting with 1. Second digit is 0 for positive and 1 for negative. The last 3 digits equal the temperature in tenths.

This example value equals −23.4 °C (−10 °F).

201236-hour minimum temperature. Follows RMK with five digits starting with 2. Second digit is 0 for positive and 1 for negative. The last 3 digits equal the temperature in tenths.

This example value equals 12.3 °C (54 °F).

4/012Total snow depth in inches. Follows RMK starting with 4/ and followed by 3 digit number that equals snow depth in inches.

This example value equals 12 inches of snow currently on the ground.

40234012324-hour maximum and minimum temperature. Follows RMK with nine digits starting with 4. The second and sixth digit equals 0 for positive for 1 for negative. Digits 3–5 equal the maximum temperature in tenths and the digits 7–9 equals the minimum temperature in tenths.

This example value equals 23.4 °C (74 °F) and 12.3 °C (54 °F).

520063-hour pressure tendency. Follows RMK with 5 digits starting with 5. The second digit gives the tendency. In general 0–3 is rising, 4 is steady and 5–8 is falling. The last 3 digits give the pressure change in tenths of a millibar in the last 3 hours.

This example indicates a rising tendency of 0.6 millibars (0.018 inHg). [20]

601233- or 6-hour precipitation amount. Follows RMK with 5 digits starting with 6. The last 4 digits are the inches of rain in hundredths. If used for the observation nearest to 00:00, 06:00, 12:00, or 18:00 UTC, it represents a 6-hour precipitation amount. If used in the observation nearest to 03:00, 09:00, 15:00 or 21:00 UTC, it represents a 3-hour precipitation amount.

This example shows 1.23 inches (31 mm) of rain.

7024624-hour precipitation amount. Follows RMK with 5 digits starting with 7. The last 4 digits are the inches of rain in hundredths.

This example shows 2.46 inches (62 mm) of rain.

8/765Cloud cover using WMO code. Follows RMK starting with 8/ followed by a 3 digit number representing WMO cloud codes.
98060Duration of sunshine in minutes. Follows RMK with 5 digits starting with 98. The last 3 digits are the total minutes of sunshine.

This example indicates 60 minutes of sunshine.

931222Snowfall in the last 6 hours. Follows RMK with 6 digits starting with 931. The last 3 digits are the total snowfall in inches and tenths.

This example indicates 22.2 inches (560 mm) of snowfall.

933021Liquid water equivalent of the snow (SWE). Follows RMK with 6 digits starting with 933. The last 3 digits are the total inches in tenths.

This example indicates 2.1 inches (53 mm) SWE.

See also

Notes

  1. Criteria for issuing a SPECI includes beginning or ending of hazardous weather, aircraft mishap, decreasing visibility or ceiling, or any other condition deemed critical by the observer of the responsible agency. [1]
  2. Precipitation discriminators are electrically heated at sub-freezing temperatures to calculate the water equivalent of frozen precipitation and snow accumulation.
  3. 1 2 In the US small hail is included with regular hail and the Remarks section is used saying "GR LESS THAN 1/4".
  4. 1 2 If the difference between temperature and dewpoint is less than or equal to 2°C, the station reports the condition as haze; else mist is reported.

Related Research Articles

<span class="mw-page-title-main">Weather station</span> Facility for atmospheric research and prediction

A weather station is a facility, either on land or sea, with instruments and equipment for measuring atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include temperature, atmospheric pressure, humidity, wind speed, wind direction, and precipitation amounts. Wind measurements are taken with as few other obstructions as possible, while temperature and humidity measurements are kept free from direct solar radiation, or insolation. Manual observations are taken at least once daily, while automated measurements are taken at least once an hour. Weather conditions out at sea are taken by ships and buoys, which measure slightly different meteorological quantities such as sea surface temperature (SST), wave height, and wave period. Drifting weather buoys outnumber their moored versions by a significant amount.

<span class="mw-page-title-main">National Weather Service</span> U.S. forecasting agency of the National Oceanic and Atmospheric Administration

The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the purposes of protection, safety, and general information. It is a part of the National Oceanic and Atmospheric Administration (NOAA) branch of the Department of Commerce, and is headquartered in Silver Spring, Maryland, within the Washington metropolitan area. The agency was known as the United States Weather Bureau from 1891 until it adopted its current name in 1970.

Automatic terminal information service, or ATIS, is a continuous broadcast of recorded aeronautical information in busier terminal areas. ATIS broadcasts contain essential information, such as current weather information, active runways, available approaches, and any other information required by the pilots, such as important NOTAMs. Pilots usually listen to an available ATIS broadcast before contacting the local control unit, which reduces the controllers' workload and relieves frequency congestion. ATIS was developed and adopted by the FAA in the mid-1960s and internationally beginning in 1974. Before the adoption of ATIS, this information was routinely disseminated to each aircraft separately, increasing controller workload during periods of high traffic density.

