PKPF68-77

I believe that the half-hourly METARS use
wind direction
mean speed
gust speed

"taken for a period of several minutes just prior to the time of the observation".

Clearly, if you take this literally, this means that the highest gust speed since the last METAR (on a day of no "specials") may not be included.
However, some, or all of you may prefer to use the highest gust of the previous half hour? Be glad to hear your views.

I am asking this only to show that in a list of METARS I have for part of a day, the highest gust of the period may not be included.

Cheers, guys.

PS - Query is nothing whatsoever to do with an aviation matter - merely a minor land-based incident.

cleo

I'm no longer current so stand to be corrected but I believe that gusts in the 10 minutes preceding the observation are included. Bear in mind that a full 'manual' observation ie no automatic readings can take up to 15 minutes to carry out and code up so yes its possible that the highest gust of the day might not be included in the METAR but ought to be recorded as a comment in the register.

matspart3

Most automated kit has a 2-minute or 10-minute 'average' setting, which will record the highest in that period, so your assumption that the highest gust could (and, technically, should) be ommitted from the METAR is correct.

PKPF68-77

Thanks for that, cleo and matspart3.

Looks like I will also have to purchase data from nearest anemometer site to Glasgow. (Bishopton if anyone is interested.)


Off at a tangent, now, we don't really know what the max gust at Hamburg was on the day of the hairy landing in Xwinds then? At least not from the list of METARS if same system is used in Europe.

Dizzee Rascal

As cleo said, the wind in a METAR is the 10 minute average preceeding the observation.

PKPF68-77

Thank you for that, diz.

datafox

Off at a tangent, now, we don't really know what the max gust at Hamburg was on the day of the hairy landing in Xwinds then? At least not from the list of METARS if same system is used in Europe.

I don't have the METAR anymore, but I believe the max wind gust reported in the METARs was 49 knots near the time of the incident? Most likely the weather observing equipment records the peak wind speed and the time it occurred, but no, in European METARs the peak speak isn't reported unless it occurs in the 10 minutes preceding the observation.

Spitoon

Continuing the tangent - the peak speak isn't reported unless it occurs in the 10 minutes preceding the observation and it is 10kts or more greater than the mean speed.

So, let us imagin that the METAR includes the wind group 27035G49 - it is quite possible that a substantially stronger gust, say 55kts, occurred 15 minutes before the time of the observation but it would not be mentioned in the METAR. (I don't know about other parts of the world but in the UK the days of entering such data in a register are long past.)

Of course, such a gust would almost certainly be reported by RTF to the pilot of an aircraft taking off or landing, but only if it occurred during the 2 minutes before the controller transmitted the message. Those are the rules anyway - many controllers that I know would augment the required wind reports with additional information in such conditions.

M609

I use common sense when reading wind to aircraft. Sure, the 2 min wind at the thr is what I primarily use, but if it's a freak calm in prevailing winds I give crews a heads up as well. Likewise if the wind is calm at the airfield, but G30 at a hilltop 1 nm at 1100ft, I tell them that as well. No mention about that in the book, it just seems pertinent to do so.