Icao Forecasting Manual
Contents. Naming The (FAA) lays down the definition in its publication the as aviation routine weather report while the international authority for the code form, the WMO, holds the definition to be aerodrome routine meteorological report.
The (part of the ) and the 's both employ the definition used by the FAA. METAR is also known as Meteorological Terminal Aviation Routine Weather Report or Meteorological Aerodrome Report. Origin METARs typically come from or permanent. Reports are generated once an hour or half-hour, but if conditions change significantly, a report known as a special (SPECI) may be issued.
Some METARs are encoded by 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. History The METAR format was introduced 1 January 1968 internationally and has been modified a number of times since. 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 agreement. The 's (WMO) publication No. 782 'Aerodrome Reports and Forecasts' contains the base METAR code as adopted by the WMO member countries.
Information contained in a METAR A typical METAR contains data for the, direction and speed, cover and heights, and. A METAR may also contain information on precipitation amounts, and other information that would be of interest to pilots or meteorologists such as a or PIREP, and (RVR). 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 (TAF). The complement to METARs, reporting forecast weather rather than current weather, are TAFs.
METARs and TAFs are used in broadcasts. Regulation 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 U.S. National differences from the WMO/ICAO model) under the Federal Meteorological Handbook No.
1 (FMH-1), which paved the way for the Manual 15-111 on Surface Weather Observations, being the authoritative document for the U.S. 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.
METAR conventions 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. The two examples which follow illustrate the primary differences between the two METAR variations. Example METAR codes International METAR codes The following is an example METAR from in,. It was taken on 4 February 2005 at 16:00 (UTC). METAR LBBG 041600Z 12012MPS 090V150 1400 R04/P1500N R22/P1500U +SN BKN022 OVC050 M04/M07 Q1020 NOSIG 8849//91=. METAR indicates that the following is a standard hourly observation.
LBBG is the for. 041600Z indicates the time of the observation. It is the day of the month (04) followed by the time of day (1600, which equals 4:00 pm or 6:00 pm local time). 12012MPS indicates the is from 120° at a speed of 12 (23; 27 mph; 44 km/h).
Speed measurements can be in knots (abbreviated KT) or meters per second (abbreviated MPS). 090V150 indicates the wind direction is varying from 90° true (east) to 150° true (south-southeast).
1400 indicates the is 1,400 m (4,600 ft). R04/P1500N indicates the Runway Visual Range (RVR) along 04 is 1,500 m (4,900 ft) and not changing significantly. R22/P1500U indicates RVR along runway 22 is 1,500 m (4,900 ft) and rising. +SN indicates is falling at a heavy intensity. If any precipitation begins with a minus or plus (-/+), it's either light or heavy. BKN022 indicates a broken (over half the sky) cloud layer with its base at 2,200 ft (670 m) (AGL).
The lowest 'BKN' or 'OVC' layer specifies the. OVC050 indicates an unbroken cloud layer (overcast) with its base at 5,000 ft (1,500 m) above ground level (AGL).
M04/M07 indicates the temperature is −4 °C (25 °F) and the dew point is −7 °C (19 °F). An M in front of the number indicates that the temperature/dew point is Celsius. Q1020 indicates the current (in ) is 1,020 (30.12 ).
NOSIG is an example of a forecast which is appended to METARs at stations while a forecaster is on watch. NOSIG means that no significant change is expected to the reported conditions within the next 2 hours.
8849//91 indicates the condition of the runway:. 88 indicates either a specific runway (e.g. 25 = Rwy 25 or 25L; adding 50 will indicate Right Runway) or all the airport's runways ('88').
99 indicates repetition of the last message as no new information received. Some locations will report the runway using 3 characters (e.g. 25L). 4 means the runway is coated with dry snow. 9 means 51% to 100% of the runway is covered. // means the thickness of the coating was either not measurable or not affecting usage of the runway. 91 means the braking index is bad, in other words the tires have bad grip on the runway.
CAVOK is an abbreviation for Ceiling And Visibility OK, indicating no cloud below 5,000 ft (1,500 m) or the highest minimum sector altitude and no or at any level, a visibility of 10 km (6 mi) or more and no significant weather change. = indicates the end of the METAR 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 near, 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=. METAR indicates that the following is a standard hourly observation. KTTN is the ICAO identifier for the. 051853Z indicates the day of the month is the 5th and the time of day is 1853 Zulu/, or 1:53PM.
Icao Manual 7910
04011KT indicates the wind is from 040° true (north east) at 11 knots (20 km/h; 13 mph). In the United States, the wind direction must have a 60° or greater variance for variable wind direction to be reported and the wind speed must be greater than 3 knots (5.6 km/h; 3.5 mph).
1/2SM indicates the prevailing visibility is 1⁄ 2 mi (800 m) SM = statute. VCTS indicates a (TS) in the vicinity (VC), which means from 5–10 mi (8–16 km). SN indicates snow is falling at a moderate intensity; a preceding plus or minus sign (+/-) indicates heavy or light precipitation. Without a +/- sign, moderate precipitation is assumed. FZFG indicates the presence of freezing.