In meteorology and aviation, terminal aerodrome forecast (TAF) is a format for reporting weather forecast information, particularly as it relates to aviation.

<span class="mw-page-title-main">Runway visual range</span> Measure of aircraft visual distance

In aviation, the runway visual range (RVR) is the distance over which a pilot of an aircraft on the centreline of the runway can see the runway surface markings delineating the runway or the lights delineating the runway or identifying its centre line. RVR is normally expressed in meters or feet. RVR is used to determine the landing and takeoff conditions for aircraft pilots, as well as the type of operational visual aids used at the airport.

A pilot report or PIREP is a report of actual flight or ground conditions encountered by an aircraft. Reports commonly include information about atmospheric conditions or airport conditions. This information is usually relayed by radio to the nearest ground station, but other options also exist in some regions. The message would then be encoded and relayed to other weather offices and air traffic service units.

SYNOP is a numerical code used for reporting weather observations made by staffed and automated weather stations. SYNOP reports are typically sent every six hours by Deutscher Wetterdienst on shortwave and low frequency using RTTY. A report consists of groups of numbers describing general weather information, such as the temperature, barometric pressure and visibility at a weather station. It can be decoded by open-source software such as seaTTY, metaf2xml or Fldigi.

In aviation meteorology, a trend type forecast (TTF), also known simply as a trend, is a weather forecast written by a person on location at a major airport or military base. A TTF is a professionally considered forecast for weather over a two-hour period, and is based on an actual weather report, such as a METAR or SPECI and appended to the end of it. A TTF is similar to or sometimes in addition to a TAF, a terminal aerodrome forecast, but during the TTF's validity period is considered superior to a TAF.

<span class="mw-page-title-main">Stony Rapids Airport</span> Airport in Saskatchewan, Canada

Stony Rapids Airport is located adjacent to Stony Rapids, Saskatchewan, Canada.

A location identifier is a symbolic representation for the name and the location of an airport, navigation aid, or weather station, and is used for staffed air traffic control facilities in air traffic control, telecommunications, computer programming, weather reports, and related services.

Colour states is a system used for quickly showing meteorological conditions.

<span class="mw-page-title-main">Station model</span> Type of meteorological illustration

In meteorology, station models are symbolic illustrations showing the weather occurring at a given reporting station. Meteorologists created the station model to fit a number of weather elements into a small space on weather maps. This allows map users to analyze patterns in atmospheric pressure, temperature, wind speed and direction, cloud cover, precipitation, and other parameters. The most common station plots depict surface weather observations although upper air plots at various mandatory levels are also frequently depicted.

<span class="mw-page-title-main">Meteorological instrumentation</span> Measuring device used in meteorology

Meteorological instruments, including meteorological sensors, are the equipment used to find the state of the atmosphere at a given time. Each science has its own unique sets of laboratory equipment. Meteorology, however, is a science which does not use much laboratory equipment but relies more on on-site observation and remote sensing equipment. In science, an observation, or observable, is an abstract idea that can be measured and for which data can be taken. Rain was one of the first quantities to be measured historically. Two other accurately measured weather-related variables are wind and humidity. Many attempts had been made prior to the 15th century to construct adequate equipment to measure atmospheric variables.

<span class="mw-page-title-main">Automated airport weather station</span> Automated sensor suites

Airport weather stations are automated sensor suites which are designed to serve aviation and meteorological operations, weather forecasting and climatology. Automated airport weather stations have become part of the backbone of weather observing in the United States and Canada and are becoming increasingly more prevalent worldwide due to their efficiency and cost-savings.

<span class="mw-page-title-main">Surface weather observation</span> Fundamental data used for weather forecasts

Surface weather observations are the fundamental data used for safety as well as climatological reasons to forecast weather and issue warnings worldwide. They can be taken manually, by a weather observer, by computer through the use of automated weather stations, or in a hybrid scheme using weather observers to augment the otherwise automated weather station. The ICAO defines the International Standard Atmosphere (ISA), which is the model of the standard variation of pressure, temperature, density, and viscosity with altitude in the Earth's atmosphere, and is used to reduce a station pressure to sea level pressure. Airport observations can be transmitted worldwide through the use of the METAR observing code. Personal weather stations taking automated observations can transmit their data to the United States mesonet through the Citizen Weather Observer Program (CWOP), the UK Met Office through their Weather Observations Website (WOW), or internationally through the Weather Underground Internet site. A thirty-year average of a location's weather observations is traditionally used to determine the station's climate. In the US a network of Cooperative Observers make a daily record of summary weather and sometimes water level information.

