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Odd rainfall reading

Discussion specific to Davis weather stations
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wxdrew
Posts: 6
Joined: Sun 01 Dec 2019 4:07 pm
Weather Station: Davis Vantage Vue
Operating System: Win10

Odd rainfall reading

Post by wxdrew »

This is odd; this morning Cumulus showed me a rainfall total of 94mm occuring within a 30 minute period, yet the rainfall rate was flat, no spikes. I stopped Cumulus in order to start the Weatherlink software - that and the console agreed on a 0.4mm rainfall occuring at that time. Just in case I pulled the sensor and checked that it was clean, as was the funnel.

I use the Davis Weatherlink IP data logger to read data from the console (at 10Mbps - I didn't think anything ran that slowly these days!). Can anyone explain this anomaly? Normally my readings match quite closely with a VP2 station a couple of miles from here but not this time...

Here's the relevant extract from today's log:
01/12/19,10:10,5.3,90,3.8,1,4,68,0.0,0.0,1022.79,0.0,18.2,56,4,5.3,5.3,0.0,0,0.00,0.00,3.7,126,0.0,67,0.0,0.0
01/12/19,10:20,5.5,90,4.0,1,5,68,0.0,0.2,1022.93,0.2,18.2,56,5,5.5,5.5,0.0,0,0.00,0.00,3.9,136,0.0,67,0.0,0.2
01/12/19,10:50,6.2,89,4.5,1,3,72,0.0,93.8,1022.96,93.8,18.1,56,1,6.2,6.2,0.0,0,0.00,0.00,4.7,160,0.0,77,0.0,93.8
01/12/19,11:00,6.3,89,4.6,2,6,65,0.0,93.8,1022.96,93.8,18.1,57,1,6.3,6.3,0.0,0,0.00,0.00,4.5,166,0.0,65,0.0,93.8

I my maths is anywhere near accurate 94mm is close to 400 tips, that in 30 minutes should have produced an enormous rain-rate spike but as mentioned, the Cumulus graph for that shows a rate of zero for that period.

Davis Vantage Vue (UK spec, 0.2mm tipping spoon)

Any ideas? At the moment I'm kind of discounting mechanical accuracy as the Davis is only a month old. I also had to start with a fresh Cumulus install at the time because my old FO station had misbehaved so much that the entire data set was useless.

User avatar
mcrossley
Posts: 6587
Joined: Thu 07 Jan 2010 9:44 pm
Weather Station: Davis VP2
Operating System: Buster Lite rPi
Location: Wilmslow, Cheshire, UK
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Re: Odd rainfall reading

Post by mcrossley »

Can you zip up your diags folder and attach it - doubt it will show much though.

I see there is a gap in the log when the rain count increased - is this where you stopped Cumulus and ran WL, or did something else happen?

wxdrew
Posts: 6
Joined: Sun 01 Dec 2019 4:07 pm
Weather Station: Davis Vantage Vue
Operating System: Win10

Re: Odd rainfall reading

Post by wxdrew »

Diags attached. To answer your question, I didn't stop Cumulus around the time of the sudden increase, but I would have turned the PC on around 10.30am and let it download the nights readings from the data logger, which is the way I usually run things rather than leave a PC on all the time. I stopped Cumulus a couple of times later that day to double-check my findings with WL.

I've just checked on the console itself that "rain for the last 7 days" is 31.2mm.

Thanks for following-up!
You do not have the required permissions to view the files attached to this post.

User avatar
mcrossley
Posts: 6587
Joined: Thu 07 Jan 2010 9:44 pm
Weather Station: Davis VP2
Operating System: Buster Lite rPi
Location: Wilmslow, Cheshire, UK
Contact:

Re: Odd rainfall reading

Post by mcrossley »

Between Cumulus being shutdown on the 30/11 @23:51 and it being started again on 1/12 @10:39 the rain counter in the station got reset from 93.6 to 0.

The rain counter Cumulus uses is the annual rain total, so was that reset by you?

