KDFW Dallas-Fort Worth

PANC Anchorage, Alaska

PHNL Honolulu, Hawaii

The date/time of the forecast origin group (YYGGggZ) follows the terminal’s location identifier. It contains the day of the month in two digits (YY) and the time in four digits (GGgg in hours and minutes) in which the forecast is completed and ready for transmission, with a Z appended to denote UTC. This time is entered by the forecaster. A routine forecast, TAF, is issued 20 to 40 minutes before the beginning of its valid period.

Examples:

The TAF was issued on the sixth day of the month at 1737 UTC.

The TAF was issued on the 12th day of the month at 1123 UTC.

The TAF valid period (Y Y G G /Y Y G G ) follows the date/time of the forecast origin group. Scheduled 24- and 30-hour TAFs are issued four times per day, at 0000, 0600, 1200, and 1800Z. The first two digits (Y Y ) are the day of the month for the start of the TAF. The next two digits (G G ) are the starting hour (UTC). Y Y is the day of the month for the end of the TAF, and the last two digits (G G ) are the ending hour (UTC) of the valid period. A forecast period that begins at midnight UTC is annotated as 00. If the end time of a valid period is at midnight UTC, it is annotated as 24. For example, a 00Z TAF issued on the 9th of the month and valid for 24 hours would have a valid period of 0900/0924.

Whenever an amended TAF (TAF AMD) is issued, it supersedes and cancels the previous TAF. That is, users should not wait until the start of the valid period indicated within the TAF AMD to begin using it.

Examples

The TAF is valid from the 15th day of the month at 1200 UTC until the 16th day of the month at 1200 UTC.

This is a 30-hour TAF valid from the 23rd day of the month at 0600 UTC until the 24th day of the month at 1200 UTC.

This is an amended TAF valid from the 1st day of the month at 2100 UTC until the second day of the month at 1800 UTC.