Strange rain reading

[Arnie]

Hi to all

This morning my rain gauge registered 8.8mm around 8:15 The temp at the time was approx 2c

There was definitely no rain around the area, in fact as I left for work at 8:05 and the sky was clear

We had frost this morning, could the reading have anything to with the frost?

This is my first winter using the weather station and I wondering if anyone else has experienced anything similar

I do understand that La Crosse units do have some faulty readings, but aren't those readings usually very high ones?

[GraemeT]

Brian,
Do you have any cockatoos or other large birds in your area?

I've had a couple of instances of rain being recorded when I knew it wasn't raining. The most recent was one day last week. When I went outside to investigate, I had a member of the local mob of cockatoos swinging upside down from one of the guy-wires! Pity the camera batteries were flat, else I'd have a photo of him flapping his wings about and sqawking like cockatoos do. He seemed to be enjoying himself... causing fictitious rain readings.

I suppose I should consider myself lucky - he didn't try to eat the anemometer!


Cheers,

[Arnie]

Hi Graeme

We do have plenty of birds around but nowhere close to the rain gauge

Looking back through the data it seems as if I have been having a few days with small dodgy rain readings

[GraemeT]

Is your rain gauge on a pole without guy-ropes? There's always the chance of small (0.5mm) readings if you have a short gust of wind. That is something I also had happening until I added three 2.5mm guy-ropes to stabilise the 5m by 32mm aluminium mast.

The cockies mostly inhabit the trees in the background...


Cheers.

[Arnie]

Graeme
Thats the strange thing about this
My rain gauge is attached to the top rail of my wooden paling fence about 1.8m high
There are no trees within 15m of the gauge

[steve]

If the "rain" wasn't caused by physical movement of the rain gauge bucket, the most likely cause is interference; but I would agree with you that this usually causes huge values. Do you normally run Cumulus all of the time, or start and stop it occasionally? The rainfall total is calculated differently depending on whether it comes from the logger, or whether it is 'live'. There was a bug a long time ago (before I realised how that aspect of the La Crosse works), which could cause slight differences in rainfall when you start and stop Cumulus, but I am pretty sure that is fixed now.

Please zip up and attach your diags folder and I'll see if I can see anything unusual.

[Arnie]

Do you normally run Cumulus all of the time, or start and stop it occasionally?

Cumulus is run 24/7 Steve, however the last couple of days, it has been a bit stop/start because I have been trying to rectify the rain data records(more on another post)

Please zip up and attach your diags folder and I'll see if I can see anything unusual.

Thanks Steve see attached folder

[steve]

It seems that at some point your station's total rain counter went down from 505.5 to 32.63 (reset to zero, perhaps?). Cumulus recognised this and started counting again from zero, using the 32,63 as the rain for the day:

7/4/2010 22:10:45.046 : 10:10:45 PM ****Rain reset? First chance: raindaystart = 505.5, raintotal = 32.6300010681152
7/4/2010 22:10:53.656 : 10:10:53 PM ****Rain counter reset: raindaystart = 505.5, raintotal = 32.6300010681152

It then started using 32.63 as the start of day figure instead of the 505.5:

7/5/2010 06:46:18.343 : Writing todayfile, LastUpdateTime = 7/5/2010 6:45:00 AM raindaystart = 32.6300010681152

On the subsequent start, it correctly reads the 32.63 back:

7/5/2010 06:47:21.562 : Read today file: Date = 7/5/2010, LastUpdateTime = 7/5/2010 6:45:00 AM
7/5/2010 06:47:21.578 : Todayfileraindaystart = 32.6300010681152

and writes that value back again when it closes:

7/5/2010 07:20:51.937 : Writing todayfile, LastUpdateTime = 7/5/2010 7:20:00 AM raindaystart = 32.6300010681152

However, on the next start, the 505.5 is back:

7/5/2010 07:25:27.116 : Read today file: Date = 7/5/2010, LastUpdateTime = 7/5/2010 7:20:00 AM
7/5/2010 07:25:27.116 : Todayfileraindaystart = 505.5

I simply can't account for that. I'm wondering if your today.ini file has got corrupted somehow, could you zip it up and attach it, please?

[Arnie]

Steve
I have started a new post on this exact problem, maybe you could delete that post!!

attached the Today file

[steve]

That looks OK, and 32.63 is the correct value for the start of day if you want zero total for today; so I don't understand how it is getting 505.5. Perhaps you could upload your July log file, and answer my questions from the other thread - i.e. what exactly are you doing to the files when you edit them?

[Arnie]

Steve
The correct reading for 1st July is 505.5 (it was showing as 32.6) we had 0.5mm on the 3rd so the correct reading for Start of today the 5th should now be 506.0mm
All I have done is as the above post,

In the Today file I have changed the 32.6 to 506.0 and saved the file
In the July log I have gone down the page changing the Total rain figure to read the correct 505.5 on 1st to 506.0 on the 3rd and subsequent dates up to the latest time

attached July log

[steve]

That explains it then; Cumulus is getting that figure because you're putting it in there. Your station is saying that its current total counter is 32.6:

05/07/10,20:55,10.9,79,8.4,0.0,0.0,0,0.0,0.0,1023.4,32.6,21.7,64,0.0,11.9,10.9

So 32.6 is the correct figure for the Start= figure in today.ini (assuming zero rain today). Every time you edit it to the incorrect higher figure, Cumulus corrects it and starts counting from zero again, hence the extra rain added each time.

The station total counter is simply an incrementing counter; it's not supposed to represent any particular period of time. The daily amounts are calculated by taking the current value relative to the start of day figure. It's logged in the monthly logs simply as a reference for correcting the figures when the station does something odd with its counter, as yours seems to have done (going down from over 500 to 32.6).

http://wiki.sandaysoft.com/a/FAQ#My_sta ... it_to_zero

[Arnie]

Sorry Steve
The correct figure for Start of Today is 506.0

It was 505.5 on 1st July plus the 0.5mm that fell on the 3rd making Today's Start 506.0

[steve]

You are assuming that the counter actually represents something (your annual total to date or something?); as I said above (and in the FAQ), it does not. It is an arbitrary counter which just keeps incrementing, and can be reset. It would appear that yours has reset (I'd have to see earlier monthly unedited log files to be sure).

Your station says that its counter is currently 32.6 (as logged by Cumulus) and hence the correct figure for the Start= line in today.ini is 32.6.

[Arnie]

All my editing of the Monthly log was a waste

I just could not understand where this 32.6 magical figure appeared from

Thanks Steve