Terminal Aerodrome Forecasts (TAFS) — Page 492, Lesson 464

I want to walk you through Terminal Aerodrome Forecasts, or TAFs. These are forecasts of meteorological conditions at an aerodrome, as opposed to a METAR, which reports actual, present conditions. The format of a TAF is similar to a METAR, with many of the coding groups identical in both. TAFs usually cover a period of between 9 and 30 hours. 9-hour TAFs are issued every 3 hours, and 12 to 24-hour TAFs are issued every 6 hours. Let's look at some examples of 9-hour TAFs. For Kirkwall: TAF EGPA 160602Z 1607/1616 15010 9999 SCT012 BKN030 PROB320 TEMPO 1607/1613 7000 -RADZ SCT008 BKN012=. For Aberdeen: TAF EGPD 160656Z 1607/1616 13008KT 4000HZ TEMPO 1609/1612 5000 HZ BKN007=. For Inverness: TAF EGPE 160656Z 1607/1616 VRB03KT 9999 FEW035=. For Santiago: TAF LEST 160800Z 1610/1619 24007KT 9999 SCT040=. For Valencia: TAF LEVC 160800Z 1610/1619 12008KT CAVOK TEMPO 1614/1619 05006KT=. Now, let's decode a TAF. The first code that appears is the identifier, TAF. The next code is the ICAO location indicator of the aerodrome for which the report is issued. In the example TAF EGTK 130600Z 1307/1316 31015KT 8000 -SHRA SCT010 BKN018=, EGTK is the ICAO location indicator for Oxford, Kidlington airport. The date-time information in TAFs is slightly different from that in a METAR because a TAF gives a forecast for a period of time. There are two items of date-time information. The first date-time group indicates the date and time at which the TAF was issued. In the example, 130600Z: the digits 13 identify the day of the month, followed by the time in hours and minutes UTC. So this TAF was issued on the 13th of the month at 0600 hours UTC. In a TAF, Coordinated Universal Time, UTC, is indicated by the letter Z. The next code-group identifies the period of validity of the TAF. This uses an eight-digit format. The first four digits show the start date and time, so 1307 indicates that the TAF's validity period starts on the 13th at 0700Z. The next four digits are the end date and time.