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W-8681 Wind Gust
Posted: Sat 14 Nov 2009 11:19 am
by timsoles
I'm a bit confused on the Wind Gust.
Yesterday evening I observed a gust of 26.6 mph and this is still showing as the maximum wind speed record on the station.
Looking at the Cumulus data, this figure has not been transferred, and I am showing an all time high of 15.9 mph from August. Looking at the log file, the second column is showing figures of 14.2 to 15.3 during the period in question.
On the station settings in Cumulus, 'Calculate 10 min wind average' is NOT ticked.
Any suggestions as to why my maximum gust is not showing in the Cumulus data?
Thanks
Tim
Re: W-8681 Wind Gust
Posted: Sat 14 Nov 2009 12:21 pm
by steve
In Cumulus 1, the log is just a snapshot of the values at the time of the log entry, so recent highs and lows don't necessarily appear in there.
I don't know why that gust didn't become your all-time high, though, the code that does that is pretty simple, mature and reliable. Was Cumulus actually running at the time of the high gust?
It does seem like a suspiciously high value, incidentally, nearly double the other speeds at that time.
Re: W-8681 Wind Gust
Posted: Sat 14 Nov 2009 12:50 pm
by timsoles
Steve, Bear with me - I'm a bit of a novice on this. Also, it is unusually windy down south at the moment which is why we have been watching the station!
When I refer to log, I am looking at the Nov09log.txt and the file is being updated every 30 minutes.
Cumulus was not running at the time of the high gust. We tend to plug the station into the PC once a day to update Cumulus, but otherwise keep the station elsewhere in the house where it's more readily viewable.
I tap the wind speed on the station 5 times to view maximum record of 26.6 mph but no sign of this in Cumulus. Is there anything else I can check?
Cheers, Tim
Re: W-8681 Wind Gust
Posted: Sat 14 Nov 2009 1:30 pm
by steve
When Cumulus is using data from the logger that was recorded while it wasn't running, it will only see data that was saved to the logger. The longer the station logging interval, the more likely it is that station won't have logged the peak gusts, and therefore Cumulus will never see them.
Cumulus generates its own all-time records from the data that it reads; it doesn't use the all-time records in the station. It's possible that at some point I will add a facility to download them from the station to replace the Cumulus-generated records.
Re: W-8681 Wind Gust
Posted: Sat 14 Nov 2009 2:00 pm
by timsoles
I hadn't realised that.
So is there any downside to changing the data logger frequency to 1 minute for more accurate data recordings?
Re: W-8681 Wind Gust
Posted: Sat 14 Nov 2009 2:13 pm
by steve
timsoles wrote:I hadn't realised that.
So is there any downside to changing the data logger frequency to 1 minute for more accurate data recordings?
I think the minimum you can set the station logger to is 5 minutes. You can set Cumulus to 1 minute, but it can only log at the same interval as the station when it's using logger data.
The only disadvantages I can think of are that the logger fills up more quickly (but even at 5 minutes you still get about two weeks worth), and you use up more disc space with Cumulus logs. My monthly logs are about 700kb each at a 5-minute logging interval. I wouldn't have thought that was much of an issue for most people.
Re: W-8681 Wind Gust
Posted: Sat 14 Nov 2009 2:28 pm
by timsoles
I have set the station log to 1 minute and just recorded a record high gust of 22.1 mph in Cumulus.
Looking at the log, the data is different every minute.
I've got masses of disk space, so file size is not an issue.
Thanks Steve - I'm now recording what I wanted to see.
Nice to have some stormy weather in the home counties - it's normally quite boring down here!