I'm afraid you will have to manually fix the rainfall totals.

wxdrew
Posts: 6
Joined: Sun 01 Dec 2019 4:07 pm
Weather Station: Davis Vantage Vue
Operating System: Win10

Re: Odd rainfall reading

Post by wxdrew »

Thanks for the diagnosis... no, I didn't reset the rain counter manually - it's a mystery!

thanks again,
Andy

RayProudfoot
Posts: 2787
Joined: Wed 06 May 2009 6:29 pm
Weather Station: Davis VP2 with Daytime FARS
Operating System: Windows XP SP3
Location: Cheadle Hulme, Cheshire, England
Contact:

Re: Odd rainfall reading

Post by RayProudfoot »

Andy,

I leave my netbook on permanently. It helps prevent problems with shutting down and restarting. Also, I reckon people overseas might be interested in my weather in the middle of my night. With the lid closed except for occasional maintenance the power used is minimal. What type of PC are you using?
Cheers,
Ray, Cheshire.

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wxdrew
Posts: 6
Joined: Sun 01 Dec 2019 4:07 pm
Weather Station: Davis Vantage Vue
Operating System: Win10

Re: Odd rainfall reading

Post by wxdrew »

RayProudfoot wrote:
Mon 02 Dec 2019 3:07 pm
Andy,

I leave my netbook on permanently. It helps prevent problems with shutting down and restarting. Also, I reckon people overseas might be interested in my weather in the middle of my night. With the lid closed except for occasional maintenance the power used is minimal. What type of PC are you using?
I do have a netbook - it's an old Acer Atom running XP. I'm sure it's good enough. Something to consider. I built my main PC specifically for photography, so it's not specced for minimal power usage unless I configure it for savage power-saving in which case Cumulus gets hibernated anyway, which is inconvenient. Using the data logger is a compromise, and until I can get this rainfall inconsistency worked out there's no point in me publishing my data (I've just turned off uploads to weather underground for now).

Andy

RayProudfoot
Posts: 2787
Joined: Wed 06 May 2009 6:29 pm
Weather Station: Davis VP2 with Daytime FARS
Operating System: Windows XP SP3
Location: Cheadle Hulme, Cheshire, England
Contact:

Re: Odd rainfall reading

Post by RayProudfoot »

Andy, sounds like you have something very similar to my Samsung NC10 bought in 2009. That is an atom processor running XP. It runs Cumulus and WeatherLink using a useful utility that gives multiple virtual COM ports.

Just copy your entire Cumulus folder over and turn off all power saving bar including when lid is closed. The display turns off automatically and back on when lid opened. Power consumption is minimal.
Cheers,
Ray, Cheshire.

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wxdrew
Posts: 6
Joined: Sun 01 Dec 2019 4:07 pm
Weather Station: Davis Vantage Vue
Operating System: Win10

Re: Odd rainfall reading

Post by wxdrew »

OK, I've managed to correct all the anomalous rainfall readings in Cumulus except for one, and that is the "Last 24 hrs" reading in the Rainfall dialog box on the front screen.
It still insists on displaying a figure of 65.2mm when rainfall over the last 24 hours has actually been 1.4mm.

I'm not sure whether Cumulus is getting this figure from a file somewhere or calculating it from one or more sources. Has anyone got any pointers ? I'm just going round and round on this one ;-)

Thanks to Mark and Ray for help provided so far!

Andy

RayProudfoot
Posts: 2787
Joined: Wed 06 May 2009 6:29 pm
Weather Station: Davis VP2 with Daytime FARS
Operating System: Windows XP SP3
Location: Cheadle Hulme, Cheshire, England
Contact:

Re: Odd rainfall reading

Post by RayProudfoot »

Hi Andy,

Don't worry about Last 24 Hours. It's temporary and won't exist in ... 24 hours. :D
Cheers,
Ray, Cheshire.

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wxdrew
Posts: 6
Joined: Sun 01 Dec 2019 4:07 pm
Weather Station: Davis Vantage Vue
Operating System: Win10

Re: Odd rainfall reading

Post by wxdrew »

RayProudfoot wrote:
Tue 03 Dec 2019 3:47 pm
Hi Andy,

Don't worry about Last 24 Hours. It's temporary and won't exist in ... 24 hours. :D
And that should have occurred to me too :?

Thanks!
Andy

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