Reporting Of Gusts In Tafs
Thread Starter
Joined: Feb 2003
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From: UK
Reporting Of Gusts In Tafs
Assume that the w/v in a TAF is reported as 31029G39. I have always assumed that this means the mean windspeed is 29 kts with maximum gusts of 39 kts. I know that gusts do not need to be reported unless they are >10 kts more than the mean, but now have been told that there is a 10 kt tolerance on reporting of gusts: this means that on a report of gusts of 39 kts, there is a possibility that gusts may reach 49 kts. Anyone care to comment?
Joined: Nov 2000
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From: Scandiland
My qualified guess is that because of the fact that gusts are very hard to predict, there is such tolerance to keep the meteorologists back free...
When gusts are reported, one should allways keep in mind that it may get much worse than forcast. And this is also explains further why one should "interpret" the TAF and not just read it and use it s the plain truth.
nother exmple is the T/Td. If they are the sme value, but no fog is forcast, that should ring a bell.
/LnS
When gusts are reported, one should allways keep in mind that it may get much worse than forcast. And this is also explains further why one should "interpret" the TAF and not just read it and use it s the plain truth.
nother exmple is the T/Td. If they are the sme value, but no fog is forcast, that should ring a bell.
/LnS
Joined: Nov 2004
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From: Sunny East Sussex
No, the gust value is the max gust expected.
The reason you see a 10kt gust factor a lot of the time, is due to the expected gust being 8 kts, so it is rounded up to the min reportable gust of 10.
Also, when using these gusts to predict crosswinds, remember that TAF/METAR winds are in True, whereas ATIS/ATC winds are Mag. My chief MetO used to say "The met man always tells the truth"
The reason you see a 10kt gust factor a lot of the time, is due to the expected gust being 8 kts, so it is rounded up to the min reportable gust of 10.
Also, when using these gusts to predict crosswinds, remember that TAF/METAR winds are in True, whereas ATIS/ATC winds are Mag. My chief MetO used to say "The met man always tells the truth"
Joined: Aug 2000
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From: UK
Assume that the w/v in a TAF is reported as 31029G39. I have always assumed that this means the mean windspeed is 29 kts with maximum gusts of 39 kts. I know that gusts do not need to be reported unless they are >10 kts more than the mean, but now have been told that there is a 10 kt tolerance on reporting of gusts: this means that on a report of gusts of 39 kts, there is a possibility that gusts may reach 49 kts. Anyone care to comment?
In a METAR, Gxx menas that xx is the maximum windspeed detected in the 10 mins prior to the observation.
In a TAF, Gxx means that xx is the maximum windspeed forecast.
There's no "10 kt tolerance".
Thread Starter
Joined: Feb 2003
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From: UK
Re above
To close the thread, I e-mailed the Met Office for their advice. Their reply was,
'Thank you for you email.
There is a band of values that the forecasters use, for example 40kts as the gust is the mean gust speed this could be up to 49kts then after that it would appear as 50kts.
Hope this helps'
'Thank you for you email.
There is a band of values that the forecasters use, for example 40kts as the gust is the mean gust speed this could be up to 49kts then after that it would appear as 50kts.
Hope this helps'
Joined: Aug 2000
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From: UK
Then could you let me know by PM who at the Met Office told you that please? While the response is very unclear, it does seem to be saying something that is at odds with the instructions in WMO Doc 306 Manual on Codes.
