Meteorological services

050-10-04Pablo Asensio Martínez2026-04-013 min

Air Traffic Control Tower for Weather Info

World Area Forecast Centres (WAFC)

WAFCs (World Area Forecast Centres) are meteorological centres designated to prepare and issue significant and upper-air forecasts in digital form on a global basis.

  • Responsibilities: Prepare gridded forecasts of:
    • Upper wind and temperature.
    • Humidity.
    • Geopotential altitude.
    • Tropopause (level and temperature).
    • Maximum wind (direction, speed, and level).
    • Cumulonimbus clouds (CB).
    • Icing and Turbulence.

Tropical Cyclone Advisory (TC Advisory)

Message issued by a TCAC (Tropical Cyclone Advisory Centre) with information on the position, movement, and intensity of a tropical cyclone.

Code Structure:

  1. TC ADVISORY: Message identification.
  2. DTG: Date and time of issue (YYYYMMDD/HHMMZ).
  3. TCAC: Name of the centre (e.g., MIAMI).
  4. TC: Name of the cyclone (e.g., DORIAN).
  5. NR: Advisory number (e.g., 2013/4).
  6. OBS PSN: Observed position of the centre (Lat/Long).
  7. MOV: Direction and speed of movement (e.g., NW 18 KT).
    • SLW (Slow): < 3 kt.
    • STNR (Stationary): < 1 kt.
  8. INTST CHANGE: Intensity change (e.g., INTSF = Intensifying, WKN = Weakening, NC = No Change).
  9. C: Atmospheric pressure at the centre (hPa).
  10. MAX WIND: Maximum surface wind (10 min average).
  11. FCST PSN / MAX WIND: Forecasts at +6, +12, +18, +24 hours.
  12. NXT MSG EXP: Date/time of the next message.

Flight Information Services (ATIS and D-ATIS)

  • ATIS (Automatic Terminal Information Service): Continuous broadcast of routine information for arriving and departing aircraft.
  • D-ATIS (Data Link ATIS): Digital version of ATIS transmitted via data link (ACARS).
    • Advantage: Allows pilots to obtain meteorological and operational information for the destination airport well before being within VHF radio range (e.g., via SATCOM).

Meteorological Phenomena Abbreviations

It is crucial to know the ICAO Annex 3 abbreviations to interpret METAR, TAF, and SIGMET:

  • Precipitation:
    • PL: Ice Pellets.
    • GR: Hail ($\ge$ 5mm).
    • GS: Small Hail / Snow Pellets (< 5mm).
    • SG: Snow Grains.
    • IC: Ice Crystals (not reported as precipitation in METAR, but as obscuration if visibility < 5000m).
  • Other Phenomena:
    • SQ: Squall (Sudden increase in wind of at least 16 kt, reaching 22 kt or more, lasting at least 1 minute).
    • PO: Dust/Sand Whirls.
    • FC: Funnel Cloud (Tornado or Waterspout).
    • SS: Sandstorm.
    • DS: Duststorm.

Runway State Group

In the METAR, information about the state of the runway can be added if there are contaminants (snow, ice, etc.). Format: RDrDr/ErCrereRBrBr (e.g., 88/425035)

  • DrDr: Runway designator (88 = All runways).
  • Er: Type of deposit (4 = Dry snow).
  • Cr: Extent (2 = 11% to 25%).
  • ereR: Depth (50 = 50 mm).
  • BrBr: Friction coefficient / Braking action (35 = 0.35 / Medium-Good).

Aerodrome Warnings and Wind Shear

  • Aerodrome Warnings: Warn of hazardous conditions on the ground (strong wind, frost, etc.).
  • Wind Shear Alerts: Warn of wind shear on approach or take-off.
    • Can be based on aircraft reports (e.g., "Microburst reported by A320 on final approach").

SIGMET

Information issued by a Meteorological Watch Office (MWO) concerning the occurrence or expected occurrence of en-route weather phenomena which may affect the safety of aircraft operations (e.g., Severe Turbulence, Severe Icing, Volcanic Ash, etc.).