How Accurate?

[TrOjAn]

Just had a message from abloke that is into the weather stuff and all that and he stated that on that really wet day, 13th December I think, my records showed 2.6 mm of rain and his was over 30mm.

So, are these Fine Offset stations MILES out or is there a reason?

TrOjAn

[steve]

Where is he? Dave, who is quite close to you, recorded a similar amount to you on Dec 13th:

http://www.laindonweather.co.uk/trends.htm

Steve

[harrym1byt]

Rainfall measured amounts can vary a greatly even when measured from two locations just yards apart. You must have come across situations where you drive down an almost flooded road due to heavy rain, then come to a section where there has been none at all.

I have read where it has been suggested that the FO system's rainfall readings might read a little higher than actual amounts which fell, when compared to a proper manual gauge.

[goldrush]

Just to add to the above.

I have previously set up 2 rain gauges ("real" types not weather station tipping types) in open countryside, some 200 meters apart and they regularly recorded wildly different amounts.
Futher, I can regularly see it raining hard some thousands of meters away, but none here and vice versa.
Like most weather related things, it depends very much upon the local topography.

[dc1500]

The Watson is as accurate as any small tipping rain gauge as far as I can tell. Especially as I have calibrated mine against a standard funnel rain gauge (enhanced by accurately weighing the water rather than estimating the volume). I have calibrated the Watson against this using the excellent Cumulus calibration facility (0.92) and have also compared the two with the standard gauge placed in a correct (best available) siting. The correlation was exceptionally good. As said above, there can be big variations but seeing as it pissed down all day that day then you can tell that guy with 95% confidence you are spot on. !!
Dave.

[dc1500]

WHOOPS! Misread the day! But I got similar to you that day, about 3.8mm or something so all of the above applies except the "pissing down all day" bit !!
Dave

[dionaea]

I have had an Elecsa WS for a couple of years before getting my WH1080.The only difference is that there was no wind direction & no computer USB link. Over that period I had several low or nil readings which were clearly wrong. On opening the rain gauge I have always found some Arthropod to be the problem - spiders making webs over the tipping balance & cases for eggs cause failure & on several occasions earwigs seem to cause non movement. There being a hole in the top & a drain hole in the base means that there will always be access but smearing the sides & base (but not the drain hole) with a layer of Vaseline minimises the problem. You will never stop some of the wind blown spiders from dropping in. If it doesn't seem to be giving proper readings take a look!

Cheers,

Chris