Decoding METARs and TAFs

A METAR is an observation of current surface weather at an airport, always in the same order: station identifier, day and time in Zulu, wind as direction and speed, visibility in statute miles, present weather, sky condition with cloud bases, temperature and dewpoint in Celsius separated by a slash, and the altimeter setting after the letter A. So "24016G24KT 10SM FEW070 24/18 A2992" reads as wind from 240 at 16 gusting 24 knots, ten miles visibility, few clouds at 7,000 feet, temperature 24 and dewpoint 18 Celsius, altimeter 29.92. A TAF looks similar but is a forecast for the area within about five statute miles of the airport, usually valid 24 to 30 hours, and it adds change groups: FM marks a rapid lasting change from a stated time, BECMG marks a gradual change, and TEMPO marks brief temporary fluctuations under an hour. Work the timing math the test asks for: a valid period "0912/1012" runs from the 9th at 1200Z to the 10th at 1200Z; "FM100300" switches the forecast at the 10th, 0300Z; and a TEMPO group applies only within its stated window. Remember the ceiling definition — the lowest BROKEN or OVERCAST layer (or vertical visibility into an obscuration) — because choosing VFR versus IFR from a report turns on it. Precipitation and obscuration codes follow a small vocabulary: RA rain, SN snow, TS thunderstorm, FG fog (visibility below 5/8 mile), BR mist, HZ haze, with intensity marked by a minus or plus sign, so "-RA BR" is light rain and mist. The essential distinction is simple — a METAR reports what is observed now, and a TAF forecasts what is expected later. Practice on real coded reports until the decode is automatic; the exam presents them cold.