Part 107 weather questions give you reports in their coded form. Once you know the order of the groups, they read quickly.
METAR, group by group
- Type: METAR is the routine hourly report; SPECI is a special report. AUTO means automated; COR means corrected.
- Date and time: six digits, always in UTC. 161753Z is the 16th at 1753 UTC.
- Wind: direction from true north, then speed in knots. 22015G25KT is 220 degrees at 15 knots gusting to 25; 00000KT is calm; VRB is variable.
- Visibility: in statute miles (SM).
- Weather: - light, no sign moderate, + heavy. TS thunderstorm, RA rain, SH showers, FZ freezing, BR mist, FG fog, HZ haze; VC means in the vicinity.
- Sky cover: FEW, SCT (scattered), BKN (broken), OVC (overcast), with heights in hundreds of feet AGL: BKN008 is broken at 800 feet. The ceiling is the lowest broken or overcast layer.
- Temperature and dew point: 18/16 is 18 and 16 degrees Celsius; M means minus.
- Altimeter: A2992 is 29.92 inches of mercury.
TAF forecasts
A TAF covers 24 or 30 hours and is issued four times a day. 0918/1024 means from 1800Z on the 9th to 2400Z on the 10th. In a TAF, P6SM means visibility of more than 6 miles. Change groups:
- FM: a rapid change from that time.
- TEMPO: temporary changes, each lasting less than an hour.
- PROB30: a 30% chance.
- BECMG: a gradual change within the period.
Weather hazards
- Density altitude rises with high elevation, low pressure, high temperature and high humidity, and higher density altitude reduces aircraft performance.
- Thunderstorms pass through towering cumulus, mature and dissipating stages; hazards peak in the mature stage.
- Microbursts are downdrafts usually less than a mile across, up to 6,000 feet per minute, with winds that strengthen for about 5 minutes after reaching the ground.
- Fog: radiation fog forms on clear, calm nights over land; advection fog forms when moist air moves over a colder surface, as on coasts.
The standard atmosphere at sea level is 15 degrees Celsius and 29.92 inches of mercury.