Meteorology for Air Traffic Services
What the controller must read
Controllers use METAR (routine), SPECI (special), TAF (forecast), SIGMET (significant en-route weather), AIRMET (moderate hazards), and warnings such as wind shear and volcanic ash advisories. Know the decoding: wind direction/speed/gusts, visibility, RVR, present weather, cloud amount and height, temperature/dewpoint, QNH, and trend. Traps: confusing QNH with QFE and QNE (standard 1013.25 hPa), misreading RVR trends, and forgetting that a SPECI is issued when conditions cross specified criteria.
Operational effects
Low visibility triggers LVP and reduced runway separation; thunderstorms bring microbursts, hail, icing and turbulence; icing affects performance; wake turbulence is affected by wind. A question may ask which phenomenon requires a SIGMET - answer includes severe turbulence, severe icing, volcanic ash, tropical cyclone, and low-level wind shear.
Rule of thumb
QNH = altitude above mean sea level; QFE = height above aerodrome; QNE = standard pressure for flight levels. If the question mentions "flight level", think 1013.25 hPa.
Worked example
METAR shows "25012G25KT 4000 TSRA BKN008". Read: wind 250° at 12 kt gusting 25, visibility 4 km, thunderstorm with rain, broken cloud at 800 ft. Expect low-level wind shear and possible microburst; consider LVP.