METAR TREND removal and 3 hourly TAF issue
In New Zealand, a trend forecast is appended to each half-hourly METAR-AUTO report for Auckland, Wellington, and Christchurch international aerodromes, and every hourly METAR or SPECI issued for Ohakea and Whenuapai military aerodromes. The trend is written by the MetService Aviation Meteorologist on duty.
After consultation with key users in the NZ aviation industry, we have made the decision to remove the current trend service at Auckland, Wellington, Christchurch, Ohakea and Whenuapai. This will be replaced with a three-hourly update and responsive terminal aerodrome forecast (TAF) at each of these aerodromes (apart from Whenuapai which will continue with the current issue times and validity periods).
These changes will become effective from 7 December 2022.
Why adopt this approach?
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To simplify the system by providing a single accurate forecast.
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By removing trend forecast, it removes the potential of having mismatched forecasts for a single aerodrome.
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This approach is in alignment with other international practises. The USA, Canada, Australia, and Japan have removed trend forecasts in favour of more regularly issued TAFs.
What will this look like?
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All TAFs will continue to be issued within 1 hour before the start of the validity period.
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TAFs will be routinely issued with a validity period starting from 00, 06, 12 and 18 UTC, and will cover a period of 30 hours. In addition to this, there will be a routine update of the TAF, with validity periods starting from 03, 09, 15 and 21 UTC, and will cover a period of 27 hours.
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Alongside these extra routine issues, the forecasts will be kept under continuous review and will be amended if required.
|
TAF Validity Period |
TAF length |
Description |
|
00-06 UTC |
30 hours |
Initial issue |
|
03-06 UTC |
27 hours |
Routine update |
|
06-12 UTC |
30 hours |
Initial issue |
|
09-12 UTC |
27 hours |
Routine update |
|
12-18 UTC |
30 hours |
Initial issue |
|
15-18 UTC |
27 hours |
Routine update |
|
18-00 UTC |
30 hours |
Initial issue |
|
21-00 UTC |
27 hours |
Routine update |