A Volcanic Ash Advisory Center (VAAC) is a group of experts responsible for coordinating and disseminating information on atmospheric volcanic ash clouds that may endanger aviation. As at 2019, there are nine Volcanic Ash Advisory Centers located around the world, each one focusing on a particular geographical region. Their analyses are made public in the form of volcanic ash advisories (VAAs), involving expertise analysis of satellite observations, ground and pilot observations and interpretation of ash dispersion models.

<span class="mw-page-title-main">Swiss International Air Lines Flight 850</span> 2002 aviation accident

Swiss International Air Lines Flight 850 was an international scheduled passenger flight from Basel, Switzerland, to Hamburg, Germany. On 10 July 2002, the flight was unable to land at Fuhlsbüttel Airport due to weather. Attempts were made to divert to other airports at Berlin and Eberswalde before the crew decided to land at Werneuchen. On landing, the aircraft struck an earth bank which ripped off all three undercarriage legs, and came to rest on its belly with an engine on fire. One of the sixteen passengers suffered minor injuries. The aircraft was written off.

ICAO Meteorological Information Exchange Model (IWXXM) is a format for reporting weather information in XML/GML. IWXXM includes XML/GML-based representations for products standardized in International Civil Aviation Organization (ICAO) Annex III, such as METAR/SPECI, TAF, SIGMET, AIRMET, Tropical Cyclone Advisory (TCA), Volcanic Ash Advisory (VAA), Space Weather Advisory and World Area Forecast System (WAFS) Significant Weather (SIGWX) Forecast. IWXXM products are used for operational exchanges of meteorological information for use in aviation.

The Weather Information Exchange Model (WXXM) is designed to enable the management and distribution of weather data in digital format (XML). WXXM version 2.0, set to be finalized in 2014, is based on Geography Markup Language (GML) and is one of the GML Application Schemas. It is being developed by the US Federal Aviation Administration (FAA) and the European Organisation for the Safety of Air Navigation (EUROCONTROL). WXXM is a member of a family of data models designed for use in aviation safety, notably Aeronautical Information Exchange Model (AIXM) and the Flight Information Exchange Model (FIXM).

<span class="mw-page-title-main">Present weather sensor</span>

The present weather sensor (PWS) is a component of an automatic weather station that detects the presence of hydrometeors and determines their type and intensity. It works on a principle similar to a bistatic radar, noting the passage of droplets, or flakes, between a transmitter and a sensor. These instruments in automatic weather stations are used to simulate the observation taken by a human observer. They allow rapid reporting of any change in the type and intensity of precipitation, but include interpretation limitations.

References

  1. 1 2 "Chapter 7. Safety of Flight. Section 1. Meteorology". Aeronautical Information Manual . Federal Aviation Administration. Archived from the original on 2009-09-05. Retrieved 2024-12-27.
  2. METAR (MEteorological Terminal Aviation Routine Weather Report) Station Network at the Centre for Environmental Data Archival
  3. Aerodrome Meteorological Observation and Forecast Study Group (AMOFSG) at ICAO.
  4. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 "Chapter 24: Observations". Aviation Weather Handbook (FAA-H-8083-28A ed.). Federal Aviation Administration. 2024.
  5. "Pierce County-Thun Field". National Weather Service. NOAA . Retrieved 27 December 2024.
  6. "782 – Aerodrome reports and forecasts: A user's handbook to the codes". World Meteorological Organization. Retrieved 2009-09-23.
  7. "Aerodrome Weather Report – World Meteorological Organization" (PDF). Archived from the original (PDF) on 2012-02-24.
  8. 1 2 Sky Condition Group NsNsNshshshs or VVhshshs or SKC Department of Atmospheric Sciences at Texas A&M University
  9. 1 2 "MET – 3.0 Appendices". Archived from the original on October 31, 2011.
  10. 1 2 3 4 5 "METAR/TAF List of Abbreviations and Acronyms" (PDF). National Weather Service.
  11. "Air Force Manual 15-111" (PDF). Archived from the original (PDF) on May 27, 2011.
  12. Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C ed.). Federal Aviation Administration. 2023-07-17.
  13. Get Met 2012 Archived 2012-05-18 at the Wayback Machine published by the UK Met Office, p 13
  14. Key to Aerodrome Forecast (TAF) and Aviation Routine Weather Report (METAR)
  15. Key to METAR Surface Weather Observations
  16. "METAR Study Guide". MétéoCentre.com. Retrieved 28 March 2012.
  17. "Aeronautical Information Manual, Section 7-1-7, 'Categorical Outlooks'". Federal Aviation Administration. Archived from the original on 2012-07-26.
  18. "METAR/SPECI Reporting Changes for Snow Pellets (GS) and Hail (GR)" (PDF).
  19. 1 2 10.2 Section II – hourly observations "UTC". See 10.2.10 Column 32 – weather and obstructions to vision.
  20. "Metar Help". College of DuPage.
Decoding
Format specifications
Software libraries
Current reports