Cumulus Support

In the aftermath of our storm across the south, I looked at my weather site to see what sort of wind speeds were recorded.

However, it is recorded that peak wind speed was 33.6mph during the night, and obviously I expected to see higher than this.

I was looking at the specs for the N96GY, and wind speed measurement is shown as being 0-100mph.

The sensor appears to revolve freely to me, so no issues there.

Anyone else experienced this?

P.S. I have just noticed that with effect from the beginning of September, air pressure is just "flat-lining" at 1013 or thereabouts-does this sensor fail? I have reset station and base unit, but to no avail.

Thanks,

Rob.

Hi Rob,

That's almost exactly the same as recorded by my station (it has recorded somewhat higher windspeeds previously). I've just looked at the websites of three Cumulus stations in the Southampton area and they all (to my surprise) reported maxima in the lower 30 mph region for "today". Of course before drawing any definite conclusions, it would be necessary to do some more "research", to check the manufacturer of their stations (a great many are Maplin/FO's) and how well set-up and maintained they are. Bear in mind that the "official" measurement of windspeed is at the top of a 10 metre pole in an unobstructed environment (typically an airfield). How high above any obstructions is your Maplin anemometer?

The classic "three cup anemometer" is generally considered to be "linear" (rpm versus windspeed) and my FO console does appear to report high rpm (pulses generated artificially) correctly up to 90 mph (and a synthesised "gust" up to almost 200 mph ! ).

Personally, I haven't been able to "prove" any major errors in the calibration of the FO anemeometer up to about 30 mph. But Steve (who experiences high wind speeds far more often than the rest of us) has said that he thinks the FO "gust" value may be a better indicator of average windspeed.

Re your PS: Any sensor can fail (FO's probably more than most) and I believe somebody else reported a "frozen" FO barometer on the forum recently. But it's not one of the "well known" issues with the Maplin/FO stations.

Cheers, Alan.

I wouldn't necessarily think there is something wrong with the equipment on this occasion. Even looking at the Met Office's own stations shows some remarkable variations. St Catherine's Point (IOW) shows general wind speeds of 30 - 40 mph, and few periods of gusts above 50 mph. Yet we are told that at the Needles there was a gust of 99 mph. WOW web site shows some areas in the middle of the 'track' which never seemed to get above 30 - 40mph.

The Maplin anemometer seems to be capable of reasonable accuracy at least up to 50mph comparing it with professional stations in my area. What it does beyond that I can't say. It is very important to regularly maintain it, and check it moves freely.

Thank you both for taking the time to reply, and it has given me some food for thought.

I thought I had eliminated everything bar a fault with the weather station, but it has got me thinking that localised conditions may very well have been different to those on the forecast, plus of course the actual placement of my weather station - I must admit it is very much at ground level, and therefore not ideally placed with regards to proximity to the house.

Thank you both once again for your helpful replies.

Regards,

Robert.

Hi Robert,
I am not too far from your location and recorded a gust of 53.9 mph at 05:19 yesterday. My station is a FO WH1090 and the anemometer is mounted above the roof line of the house - about 8 metres above ground level.
The anemometer bearing failed in January this year after less than 6 months use.
FYI, I replaced the original with a sealed one http://www.bearingshopuk.co.uk/mr105-2rs-20699-p.asp

Regards .......... Peter

Thanks Peter,

I followed the link you posted and have ordered that bearing.

I did pop the sensor apart previously in order to apply a little light oil, so I will prise it apart again and fit that bearing.

Out of curiosity, I do have a pergola at the bottom of the garden, with some quite sturdy uprights - how did you go about securing your weather station? I didn't know whether to find a slightly larger outer pole and try and affix to the square upright legs of my pergola and just drop it into place, but I was wondering how you overcome any tendancy for it to rotate within its mount and give false wind direction indication?

Thanks again,

Robert.

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My FO recorded a max of 46.3mph during the storm.

About 4 miles away and about 1.5miles closer to the coast 76mph was recorded with a David Pro.
My setup is lower, and does have more obstacles, called houses surround it, so it may have been more sheltered