BKN003 OVC010 indicates a broken ( 5⁄ 8 to 7⁄ 8 of the sky covered) cloud layer at 300 ft (91 m) (AGL) and an overcast (8/8 of the sky covered) layer at 1,000 ft (300 m). M02/M02 indicates the temperature is −2 °C (28 °F) and the dew point is −2 °C (28 °F). An M in front of the number indicates a negative Celsius temperature/dew point ('minus'). A3006 indicates the altimeter setting is 30.06 inHg (1,018 hPa). RMK indicates the remarks section follows. Note that what follows are not part of standard observations outside of the United States and can vary significantly.
AO2 indicates that the station is automated with a precipitation discriminator (rain/snow) sensor. Stations that aren't equipped with a rain/snow sensor are designated AO1. TSB40 indicates the thunderstorm began at 40 minutes past the hour at 1840 Zulu/, or 1:40 p.m. SLP176 indicates the current barometric pressure extrapolated to sea level is 1,017.6 hPa (30.05 inHg).
P0002 indicates that 0.02 inches (0.5 mm) of -equivalent precipitation accumulated during the last hour. T10171017 is a breakdown of the temperature and dew point in eight digits separated into two groups of four. The first four digits (1017) indicate the temperature. The first digit (1) designates above or below zero Celsius (0=above zero 1=below zero). The next three digits in the group '017' give the temperature in degrees and tenths of a degree Celsius, −1.7 °C (28.9 °F). The last four digits '1017' indicate the dew point, −1.7 °C (28.9 °F).
Note: ASOS software, as of this update, uses whole degrees in °F to compute the °C values in this group. = indicates the end of the METAR. In Canada, RMK is followed by a description of the cloud layers and opacities, in eighths. For example, CU5 would indicate a cumulus layer with 5⁄ 8 opacity. Cloud reporting is reported by the number of ' (eighths) of the sky that is occupied by cloud. This is reported as: Abbreviation Meaning SKC 'No cloud/Sky clear' used worldwide but in North America is used to indicate a human generated report CLR 'No clouds below 12,000 ft (3,700 m) (U.S.) or 25,000 ft (7,600 m) (Canada)', used mainly within North America and indicates a station that is at least partly automated NSC 'No (nil) significant cloud', i.e., none below 5,000 ft (1,500 m) and no. Not used in North America.
FEW 'Few' = 1–2 oktas SCT 'Scattered' = 3–4 oktas BKN 'Broken' = 5–7 oktas OVC ' = 8 oktas, i.e., full cloud coverage VV Clouds cannot be seen because of fog or heavy precipitation, so vertical visibility is given instead. Flight categories in the U.S. 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 U.S.: Category Visibility Ceiling 5 mi and 3000 ft AGL Marginal VFR Between 3 and 5 mi and/or Between 1,000 and 3,000 ft AGL 1 mi or more but less than 3 mi and/or 500 ft or more but less than 1,000 ft Low IFR. Aeronautical Information Manual. Archived from on 2009-09-05. Retrieved 2007-12-01.
at the Centre for Environmental Data Archival. at ICAO. World Meteorological Organization. Retrieved 2009-09-23. 2011-05-27 at the.
2012-05-18 at the. Published by the UK Met Office, p 13.
Precipitation discriminators are electrically heated at sub-freezing temperatures to calculate the water equivalent of frozen precipitation and snow accumulation. Environment Canada (2012). Retrieved March 28, 2012. 2012-02-24 at the. ^ Department of Atmospheric Sciences at Texas A&M University. ^ 2011-10-31 at the. Archived from on 2012-07-26.
See 10.2.10 Column 32 - weather and obstructions to vision. External links Look up or in Wiktionary, the free dictionary. Decoding. — approved by the National Weather Services Directorate of Environment Canada.
Format specifications. — U.S. Federal Meteorological Handbook No. 1 — Surface Weather Observations and Reports (September 2005). Complete documentation on the METAR format, PDF. — Information on METAR and TAF reports. Also provides a link to current METARs and cycle files.
Software libraries. at the site.
is a application (with a ) that parses METAR reports. and — libraries for METAR fetching and parsing Current reports. Use CTRL+F to search for a station.
Icao Regulations Manual
Input four-letter ICAO identifier to. — Raw and decoded METARs, METAR cycles, trends and graphs for locations worldwide. — An easy method to check current worldwide METAR/TAF weather reports from your browser. Current and historical reports. — searchable by location, can view historical METARs by location. Wind roses based on METAR data.
Icao Documents And Manuals
ICAO's objective in the fields of forecasting, economic planning and analysis is to support commercial air transport developments, in particular planning issues related to airports, airlines and satellite-based air navigation systems and services. This is accomplished through:. of air traffic and other planning parameters at global, regional and route-group levels;. ICAO's strategy for regional traffic forecasting activity meets the demand for specific long-range forecasts in connection with reducing airport and airspace congestion.