Weather Station Rogue Reading?

[Les E]

HI Weatherteers,

Ive had my first ever weather station for almost two weeks now and Im very pleased with it,however today I have a recorded wind gust reading of 25.1mph.Im sure it was not that windy today as I was only working a couple of miles down the road and was raking leaves so I think I would of noticed a wind of that stength.Could it be a rogue reading ,if so how often can they occur.The station was only £60 but seems good enough quality.

Regards Les.

[Cookie]

where is you're station located, is it very exposed?

[Les E]

HI Cookie,

My site is 210 metres but I have my wind meter on top of a home made mast (made from a old extending aluminium tree lopper) at about 12' high,this is to avoid shelter from my hut and a small conifer tree.

Regards Les.

[Terminal Moraine]

Les, how does the exposure of your anemometer site differ from the area where you were raking leaves?

If the anemometer site is more exposed it's quite possible you really did have a gust of 25 mph at 4m above the ground whereas there was nothing noticeable at ground level where you were leaf raking.

Studies have shown that the mean wind speed at 10m above ground level ( the standard height for an anemometer ) is 30% higher than at 2m above the ground. For this reason if you take readings with a hand held anemometer the Met' Office insist that 30% is added to the recorded speed so that it is comparable with other sites where the anemometer is at the standard height.

The only way to be absolutely sure that your anemometer is showing the correct speed is to check it against a calibrated instrument. If it really is showing randomly high readings the reason could be a faulty connection somewhere or the ingress of moisture into the electrics.

How often does the read out update? Presumably on a station costing £60 it will give the average speed over a given number of seconds rather than instantaneous gust speeds. This would imply that the actual maximum gust was actually higher than the 25.1mph you quoted as this would be the average speed over how ever many seconds the read out takes to update.

Edited November 14, 2009 by Terminal Moraine

[Les E]

HI TM,

Thanks for the information,the area I was working was maybe 100metres lower and surrounded by trees and about 4km from my site as the crow flies,so plenty of differances,Ive got a maximum gust rfeading today of 28.2mph which seems about right.The station gives out readings at 48 second intervals its my first serious weather station although it wont be as proffesional as some of you guys are used to ,but it will do me as a first step until I get a more serious one hopefully next year.

Regards Les.

[Terminal Moraine]

HI TM,

Thanks for the information,the area I was working was maybe 100metres lower and surrounded by trees and about 4km from my site as the crow flies,so plenty of differances,Ive got a maximum gust rfeading today of 28.2mph which seems about right.The station gives out readings at 48 second intervals its my first serious weather station although it wont be as proffesional as some of you guys are used to ,but it will do me as a first step until I get a more serious one hopefully next year.

Regards Les.

Yes, Les, that's more than enough difference in location to account for your apparant reading error.

I'd definitely say the anemometer is o.k and it was only your perception that the wind speed was in error due to your sheltered working location.

[Les E]

HI TM,

Thanks for your advice.

Regards Les.