Comparing a METAR with the TAF in force

Comparing a METAR with the TAF in force: compare each element with the forecast for that time.

• Visibility: greater or less than forecast.
  • TAF P6SM = greater than 6 SM (TC AIM MET, prevailing visibility).
  • Observed 6 SM or less = less than forecast.
  • Observed 15 SM = as forecast, not greater (sample exam Q76).
• Ceiling: greater or less than forecast.
  • Ceiling = lowest BKN or OVC base, or vertical visibility (VV) in a surface-based obscuration (TC AIM MET ceiling definition).
  • No BKN, OVC or VV on either side: nothing to compare.
  • FEW and SCT are not ceilings.
• Wind speed: greater or less than forecast.

Practice